Traditional Medicines in Africa: An Appraisal of Ten
Potent African Medicinal Plants
M. Fawzi Mahomoodally
Department of Health Sciences, Faculty of Science,
University of Mauritius, 230 Réduit, Mauritius
Received 23 May 2013; Revised 27 September 2013; Accepted
10 October 2013
Academic Editor: John R. S. Tabuti
Copyright © 2013 M. Fawzi Mahomoodally. This is an open
access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
Abstract
The use of medicinal plants as a fundamental component of
the African traditional healthcare system is perhaps the oldest and the most
assorted of all therapeutic systems. In many parts of rural Africa, traditional
healers prescribing medicinal plants are the most easily accessible and
affordable health resource available to the local community and at times the only
therapy that subsists. Nonetheless, there is still a paucity of updated
comprehensive compilation of promising medicinal plants from the African
continent. The major focus of the present review is to provide an updated
overview of 10 promising medicinal plants from the African biodiversity which
have short- as well as long-term potential to be developed as future
phytopharmaceuticals to treat and/or manage panoply of infectious and chronic
conditions. In this endeavour, key scientific databases have been probed to
investigate trends in the rapidly increasing number of scientific publications
on African traditional medicinal plants. Within the framework of enhancing the
significance of traditional African medicinal plants, aspects such as
traditional use, phytochemical profile, in vitro, in vivo, and
clinical studies and also future challenges pertaining to the use of these
plants have been explored.
1. Introduction
Traditional medicine is the sum total of knowledge,
skills, and practices based on the theories, beliefs, and experiences
indigenous to different cultures that are used to maintain health, as well as
to prevent, diagnose, improve, or treat physical and mental illnesses [1].
Traditional medicine that has been adopted by other populations (outside its
indigenous culture) is often termed complementary or alternative medicine (CAM)
[1,2].
The World Health Organization (WHO) reported that 80% of
the emerging world’s population relies on traditional medicine for therapy.
During the past decades, the developed world has also witnessed an ascending
trend in the utilization of CAM, particularly herbal remedies [3]. Herbal
medicines include herbs, herbal materials, herbal preparations, and finished
herbal products that contain parts of plants or other plant materials as active
ingredients. While 90% of the population in Ethiopia use herbal remedies for
their primary healthcare, surveys carried out in developed countries like
Germany and Canada tend to show that at least 70% of their population have
tried CAM at least once [2, 3]. It is likely that the profound knowledge
of herbal remedies in traditional cultures, developed through trial and error
over many centuries, along with the most important cures was carefully passed
on verbally from one generation to another. Indeed, modern allopathic medicine
has its roots in this ancient medicine, and it is likely that many important
new remedies will be developed and commercialized in the future from the
African biodiversity, as it has been till now, by following the leads provided
by traditional knowledge and experiences [2–5].
The extensive use of traditional medicine in Africa,
composed mainly of medicinal plants, has been argued to be linked to cultural
and economic reasons. This is why the WHO encourages African member states to
promote and integrate traditional medical practices in their health system [1].
Plants typically contain mixtures of different phytochemicals, also known as
secondary metabolites that may act individually, additively, or in synergy to
improve health. Indeed, medicinal plants, unlike pharmacological drugs,
commonly have several chemicals working together catalytically and
synergistically to produce a combined effect that surpasses the total activity
of the individual constituents. The combined actions of these substances tend
to increase the activity of the main medicinal constituent by speeding up or
slowing down its assimilation in the body. Secondary metabolites from plant’s
origins might increase the stability of the active compound(s) or phytochemicals,
minimize the rate of undesired adverse side effects, and have an additive,
potentiating, or antagonistic effect. It has been postulated that the enormous
diversity of chemical structures found in these plants is not waste products,
but specialized secondary metabolites involved in the relationship of the
organism with the environment, for example, attractants of pollinators, signal
products, defensive substances against predators and parasites, or in
resistance against pests and diseases. A single plant may, for example, contain
bitter substances that stimulate digestion and possess anti-inflammatory
compounds that reduce swellings and pain, phenolic compounds that can act as an
antioxidant and venotonics, antibacterial and antifungal tannins that act as
natural antibiotics, diuretic substances that enhance the elimination of waste
products and toxins, and alkaloids that enhance mood and give a sense of
well-being [1–5]. Although some may view the isolation of phytochemicals and
their use as single chemical entities as a better alternative and which have
resulted in the replacement of plant extracts’ use, nowadays, a view that there
may be some advantages of the medical use of crude and/or standardized extracts
as opposed to isolated single compound is gaining much momentum in the
scientific community.
2. African Traditional Medicine
African traditional medicine is the oldest, and perhaps
the most assorted, of all therapeutic systems. Africa is considered to be the
cradle of mankind with a rich biological and cultural diversity marked by
regional differences in healing practices [2, 6]. African traditional
medicine in its varied forms is holistic involving both the body and the mind.
The traditional healer typically diagnoses and treats the psychological basis
of an illness before prescribing medicines, particularly medicinal plants to
treat the symptoms [2, 6–8]. The sustained interest in traditional
medicine in the African healthcare system can be justified by two major
reasons. The first one is inadequate access to allopathic medicines and western
forms of treatments, whereby the majority of people in Africa cannot afford
access to modern medical care either because it is too costly or because there
are no medical service providers. Second, there is a lack of effective modern
medical treatment for some ailments such as malaria and/or HIV/AIDS, which,
although global in distribution, disproportionately affect Africa more than
other areas in the world.
The most common traditional medicine in common practice
across the African continent is the use of medicinal plants. In many parts of
Africa, medicinal plants are the most easily accessible health resource
available to the community. In addition, they are most often the preferred
option for the patients. For most of these people, traditional healers offer
information, counseling, and treatment to patients and their families in a
personal manner as well as having an understanding of their patient’s
environment [2, 6, 7]. Indeed, Africa is blessed with enormous
biodiversity resources and it is estimated to contain between 40 and 45,000
species of plant with a potential for development and out of which 5,000
species are used medicinally. This is not surprising since Africa is located
within the tropical and subtropical climate and it is a known fact that plants
accumulate important secondary metabolites through evolution as a natural means
of surviving in a hostile environment [9]. Because of her tropical conditions,
Africa has an unfair share of strong ultraviolet rays of the tropical sunlight
and numerous pathogenic microbes, including several species of bacteria, fungi,
and viruses, suggesting that African plants could accumulate chemopreventive
substances more than plants from the northern hemisphere. Interestingly, Abegaz
et al. [10] have observed that of all species of Dorstenia (Moraceae)
analysed, only the African species, Dorstenia mannii Hook.f, a
perennial herb growing in the tropical rain forest of Central Africa contained
more biological activity than related species [9–11].
Nonetheless, the documentation of medicinal uses of
African plants and traditional systems is becoming a pressing need because of
the rapid loss of the natural habitats of some of these plants due to
anthropogenic activities and also due to an erosion of valuable traditional
knowledge. It has been reported that Africa has some 216 million hectares of
forest, but the African continent is also notorious to have one of the highest
rates of deforestation in the world, with a calculated loss through
deforestation of 1% per annum [7, 12]. Interestingly, the continent also
has the highest rate of endemism, with the Republic of Madagascar topping the
list by 82%, and it is worth to emphasize that Africa already contributes
nearly 25% of the world trade in biodiversity. Nonetheless, the paradox is that
in spite of this huge potential and diversity, the African continent has only
few drugs commercialized globally [2, 12, 13].
The scientific literature has witnessed a growing number
of publications geared towards evaluating the efficacy of medicinal plants from
Africa which are believed to have an important contribution in the maintenance
of health and in the introduction of new treatments. Nonetheless, there is
still a dearth of updated comprehensive compilation of promising medicinal
plants from the African continent.
The main aim of the present review is to highlight the
importance and potential of medicinal plants from the African biodiversity
which have short- as well as long-term potential to be developed as future
phytopharmaceuticals to treat and/or manage panoply of infectious and chronic
conditions. The review might also provide a starting point for future studies
aimed at isolation, purification, and characterization of bioactive compounds
present in these plants as well as exploring the potential niche market of
these plants. In this endeavor, major scientific databases such as EBSCOhost,
PubMed Central, Scopus (Elsevier), and Emerald amongst others have been probed
to investigate trends in the rapidly increasing number of scientific
publications on African traditional medicinal plants. Ten medicinal plants
(Acacia senegal, Aloe ferox, Artemisia herba-alba, Aspalathus
linearis, Centella asiatica, Catharanthus roseus, Cyclopia
genistoides, Harpagophytum procumbens, Momordica charantia,
and Pelargonium sidoides) of special interest were chosen for more
detailed reviews based on the following criteria: medicinal plants that form
part of African herbal pharmacopeia with commercial importance and those plants
from which modern phytopharmaceuticals have been derived.
2.1. Acacia senegal (L.) Willd. (Leguminosae:
Mimosoideae)—Gum Arabic
Acacia senegal, also known as gum Arabic, is native to
semidesert and drier regions of sub-Saharan Africa, but widespread from
Southern to Northern Africa. It is used as a medicinal plant in parts of
Northern Nigeria, West Africa, North Africa, and other parts of the world [8].
The use of gum arabic (or gum acacia), which is derived from an exudate from
the bark, dates from the first Egyptian Dynasty (3400 B.C.). It was used in the
production of ink, which was made from a mixture of carbon, gum, and water.
Inscriptions from the 18th Dynasty refer to this gum as “komi” or “komme.” Gum
arabic has been used for at least 4,000 years by local people for the
preparation of food, in human and veterinary medicine, in crafts, and as a
cosmetic. The gum ofA. senegal has been used medicinally for centuries,
and various parts of the plant are used to treat infections such as bleeding,
bronchitis, diarrhea, gonorrhea, leprosy, typhoid fever, and upper respiratory
tract infections. African herbalists use gum acacia to bind pills and to
stabilize emulsions. It is also used in aromatherapy for applying essential
oils [8, 14–16].
Currently, A. senegal is an important naturally
occurring oil-in-water emulsifier, which is in regular use in the food and
pharmaceutical industries. Medicinally, gum arabic is used extensively in
pharmaceutical preparations and is a food additive approved as toxicologically
safe by the Codex Alimentarius. It has been used as demulcent, skin protective
agent, and pharmaceutical aids such as emulsifier and stabilizer of suspensions
and additives for solid formulations. It is sometimes used to treat bacterial and
fungal infections of the skin and mouth. It has been reported to soothe the
mucous membranes of the intestines and to treat inflamed skin [17,18]. The
demulcent, emollient gum is used internally against inflammation of intestinal
mucosa and externally to cover inflamed surfaces, as burns, sore nipples, and
nodular leprosy. Additionally, it has also been documented to be used as
antitussive, expectorant, astringent, catarrh and against colds, coughs,
diarrhea, dysentery, gonorrhea, hemorrhage, sore throat, typhoid, and for
urinary tract ailments [18]. The gum of A. senegal has been
pharmaceutically used mainly in the manufacture of emulsions and in making
pills and troches (as an excipient), as demulcent for inflammations of the
throat or stomach and as masking agent for acrid tasting substances such as
capsicum and also as a film-forming agent in peel-off masks. Gum arabic is also
used widely as an ingredient in foods like candies and soft drinks as the gum
has the properties of glue that is safe to eat. Gum acacia is widely used in
organic products as natural alternative to chemical binders and is used in
commercial emulsification for the production of beverages and flavor
concentrates [8, 17–19].
Recently, it has been reported that A.
senegal bark extracts were evaluated in vitro for their
antimicrobial potential against human pathogenic isolates (Escherichia
coli, Staphylococcus aureus, Streptococcus pneumoniae,Klebsiella
pneumoniae, Shigella dysenteriae, Salmonella
typhi, Streptococcus pyogenes, Pseudomonas aeruginosa,
and Proteus vulgaris). The extract was found to exhibit significant
antibacterial activity which was suggested to be due to the presence of tannins
and saponins in the plant. It was also reported that the plant extract may not
be toxic to man following in vitro cytotoxicity evaluation [18].
2.2. Aloe ferox Mill. (Xanthorrhoeaceae)—Bitter
Aloe or Cape Aloe
Aloe ferox is native to South Africa and Lesotho and
is considered to be the most common Aloe species in South Africa. A.
ferox has been used since time immemorial and has a well-documented
history of use as an alternative medicine and is one of the few plants depicted
in San rock paintings. The bitter latex, known as Cape aloe, is used as
laxative medicine in Africa and Europe and is considered to have bitter tonic,
antioxidant, anti-inflammatory, antimicrobial, and anticancer properties
[8, 19–23].
The use of A. ferox as a multipurpose
traditional medicine has been translated into several commercial applications
and it is a highly valued plant in the pharmaceutical, natural health, food,
and cosmetic industries.A. ferox is considered South Africa’s main wild
harvested commercially traded species. The finished product obtained from aloe
tapping, aloe bitters, has remained a key South African export product since
1761 when it was first exported to Europe. The aloe tapping industry is the
livelihood of many rural communities and formalization of the industry in the
form of establishment of cooperatives and trade agreements. It has been
suggested that its trade may have an extensive poverty alleviation effect in
Africa [19, 24, 25].
A. ferox has many traditional and documented
medicinal uses. It is most popularly used for its laxative effect and as a
topical application to the skin, eyes, and mucous membranes. Scientific studies
conducted have verified many of the traditional uses. More recently, the
cosmetic industry has shown interest in A. ferox gel [8, 19]. It
has been reported that A. ferox gel contains at least 130 medicinal
agents with anti-inflammatory, analgesic, calming, antiseptic, germicidal,
antiviral, antiparasitic, antitumour, and anticancer effects encompassing all
of the traditional uses and scientific studies done on A. ferox and
its constituents [8, 24–31].
A wide variety of phenolic compounds (chromones,
anthraquinones, anthrone, anthrone-C-glycosides, and other phenolic compounds)
are present within A. ferox and these compounds have been well
documented to possess biological activity [21, 24–31]. The gel
polysaccharides are known to be of the arabinogalactan and rhamnogalacturonan
types. The leaf gel composition still remains unknown and its claimed
biological activities still remain to be investigated. The active ingredient
(purgative principle) is a chemical compound known as Aloin (also called
Barbaloin) [19]. The gel has also been found to be rich in antioxidant
polyphenols, indoles, and alkaloids. Tests carried out have shown that the
nonflavonoid polyphenols contribute to the majority of the total polyphenol
content. With this phytochemical profile, A. ferox leaf gel has been
identified to be very promising in alleviating symptoms associated with/or
prevention of common noncommunicable diseases such as cardiovascular diseases,
cancer, neurodegeneration, and diabetes [32].
The leaves have been reported to contain two juices; the
yellow bitter sap is used as laxative while the white aloe gel is used in
health drinks and skin care products. This purgative drug is used for stomach
complaints, mainly as a laxative to “purify” the stomach and also as a bitter
tonic (amarum) in various digestives and stomachics (such as “Lewensessens” and
“Swedish Bitters”). Usually, a small crystal of the drug (0.05–0.2 g) is taken orally as a laxative.
Half the laxative dose is suggested for arthritis. The fresh bitter sap is
instilled directly against conjunctivitis and sinusitis [24, 25]. It is
well known that bitter substances stimulate the flow of gastric juices and in
so doing improve digestion. The fresh juice emanating from the cut leaf is also
applied on burn wounds [33]. A. ferox is claimed to detoxify the
damaged surface area and exhibit analgesic and anesthetic properties while
promoting new tissue formation (granulation) which fills the wound. It was
demonstrated that A. feroxenriched with aloins can inhibit collagenase and
metalloprotease activity, which can degrade collagen connective tissues. The
effect of A. ferox whole leaf juice on wound healing and skin repair
was investigated in an animal model and its safety was evaluated. The results
showed that the A. ferox whole leaf juice preparation accelerates
wound closure and selectively inhibits microbial growth. No dermal toxicity or
side effects were observed during the experimental period [23].
2.3. Artemisia herba-alba Asso
(Med)—Asteraceae—Wormwood
Artemisia herba-alba is commonly known as wormwood
or desert wormwood (known in Arabic as shih, and as Armoise blanche in French).
It is a greyish strongly aromatic perennial dwarf shrub native to the Northern
Africa, Arabian Peninsula, and Western Asia [34]. A. herba-alba has
been used in folk medicine by many cultures since ancient times. In Moroccan
folk medicine, it is used to treat arterial hypertension and diabetes and in
Tunisia, it is used to treat diabetes, bronchitis, diarrhea, hypertension, and
neuralgias [34, 35]. Herbal tea from A. herba-alba has been used
as analgesic, antibacterial, antispasmodic, and hemostatic agents in folk
medicines [34–39]. During an ethnopharmacological survey carried out among the
Bedouins of the Negev desert, it was found that A. herba-alba was
used to mitigate stomach disorders. This plant is also suggested to be
important as a fodder for sheep and for livestock in the plateau regions of
Algeria where it grows abundantly. It has also been reported that Ascaridae
from hogs and ground worms were killed by the oil of the Libyan A.
herba-alba in a short time [34–42].
Oral administration of 0.39 g/kg body weight of the aqueous extract of the leaves or barks
of A. herba-alba has been documented to produce a significant
reduction in blood glucose level, while the aqueous extract of roots and
methanolic extract of the aerial parts of the plant produce almost no reduction
in blood glucose level. The extract of the aerial parts of the plant seems to
have minimal adverse effect and high LD50 value [19, 30].
Among A. herba-alba phytochemical constituents,
essential oils have been extensively studied, with several chemotypes being
recognized. The variability from the essential oils isolated from A.
herba-alba collected in Algeria, Israel, Morocco, and Spain was revised by
Dob and Benabdelkader [43, 44], but, since then, many other studies have
reinforced its high chemical polymorphism. Recently, fifty components were
identified in A. herba-alba oils, oxygen-containing monoterpenes
being dominant in all cases (72–80%). Camphor (17–33%),α-thujone (7–28%), and
chrysanthenone (4–19%) were the major oil components. Despite the similarity in
main components, three types of oils could be defined: (a) α-thujone : camphor (23–28 : 17–28%),
(b) camphor : chrysanthenone (33 : 12%), and (c) α-thujone : camphor : chrysanthenone (24 : 19 : 19%) [43].
The antifungal activity of Artemisia
herba-alba was found to be associated with two major volatile compounds
isolated from the fresh leaves of the plant. Carvone and piperitone were
isolated from Artemisia herba-alba. The antifungal activity of the
purified compounds carvone and piperitone was estimated to be 5 μg/mL and 2 μg/mL against Penicillium
citrinum and 7 μg/mL and
1.5 μg/mL
against Mucor rouxii, respectively. In another study, the antifungal
activity of the constituents and biological activities of Artemisia
herba-alba essential oils of 25 Moroccan medicinal plants,
including A. herba-alba, against Penicillium
digitatum, Phytophthora citrophthora, Geotrichum citri-aurantii,
and Botrytis cinerea have been reported [42, 43].
2.4. Aspalathus linearis (Brum.f.) R. Dahlg.
(Fabaceae)—Rooibos
Aspalathus linearis, an endemic South African fynbos
species, is cultivated to produce the well-known herbal tea, also commonly
known as rooibos. Its caffeine-free and comparatively low tannin status,
combined with its potential health-promoting properties, most notably
antioxidant activity, has contributed to its popularity and consumer acceptance
globally. The utilization of rooibos has also moved beyond a herbal tea to
intermediate value-added products such as extracts for the beverage, food,
nutraceuticals and cosmetic markets [45–52].
Rooibos is used traditionally throughout Africa in
numerous ways. It has been used as a refreshment drink and as a healthy tea
beverage [8, 19]. It was only after the discovery that an infusion of
rooibos, when administered to her colicky baby, cured the chronic restlessness,
vomiting, and stomach cramps that rooibos became well known as a “healthy”
beverage, leading to a broader consumer base. Many babies since then have been
nurtured with rooibos—either added to their milk or given as a weak brew
[8, 16, 45–52].
Animal studies have suggested that it has potent
antioxidant, immunomodulating, and chemopreventive effects. The plant is rich
in minerals and low in tannins. Among the flavonoids present are the unique
C-glucoside dihydrochalcones: aspalathin and nothofagin and with aspalathin
being the most abundant. In vitrodata has shown that the daily intake of
the alkaline extracts of the red rooibos tea could suppress HIV infections in
the extract, though clinical evaluation has yet to be conducted [8, 45].
There is growing evidence that the flavonoids present in the plant contribute
substantially to a reduction in cardiovascular disease and other ailments
associated with ageing. Recent studies have shown that aspalathin has
beneficial effects on glucose homeostasis in Type 2 diabetes through
stimulating glucose uptake in muscle tissues and insulin secretion from
pancreatic beta-cells [8, 48]. The unfermented rooibos has been found to
have greater chemoprotective effects than the fermented variety [49]. Aspalathin
has free-radical capturing properties and is absorbed through the small
intestine as such [50].
The bronchodilator, antispasmodic, and blood pressure
lowering effects of rooibos tea have been confirmed in
vitro and in vivo. It has also been reported that the antispasmodic
effect of the rooibos is mediated predominantly through potassium ionchannel
activation [51, 52]. There is also increasing evidence of antimutagenic
effects. Animal study suggested the prevention of age-related accumulation of
lipid peroxidases in the brain [19, 26, 47].
Rooibos is becoming more popular in western countries
particularly among health-conscious consumers, due to the absence of alkaloids
and low tannin content. It is also reported to have a high level of
antioxidants such as aspalathin and nothofagin. The antioxidative effect has
also been attributed to the presence of water-soluble polyphenols such as rutin
and quercetin [53]. Rooibos is purported to assist nervous tension, allergies,
and digestive problems.
Rooibos extracts, usually combined with other
ingredients, are available in pill form, but these products fall in the
category of dietary supplements. Recent research has underscored the potential
of aspalathin and selected rooibos extracts such as an aspalathin-enriched
green rooibos extract as antidiabetic agents [54–68]. A patent application for
the use of aspalathin in this context was filed in Japan, while a
placebo-controlled trial application was filed for the use of rooibos extract
as an antidiabetic agent [66]. It is claimed that rooibos extract and a
hetero-dimer containing aspalathin, isolated from rooibos, could be used as a
drug for the treatment of neurological and psychiatric disorders of the central
nervous system [19, 68]. Other opportunities may lie with topical skin
products. Two studies concerning inhibition of COX-2 in mouse skin [67] and
inhibition of mouse skin tumor promotion tend to support the role of the
topical application of rooibos extract. Nonetheless, more research would be
needed to explore its potential in preventing skin cancer in humans [67].
2.5. Centella asiatica (L.) Urb.
(Apiaceae)—Centella
Centella asiatica is a medicinal plant that has been
used since prehistoric times. It has a pan-tropical distribution and is used in
many healing cultures, including Ayurvedic medicine, Chinese traditional
medicine, Kampo (Japanese traditional medicine), and African traditional
medicine [19, 69]. To date, it continues to be used within the structure
of folk medicine and is increasingly being located at the interface between
traditional and modern scientifically oriented medicine. Traditionally, C.
asiatica is used mainly for wound healing, burns, ulcers, leprosy,
tuberculosis, lupus, skin diseases, eye diseases, fever, inflammation, asthma,
hypertension, rheumatism, syphilis, epilepsy, diarrhea, and mental illness and
is also eaten as a vegetable or used as a spice. In Mauritius, the application
of C. asiatica in the treatment of leprosy was reported for the first
time in 1852 while the clinical use of C. asiatica, as a therapeutic agent
suitable for the treatment of leprous lesions, has been documented since 1887
[19].
The active constituents are characterized by their
clinical effects in the treatment of chronic venous disease, wound healing, and
cognitive functions amongst others [19]. C. asiatica contains a
variety of pentacyclic triterpenoids that have been extensively studied.
Asiaticoside and madecassoside are the two most important active compounds that
are used in drug preparations. Both are commercially used mainly as
wound-healing agent, based on their anti-inflammatory effects. One of the main
active constituents of C. asiatica is the ursane-type triterpene
saponin, asiaticoside, which is responsible for wound healing properties
[19, 70, 71] and is known to stimulate type 1 collagen synthesis in
fibroblast cells [72]. Plants collected from various geographical regions and
locations in India, Madagascar, Malaysia, Sri Lanka, Andaman Islands, and South
Africa have yielded concentrations of asiaticoside ranging from 0.006 to 6.42%
of dry weight [73, 74]. C. asiatica also contains several other
triterpene saponins. Madecassoside always co-occurs with asiaticoside as a main
compound and other saponins have been reported, such as asiaticosides A to G,
centelloside, brahmoside, and many others [19, 75]. Madagascar plays a
major role in C. asiatica trade. It is the first producer of C.
asiaticaproducts worldwide and due to a higher Asiaticoside content of dried
leaves, Malagasy origin is appreciated by industry [9].
The ethyl acetate fraction of C. asiatica has
been reported to increase the effect of the i.p. administrated
antiepileptic drugs phenytoin, valproate, and gabapentin [75, 76] and was
found to decrease the pentylenetetrazol- (PTZ-) kindled induced seizures in
rats [75, 77]. This effect might be due to an increase in
gamma-aminobutyric acid (GABA) levels caused by the extract as reported by
Chatterjee et al. [78]. The neuroprotective properties of the plant in
monosodium glutamate treated rats were investigated by Ramanathan et al. [79].
The general behavior, locomotor activity, and the CA1 region of the hippocampus
were protected byC. asiatica extracts. The levels of catalase, superoxide
dismutase, and lipid peroxidase in the hippocampus and striatum were improved
indicating a neuroprotective property of the extract [74]. Additionally, the
effect of C. asiatica on cognitive function of healthy elderly
volunteer was evaluated in a randomized, placebo-controlled, double-blind study
involving 28 healthy elderly participants. The subjects have received the plant
extract at various doses ranging from 250 to 500 and 750 mg once daily for 2 months, and cognitive
performance and mood modulation were assessed. It was found that high dose of
the plant extract enhanced working memory and increased N100 component
amplitude of event-related potential. Improvements of self-rated mood were also
found following the C. asiatica treatment. The high dose of C.
asiatica used in the study was suggested to increase calmness and alertness
after 1 and 2 months of treatment. However, the precise mechanism(s) underlying
these effects still require further investigation [72].
2.6. Catharanthus roseus (L.) G. Don
(Apocynaceae)—Madagascan Periwinkle
Catharanthus roseus (Madagascar periwinkle) is a
well-known medicinal plant that has its root from the African continent. The
interest in this species arises from its therapeutic role, as it is the source
of the anticancer alkaloids vincristine and vinblastine, whose complexity
renders them impossible to be synthesized in the laboratory; the leaves of this
species are still, today, the only source
[8, 12, 19, 80]. C. roseus originates from Madagascar
but now has a wide distribution throughout the tropics, and the story on the
traditional utilisation of this plant can be retraced to Madagascar where
healers have been using it extensively to treat panoply of ailments. It is
commonly used in traditional medicine as a bitter tonic, galactogogue, and
emetic. Application for treatment of rheumatism, skin disorders, and venereal
diseases has also been reported [8, 10, 19].
C. roseus has been found to contain a plethora of
phytochemicals (as many as 130 constituents) and the principal component is
vindoline (up to 0.5%). Other biologically active compounds are serpentine,
catharanthine, ajmalicine (raubasine), akuammine, lochnerine, lochnericine, and
tetrahydroalstonine. The plant is also rich in bisindole alkaloids; vindoline
and catharanthine are found in very small amounts: vincristine (=leurocristine)
in up to 3 g/t of
dried drug and vinblastine (=vincaleucoblastine) in a slightly larger amount
[8,12, 19, 81–84].
The oral administration of water-soluble fractions and
ethanolic extracts of the leaves have been found to show significant
dose-dependent reduction in the blood sugar at 4 h by 26.2, 31.4, 35.6, and 33.4%, respectively, in normal rats. In
addition, oral administration of 500 mg/kg 3.5 h before oral glucose tolerance test (10 mg/kg) and 72 h after STZ administration (50 mg/kg IP) in rats showed significant
antihyperglycaemic effects. No gross behavioural changes and toxic effects were
observed up to 4 mg/kg IP [85].
Extract at dose of 500 mg/kg given orally for 7 and 15 days showed 48.6 and 57.6%
hypoglycemic activity, respectively. Prior treatment at the same dose
for 30 days provided complete protection against streptozotocin (STZ) challenge
(75 mg/kg/i.p. × 1). Enzymatic activities of
glycogen synthase, glucose 6-phosphate-dehydrogenase, succinate dehydrogenase,
and malate dehydrogenase were decreased in liver of diabetic animals in
comparison to normal ones and were significantly improved after treatment with
extract at dose of 500 mg/kg p.o. for 7 days. Results indicate increased metabolization of
glucose in treated rats. Increased levels of lipid peroxidation measured
as 2-thiobarbituric acid reactive substances indicative of oxidative stress in
diabetic rats were also normalized by treatment with the extract [2].
Vincristine and Vinblastine are antimitotics as they bind
to tubulin and prevent the formation of microtubules that assist in the
formation of the mitotic spindle; in this way, they block mitosis in the
metaphase. These alkaloids are highly toxic; they both have neurotoxic activity
(especially vincristine) because the microtubule assembly also plays a role in
neurotransmission. Their peripheral neurotoxic effects are neuralgia, myalgia,
paresthesia, loss of the tendon reflexes, depression, and headache, and their
central neurotoxic effects are convulsive episodes and respiratory difficulties.
Other side effects are multiple and include alopecia, gastrointestinal distress
including constipation, ulcerations of the mouth, amenorrhoea, and azoospermia
[10,19, 80, 84, 85].
Recently, new phenolics in different plant parts (leaves,
stems, seeds, and petals), including flavonoids and phenolic acids, were
reported [10, 19, 82]. In addition, a phytochemical study concerning
several classes of metabolites was performed and bioactivity was assessed
[81–84]. The high antioxidant potential of C. roseuswas
demonstrated in vitro using the radicals DPPH, superoxide, and nitric
oxide [19, 81].
2.7. Cyclopia genistoides (L.) Vent.
(Fabaceae)—Honeybush
Cyclopia genistoides is an indigenous herbal tea to
South Africa and considered as a health food. Traditionally, the leafy shoots
and flowers were fermented and dried to prepare tea. It has also been used
since early times for its direct positive effects on the urinary system and is
valued as a stomachic that aids weak digestion without affecting the heart. It
is a drink that is mainly used as a tea substitute because it contains no
harmful substances such as caffeine. It is one of the few indigenous South
African plants that made the transition from the wild to a commercial product
during the past 100 years. Research activities during the past 20 years have
been geared towards propagation, production, genetic improvement, processing,
composition, and the potential for value adding [19, 25–31, 45].
A decoction of honeybush was used as a restorative and as
an expectorant in chronic catarrh and pulmonary tuberculosis [25–31, 86].
Drinking an infusion of honeybush apparently also increases the appetite, but
no indication is given of the specific species [87]. According to Marloth [88],
honeybush was praised by many colonists as being wholesome, valuing it as a
stomachic that aids weak digestion without producing any serious stimulating
effects on the heart. It also alleviates heartburn and nausea [25–31].
Anecdotal evidence suggests that it stimulates milk production in
breast-feeding women and treats colic in babies [89].
Modern use of honeybush is prepared as an infusion and at
times taken together with rooibos. The tea bags usually contain a larger
percentage of rooibos than honeybush. Parts of other indigenous South African
plants and fruits mixed with honeybush include dried buchu leaves, pieces of
African potato (Hypoxis hemerocallidea) corms, and dried marula (Sclerocarya
birrea) fruit. The ready-to-drink honeybush iced tea market is not developed to
the same extent as that of rooibos, while honeybush “espresso,” amongst others,
has not been tried [10, 19].
Honeybush is well known as caffeine-free, low tannin,
aromatic herbal tea with a wealth of polyphenolic compounds associated with its
health-promoting properties. The exact biologically active phytochemicals from
honeybush are unknown, but the beneficial effects have been justified based on
phenolic compounds. The major compounds, present in all species analyzed to
date, are the xanthones, mangiferin and isomangiferin, and the flavanone,
hesperidin. Recently, two benzophenone derivatives 3-C-β-glucosides of maclurin
and iriflophenone were isolated for the first time from C. genistoides and
were tested for pro-apoptotic activity toward synovial fibroblasts isolated
from rheumatoid arthritis patients. The strongest proapoptotic activity was
obtained for isomangiferin and iriflophenone 3-C-β-glucoside, which were not
previously evaluated as potential antiarthritic agents. Proapoptotic effects
were recorded for mangiferin and hesperidin, which are major polyphenols in all
commercially used honeybush plants. Recently, C. genistoides has
attracted much attention for the production of an antioxidant product high in
mangiferin content. The latter and its sustainability make C.
genistoides an attractive source of mangiferin. Other potential
applications are for the prevention of skin cancer, alleviation of menopausal
symptoms, and lowering of blood glucose levels [10, 19,45, 90].
2.8. Harpagophytum procumbens (Burch.) DC.
(Pedaliaceae)—Devil’s Claw
Harpagophytum procumbens is native to the red sand
areas in the Transvaal of South Africa, Botswana, and Namibia. It has spread
throughout the Kalahari and Savannah desert regions. The indigenous San and
Khoi peoples of Southern Africa have used Devil’s Claw medicinally for
centuries, if not millennia [8, 19, 91].Harpagophytum
procumbens has an ancient history of multiple indigenous uses and is one
of the most highly commercialized indigenous traditional medicines from Africa,
with bulk exports mainly to Europe where it is made into a large number of
health products such as teas, tablets, capsules, and topical gels and patches
[92].
Traditional uses recorded include allergies, analgesia,
anorexia, antiarrhythmic, antidiabetic, antiphlogistic, antipyretic, appetite
stimulant, arteriosclerosis, bitter tonic, blood diseases, boils (topical),
childbirth difficulties, choleretic, diuretic, climacteric (change of life) problems,
dysmenorrhea, dyspepsia, edema, fever, fibromyalgia, fibrositis,
gastrointestinal disorders, headache, heartburn, indigestion, liver and gall
bladder tonic, malaria, migraines, myalgia, neuralgia, nicotine poisoning,
sedative, skin cancer (topical), skin ulcers (topical), sores (topical),
tendonitis, urinary tract infections, and vulnerary for skin injuries. The
major clinical uses for Devil’s claw are as an anti-inflammatory and analgesic
in joint diseases, back pain, and headache. Evidence from scientific studies in
animals and humans has resulted in widespread use of standardized Devil’s claw
as a mild analgesic for joint pain in Europe [8, 12, 19, 91–95].
Chemical constituents according to the published
literature include potentially (co)active chemical constituents: iridoid
glycosides (2.2% total weight) harpagoside (0.5–1.6%), 8-p-coumaroylharpagide,
8-feruloyl-harpagide, 8-cinnamoylmyoporoside, pagoside, acteoside,
isoacteoside, 6′-O-acetylacteoside,
2,6-diacetylacteoside, cinnamic acid, caffeic acid, procumbide, and
procumboside. The constituent 6-acetylacteoside, being present inH.
procumbens and absent in H. zeyheri, allows users to distinguish
between the two species. Other compounds include flavonoids, fatty acids,
aromatic acids, harpagoquinone, stigmasterol, beta-sitosterol, triterpenes,
sugars (over 50%), and gum resins [8, 12, 19, 91–95].
Harpagoside isolated from H. procumbens varies within the plant and
is the highest in the secondary tubers, with lower levels in the primary roots.
The flowers, stems, and leaves appear to be devoid of active compounds. Iridoid
glycosides isolated from H. procumbens tend to show dose-dependent
anti-inflammatory and analgesic effects equivalent to phenylbutazone; they are
apparently inactivated by gastric acids. Harpagoside is the most effective when
given parenterally and loses potency markedly when given by mouth; enteric
coated preparations might maintain efficacy despite exposure to gastric acids.
Harpagoside has also been reported to inhibit arachidonic acid metabolism
through both cyclooxygenase and lipoxygenase pathways [9, 91–96].
There are varying and contradictory opinions regarding
the anti-inflammatory and analgesic effects of Devil’s claw in the treatment of
arthritic diseases and low back pain. The controversy revolves around the
active constituent of Devil’s claw and its mechanism of action, as it appears
to be different than that of nonsteroidal anti-inflammatory drugs (NSAID). The
evidence from scientific studies in animals and humans has resulted in
widespread use of standardized Devil’s claw as a mild analgesic for joint pain
in Europe [8, 12, 19, 91–96].
Several clinical studies have been performed to determine
the effectiveness of H. procumbens for its use as
anti-inflammatory, general analgesic (commonly for lower back pain), and
anti-rheumatic agent. To determine the effectiveness on lower back
pain, Harpagophytum extract WS1351 was administered in two daily
doses of 600 and 1200 mg containing 50 and 100 mg of harpagoside, respectively, and compared to placebo. This
randomized double-blind study took place over 4 weeks and subjects () with
chronic susceptibility to back pain and current exacerbations with intense pain
were included. Out of 183 subjects that completed the trial, six in the 600 mg and 10 in the 1200 mg were reported “pain-free” without
using Tramadol (rescue pain medication). However, data analyses suggested that
the 600 mg group
reaped more benefits where less severe pain and no radiation or neurological
deficit was present. The patients with more severe pain tended to use
more Tramadol but not to the maximum permitted dose [92].
2.9. Momordica charantia Linn.
(Cucurbitaceae)—Bitter Melon
Momordica charantia, also known as bitter melon, is a
tropical vegetable grown throughout Africa. The leaf may be made into a tea
called “cerassie,” and the juice, extracted from the various plant parts (fruit
pulp, seeds, leaves, and whole plant), is very common folklore remedy for
diabetes [2]. M. charantia has a long history of use as a folklore
hypoglycemic agent where the plant extract has been referred to as vegetable
insulin [97].
Several active compounds have been isolated from M.
charantia, and some mechanistic studies have been done [98–101]. Khanna et al.
[102] have reported the isolation from fruits, seeds, and tissue culture of
seedlings, of “polypeptide-p,” a 17-amino acid, 166-residue polypeptide which
did not cross-react in an immunoassay for bovine insulin. Galactose binding
lectin with a molecular weight of 124,000 isolated from the seeds of M.
charantia has been evaluated for its antilipolytic and lipogenic
activities in isolated rat adipocytes and found comparable to insulin
[103, 104]. Extracts of fruit pulp, seed, leaves, and whole plant
of M. charantia have shown hypoglycemic effect in various animal
models [103, 104]. Karunanayake et al. [105] found a significant
improvement in glucose tolerance and hyperglycemia when the fruit juice of
bitter melon was administered orally to rats. Fresh as well as freeze-dried M.
charantia was found to improve glucose tolerance significantly in normal
rats and noninsulin dependent diabetics (NIDDM) [105–108]. It was hypothesized
that M. charantiafruit contains more than one type of hypoglycemic
component. These may include an active principle called “charantin,” a
homogenous mixture of β-sitosterol-glucoside and
2-5-stigmatadien-3-β-ol-glucoside that can produce a hypoglycemic effect in
normal rabbits [109]. Shibib et al. [110] in a study administered the ethanolic
extract of the fruit of bitter melon to STZ diabetic rats orally at a dose
equivalent to 200 mg extract
per kg body weight. Ninety minutes after the administration, they found that
blood glucose levels had been reduced by 22%. The glucogenic
enzymes-glucose-6-phosphatase and fructose 1, 6-bisphosphatase in the
liver were also depressed. Further evidence for a beneficial chronic effect is
that an improvement in both glucose tolerance and fasting blood glucose levels
was observed in 8 NIDDM patients following 7 weeks of daily consumption of
powered M. charantia fruit [97]. Although some authors have indicated
that the effect of M. charantia is not associated with an increase in
circulating insulin, Welihinda et al. [111] and Welihinda and Karunanayake
[112] demonstrated that an aqueous extract from the fruit of M.
charantia was a potent stimulator of insulin release from β-cell-rich
pancreatic islets isolated from obese-hyperglycaemic mice. Recently, Matsuura
et al. [113] have isolated an α-glucosidase inhibitor from M.
charantia seeds which can be a potential drug therapy for postprandial
hyperglycaemia (PPHG). However, Dubey et al. [104] found that the aqueous,
methanolic, and saline extracts of M. charantia produced a
significant hypoglycaemic effect in rats. In addition, the methanol and saline
extracts also prevented adrenaline-induced hyperglycaemia.
When tested on laboratory animals, bitter melon has shown
hypoglycaemic as well as antihyperglycaemic activities. Polypeptide-p isolated
from fruit, seeds, and tissue of bitter melon showed potent hypoglycaemic
effects when administered subcutaneously to gerbils, langurs, and humans. The
aqueous extracts of M. charantia improved oral glucose tolerance test
(OGTT) after 8 h in normal
mice and reduced hyperglycaemia by 50% after 5 h in STZ diabetic mice. In
addition, chronic oral administration of extract to normal mice for 13 days
improved OGTT while no significant effect was seen on plasma insulin levels. We
recently reported thatM. charantia fruit extracts have a direct impact on
transport of glucose in vitro [99, 114–117].
2.10. Pelargonium sidoides DC.
(Geraniaceae)—Umckaloabo
Pelargonium sidoides is native to the coastal
regions of South Africa, and available ethnobotanical information shows that
the tuberous P. sidoides is an important traditional medicine with a
rich ethnobotanical history [19].
P. sidoides root extract EPs 7630, also known as
Umckaloabo, is a herbal remedy thought to be effective in the treatment of
acute respiratory infections. There are numerous studies about P. sidoides and
respiratory tract infections [118, 119]. These studies showed that P.
sidoides may be effective in alleviating symptoms of acute rhinosinusitis
and the common cold in adults, but doubt exists. It may be effective in relieving
symptoms of acute bronchitis in adults and children and sinusitis in adults
[118]. EPs 7630 significantly reduced bronchitis symptom scores in patients
with acute bronchitis by day 7 [119]. No serious adverse events were reported.
EPs 7630 has a positive effect on phagocytosis, oxidative burst, and
intracellular killing of cells [120–125]. P. sidoides extract
modulates the production of secretory immunoglobulin A in saliva, both
interleukin-15 and interleukin-6 in serum, and interleukin-15 in the nasal
mucosa [19, 126].
In one research, P. sidoides was documented to
represent an effective treatment against common cold. It was reported to
significantly reduce the severity of symptoms and shortens the duration of the
common cold compared with placebo. Because of these effects, the authors have
aimed at establishing whether or not P. sidoides could affect the
asthma attack frequency after upper respiratory tract viral infection. Results
for some 20 clinical trials have been published, 7 of which were observational
studies and the remaining 13 were randomized, double-blind, and
placebo-controlled. For 6 of those 13 trials, only preliminary results have
been published. All trials have been carried out using EPs 7630 in liquid or
solid forms. The data derived from these trials has been evaluated in 2 reviews
[19, 118, 119].
Antibacterial activity of extracts and isolated
constituents of P. sidoides was evaluated by Kayser [127] against
three gram-positive and five gram-negative bacteria. Most compounds exhibited
antibacterial activities. Further investigations by Lewu et al. [128] have
supported these findings. EPs 7630 has been found to show a synergistic
indirect antibacterial effect in group A-streptococci (GAS) through inhibition
of bacterial adhesion to human epithelial cells as well as induction of
bacterial adhesion to buccal epithelial cells [8, 129]. Wittschier et al.
[130] and Beil and Kilian [131] confirmed the antiadhesive effect of EPs 7630
for Helicobacter pylorigrowth and adhesion to gastric epithelial cells. Umckaloabo
has been documented to significantly stimulate phagocytosis, oxidative burst,
and intracellular killing whichwas also enhanced [120–125]. It was proposed
that modulation of epithelial-cell bacteria interaction through EPs 7630 may
protect mucous membranes from microorganisms evading host defense mechanisms.
These findings tend to provide a rationale for the treatment of upper
respiratory tract infections with EPs 7630 [131, 132].
Taylor et al. [133] have recently established the
antimycobacterial activity for hexane extracts of roots of P.
reniforme and P. sidoides. Gödecke et al. [134] have reported no
significant effect on the bacterial growth of two strains of mycobacteria by
extracts and fractions of P. sidoides. An antitubercular effect may thus
be achieved indirectly by stimulation of immune response. This assumption was
supported by Mativandlela et al. [135] as none of the compounds isolated
from P. sidoides showed any significant activity against M.
tuberculosis.
Kayser et al. [136] have investigated into extracts and
isolated constituents of P. sidoides for their effects on nonspecific
immune functions in various bioassays. They found indirect activity, possibly
through activation of macrophage functions. Activation was confirmed through the
presence of tumor necrosis factor (TNF-alpha) and inorganic nitric oxides
(iNO). Kolodziej [137, 138] also observed TNF-inducing potencies for EPs
7630 as well as interferon-like activities. Koch et al. [139] observed
interferon- (IFN-) beta production increased and natural killer cell mediated
cytotoxicity enhanced in MG-63 human osteosarcoma cells preincubated with
Umckaloabo [19, 139]. Kolodziej [137, 138] investigated
polyphenol-containing extracts of P. sidoides and simple phenols,
flavan-3-ols, proanthocyanidins, and hydrolysable tannins for gene expressions
(iNOS, IL-1, IL-10, IL-12, IL-18, TNF-alpha, and IFN-alpha/gamma). All extracts
and compounds were capable of enhancing the iNOS and cytokine mRNA levels in
parasitised cells.
3. Discussion
Medicinal plants are an integral part of the African
healthcare system since time immemorial. Interest in traditional medicine can
be explained by the fact that it is a fundamental part of the culture of the
people who use it and also due to the economic challenge: on one side, the
pharmaceutical drugs are not accessible to the poor and on the other side, the
richness and diversity of the fauna and flora of Africa are an inexhaustible
source of therapies for panoply of ailments [140]. Nonetheless, there is still
a paucity of clinical evidence to show that they are effective and safe for
humans. Without this information, users of traditional medicinal plants in
Africa and elsewhere remain skeptical about the value of such therapies. This
denies people the freedom to choose plants that are potentially less costly and
are more accessible. Another issue concerning the use of botanical remedies is
the need to understand the safety of these therapies. For these reasons,
information about efficacy and safety of traditional medicines is urgently
required. The present paper has endeavoured to overview just a few common
medicinal plants from the African continent which have short- as well as
long-term potential to be developed as future phytopharmaceuticals to treat
and/or manage panoply of infectious and chronic conditions. Within the
framework of enhancing the significance of traditional African medicinal
plants, aspects such as traditional use, phytochemical composition, and in
vitro, in vivo, and clinical studies pertaining to the use of these
plants have been explored.
During the last few decades, it has become evident that
there exists a plethora of plants with medicinal potential and it is
increasingly being accepted that the African traditional medicinal plants might
offer potential template molecules in the drug discovery process. Many of the
plants presented here show very promising medicinal properties thus warranting
further clinical investigations. Nonetheless, only few of them have robust
scientific and clinical proofs and with a significant niche market
(e.g., Aloe ferox, Artemisia afra, Aspalathus linearis,Centella
asiatica, and Pelargonium sidoides) and a lot more have yet to be explored
and proved before reaching the global market [7, 8, 12, 19].
In the light of modern science, significant efforts
should be geared to identify and characterize the bioactive constituents from
these plants. Indeed, the discovery of therapeutic compounds from traditional
medicinal plant remedies remains a medically and potentially challenging task.
For adventure in such an attempt, highly reproducible and robust innovative
bioassays are needed in view of our limited understanding of the multifactorial
pathogenicity of diseases. Innovative strategies to improve the process of
plant collection are needed, especially with the legal and political issues
surrounding benefit-sharing agreements. Since drug discovery from medicinal
plants has traditionally been so time-consuming, it is also of uttermost
importance for investigators to embark and devise new automated bioassays with
special emphasis on high throughput procedures that can screen, isolate, and
process data from an array of phytochemicals within shorter time lapse for
product development. Additionally, these procedures should also attempt to rule
out false positive hits and dereplication methods to remove nuisance compounds
[7].
Nonetheless, despite continuous comprehensive and
mechanism-orientated evaluation of medicinal plants from the African flora,
there is still a dearth of literature coming from the last decade’s
investigations addressing procedures to be adopted for quality assurance,
authentication, and standardization of crude plant products. Appropriate
standardization could be achieved via proper management of raw material,
extraction procedures, and final product formulation. Without effective quality
control, consistency and market value of the herbal product may be compromised.
Indeed, one of the main constraints to the growth of a modern African
phytomedicine industry has also been identified as the lack of proper
validation of traditional knowledge and also the lack of technical
specifications and quality control standards. This makes it extremely difficult
for buyers, whether national or international, to evaluate the safety and efficacy
of plants and extracts, or compare batches of products from different places or
from year to year. This is in marked contrast with Europe and Asia where
traditional methods and formulations have been recorded and evaluated both at
the local and national levels. This would also tend to justify why the level of
trade of phytomedicines in Asia and Europe is blooming more than those in
Africa [7].
It is also imperative that potential risk factors, for
example, the contamination of medicinal plant products with heavy metals from
African traditional medicine products, be addressed and that regulatory
guidelines are not only carefully developed but also enforced. Controlled
growth (under GACP) and processing environments (under Good Manufacturing
Practice) need to ensure that contamination of medicinal plant material is kept
to a minimum. For the medicinal plant industry, cultivated plant material is
preferred as it is easier to control the supply chain plus contamination is
nominal [141]. On the other hand, proper identification of a medicinal plant
material is fundamental to the quality control process; it must be established
unmistakably that the source of the plant material is genuine. Following this,
microbial contamination (fungal, bacterial, and any potential human pathogens)
must be checked during the stages of processing of the material. Chemical,
pharmacological, and toxicological evaluations, conducted according to the
principles of Good Laboratory Practices (GLPs), will certify the bioactive properties
of the material undergoing processing. These tests also are often the
predictors of safety of the products manufactured. Clinical safety and efficacy
will need to be established through exhaustive and usually lengthy trials
during the early stages of the development of a therapeutic agent. After that,
so long as the standard operating procedures are adhered to, then the unit
dosage forms produced will be considered safe. Notwithstanding this, quality
assurance procedures must be instituted so that the products coming from the
factory are of good quality, safety, and efficacy [142]. To this effect, during
the development stage, product standardization, quality control and assurance,
double-blind, placebo-controlled, and randomized clinical controlled trials
using standardized products or products containing pure plant extracts are
essential components that need to be perfected in order to translate the
potential of African botanicals into a reality for human to benefit
[7, 142].
4. Conclusions
It is evident from the literature that there is currently
a renewed interest in African-plant-based medicines in the prevention and cure
of various pathologies. Medicinal plants still play an important role in
healthcare system in African countries. Nonetheless, there are still many major
challenges that need to be overcome and addressed for its full potential to be
realized as the effective treatment of diseases with plant products has not
been validated thoroughly with robust scientific criteria to compete with
existing conventional therapies. Additionally, other issues that need to be
addressed are that of access and benefit sharing following the Nagoya
agreement. Local laws need to be TRIPS compliant if trade of African herbal
products is to increase, and, at the same time, issues of sustainable use and
development of plant products need to be addressed.
References
1. WHO, Fact sheet N°134,
2008, http://www.who.int/mediacentre/factsheets/2003/fs134/en/.
2. A. Gurib-Fakim, “Medicinal plants: traditions of yesterday
and drugs of tomorrow,” Molecular Aspects of Medicine, vol. 27, no. 1, pp.
1–93, 2006. View at Publisher · View at Google
Scholar · View at Scopus
3. V. Chintamunnee and M. F. Mahomoodally, “Herbal
medicine commonly used against infectious diseases in the tropical island of
Mauritius,” Journal of Herbal Medicine, vol. 2, pp. 113–125, 2012.
4. H. Nunkoo and M. F. Mahomoodally,
“Ethnopharmacological survey of native remedies commonly used against
infectious diseases in the tropical island of Mauritius,” Journal of
Ethnopharmacology, vol. 143, no. 2, pp. 548–564, 2012.
5. S. Shohawon and M. F. Mahomoodally, “Complementary and
alternative medicine use among Mauritian women,” Complementary Therapies
in Clinical Practice, vol. 19, no. 1, pp. 36–43, 2013.
6. Aone Mokaila,
2001, http://www.blackherbals.com/atcNewsletter913.pdf.
7. A. Gurib-Fakim and M. F. Mahomoodally, “African flora
as potential sources of medicinal plants: towards the chemotherapy of major
parasitic and other infectious diseases- a review,” Jordan Journal of
Biological Sciences, vol. 6, pp. 77–84, 2013.
8. A. Gurib-Fakim, T. Brendler, L. D. Phillips, and L. N.
Eloff, Green Gold—Success Stories Using Southern African Plant Species,
AAMPS Publishing, Mauritius, 2010.
9. C. Manach, A. Scalbert, C. Morand, C. Rémésy, and L.
Jiménez, “Polyphenols: food sources and bioavailability,” American Journal
of Clinical Nutrition, vol. 79, no. 5, pp. 727–747, 2004. View at Scopus
10. B. M. Abegaz, B. T. Ngadjui, G. N. Folefoc et al.,
“Prenylated flavonoids, monoterpenoid furanocoumarins and other constituents
from the twigs of Dorstenia elliptica (Moraceae),”Phytochemistry,
vol. 65, no. 2, pp. 221–226, 2004. View at Publisher · View at
Google Scholar · View at Scopus
11. N. R. Farnsworth, O. Akerele, A. S. Bingel, D. D.
Soejarto, and Z. Guo, “Medicinal plants in therapy,”Bulletin of the World
Health Organization, vol. 63, no. 6, pp. 965–981, 1985. View at Scopus
12. Association of African Medicinal Plants Standards
(AAMPS), http://www.aamps.org/.
13. S. E. Atawodi, “Antioxidant potential of African
medicinal plants,” African Journal of Biotechnology, vol. 4, no. 2, pp.
128–133, 2005. View at Scopus
14. S. O. Okoro, A. H. Kawo, and A. H. Arzai,
“Phytochemical screening, antibacterial and toxicological activities
of Acacia senegal extracts,” Bayero Journal of Pure and Applied
Sciences, vol. 5, no. 1, pp. 163–1170, 2011.
15. R. Jain, P. Sharma, T. Bhagchandani, and S. C. Jain,
“Phytochemical investigation and antimicrobial activity of Acacia senegal root
heartwood,” Journal Pharmaceutical Research, vol. 5, pp. 4934–4938, 2012.
16. A. Gurib-Fakim and M. J. Kasilo, Promoting African
Medicinal Plants through an African Herbal Pharmacopoeia. Special Issue 14:
Decade of African Traditional Medicine, 2001–2010.
17. B. S. Aliyu, Common Ethnomedicinal Plants of the
Semiarid Regions of West Africa, Triumph Publishing, Kano, Nigeria, 2006.
18. S. O. Okoro, A. H. Kawo, and A. H. Arzai,
“Phytochemical screening, antibacterial and toxicological activities
of Acacia senegal extracts,” Bayero Journal of Pure and Applied
Sciences, vol. 5, no. 1, pp. 163–170, 2011.
19. T. Brendler, L. N. Eloff, A. Gurib-Fakim, and L. D.
Phillips, African Herbal Pharmacopeia, AAMPS Publishing, Mauritius, 2010.
20. B.-E. van Wyk, “A broad review of commercially
important southern African medicinal plants,” Journal of
Ethnopharmacology, vol. 119, no. 3, pp. 342–355, 2008. View at
Publisher · View at Google Scholar ·View at Scopus
21. B. E. Van Wyk and M. Wink, Medicinal Plants of
the World: An Illustrated Scientific Guide to important Medicinal Plants and
Their Uses, Briza Publications, Pretoria, South Africa, 2004.
22. Y. Jia, G. Zhao, and J. Jia, “Preliminary evaluation:
the effects of Aloe ferox Miller and Aloe arborescens Miller on wound
healing,” Journal of Ethnopharmacology, vol. 120, no. 2, pp. 181–189,
2008. View at Publisher · View at Google
Scholar · View at Scopus
23. W. Chen, B.-E. Van Wyk, I. Vermaak, and A. M.
Viljoen, “Cape aloes—a review of the phytochemistry, pharmacology and
commercialisation of Aloe ferox,” Phytochemistry Letters, vol. 5, no.
1, pp. 1–12, 2012.View at Publisher · View at Google
Scholar · View at Scopus
24. A. Melin, A bitter pill to swallow: a case study
of the trade & harvest of Aloe ferox in the Eastern Cape, South Africa
[M.S. thesis], Imperial College, 2009.
25. B. E. Van Wyk and N. Gericke, People's Plants: A
Guide to Useful Plants of Southern Africa, Briza Publications, Pretoria, South
Africa, 2000.
26. B.-E. van Wyk, “A broad review of commercially
important southern African medicinal plants,” Journal of
Ethnopharmacology, vol. 119, no. 3, pp. 342–355, 2008. View at
Publisher · View at Google Scholar ·View at Scopus
27. B. E. Van Wyk and G. F. Smith, Guide to the
Aloes of South Africa, Briza Publications, Pretoria, South Africa, 1996.
28. B. E. Van Wyk and G. F. Smith, Guide to the
Aloes of South Africa, Briza Publications, Pretoria, South Africa, 2004.
29. B. E. Van Wyk, B. Van Oudtshoorn, and N.
Gericke, Medicinal Plants of South Africa, Briza Publications, Pretoria,
South Africa, 2nd edition, 2009.
30. B.-E. Van Wijk, M. C. B. Van Rheede Van Oudtshoorn,
and G. F. Smith, “Geographical variation in the major compounds of Aloe
ferox leaf exudate,” Planta Medica, vol. 61, no. 3, pp. 250–253,
1995. View at Scopus
31. B. E. Van Wyk, A. Yenesew, and E. Dagne,
“Chemotaxonomic survey of anthraquinones and pre-anthraquinones in roots of
Aloe species,” Biochemical Systematics and Ecology, vol. 23, no. 3, pp.
267–275, 1995. View at Publisher · View at Google
Scholar · View at Scopus
32. T. L. Du, F. H. Van Der Westhuizen, and L. Botes,
“Aloe ferox leaf gel phytochemical content, antioxidant capacity, and
possible health benefits,” Journal of Agricultural and Food Chemistry,
vol. 55, no. 17, pp. 6891–6896, 2007. View at Publisher · View
at Google Scholar · View at Scopus
33. F. A. Andersen, “Final report on the safety
assessment of Aloe andongensis extract, Aloe
andongensis leaf juice, Aloe arborescens leaf extract, Aloe
arborescens leaf juice, Aloe arborescens leaf
protoplasts, Aloe barbadensis flower extract, Aloe
barbadensis leaf, Aloe barbadensis leaf extract, Aloe
barbadensis leaf juice,Aloe barbadensis leaf polysaccharides, Aloe
barbadensis leaf water, Aloe ferox ferox leaf
extract,”International Journal of Toxicology, vol. 26, no. 2, pp. 1–50,
2007. View at Publisher · View at Google
Scholar · View at Scopus
34. R. Segal, I. Feuerstein, and A. Danin, “Chemotypes
of Artemisia herba-alba in Israel based on their sesquiterpene
lactone and essential oil constitution,” Biochemical Systematics and
Ecology, vol. 15, no. 4, pp. 411–416, 1987. View at Scopus
35. A. Ziyyat, A. Legssyer, H. Mekhfi, A. Dassouli, M.
Serhrouchni, and W. Benjelloun, “Phytotherapy of hypertension and diabetes in
oriental Morocco,” Journal of Ethnopharmacology, vol. 58, no. 1, pp.
45–54, 1997. View at Publisher · View at Google
Scholar · View at Scopus
36. A. Tahraoui, J. El-Hilaly, Z. H. Israili, and B.
Lyoussi, “Ethnopharmacological survey of plants used in the traditional
treatment of hypertension and diabetes in south-eastern Morocco (Errachidia
province),”Journal of Ethnopharmacology, vol. 110, no. 1, pp. 105–117,
2007. View at Publisher · View at Google Scholar · View
at Scopus
37. N.-A. Zeggwagh, O. Farid, J. B. Michel, and M.
Eddouks, “Cardiovascular effect of Artemisia herba alba aqueous
extract in spontaneously hypertensive rats,” Methods and Findings in
Experimental and Clinical Pharmacology, vol. 30, no. 5, pp. 375–381,
2008. View at Publisher · View at Google
Scholar · View at Scopus
38. M. Laid, M.-E. F. Hegazy, A. A. Ahmed, K. Ali, D.
Belkacemi, and S. Ohta, “Sesquiterpene lactones from Algerian Artemisia
herba-alba,” Phytochemistry Letters, vol. 1, no. 2, pp. 85–88,
2008. View at Publisher ·View at Google Scholar · View at
Scopus
39. J. Friedman, Z. Yaniv, A. Dafni, and D. Palewitch, “A
preliminary classification of the healing potential of medicinal plants, based
on a rational analysis of an ethnopharmacological field survey among Bedouins
in the Negev Desert, Israel,” Journal of Ethnopharmacology, vol. 16, no.
2-3, pp. 275–287, 1986.View at Scopus
40. F. Fenardji, M. Klur, C. Fourlon, and R. Ferrando,
“White Artemisia (Artemisia herba alba L.),” Revue
d"elevage et de medecine veterinaire des pays tropicaux, vol. 27, no. 2,
pp. 203–206, 1974. View at Scopus
41. A. Benmansur, S. A. Taleb-Bendiab, N. Mashev, and G.
Vasilev, “Studies on the chemical composition ofArtemisia (Artemisia
herba-alba),” Bolgarskoi Akademii Nauk, vol. 43, no. 8, pp. 65–67, 1990.
42. A. E.-H. H. Mohamed, M. A. El-Sayed, M. E. Hegazy, S.
E. Helaly, A. M. Esmail, and N. S. Mohamed, “Chemical constituents and
biological activities of Artemisia herba-alba,” Records of Natural
Products, vol. 4, no. 1, pp. 1–25, 2010. View at Scopus
43. R. Belhattab, L. Amor, J. G. Barroso, L. G. Pedro,
and A. C. Figueiredo, “Essential oil from Artemisia
herba-albaAsso grown wild in Algeria: variability assessment and
comparison with an updated literature survey,” Arabian Journal of
Chemistry, vol. 57, no. 4, pp. 603–619, 2012.
44. T. Dob and T. Benabdelkader, “Chemical composition of
the essential oil of Artemisia herba-albaAssogrown in
Algeria,” Journal of Essential Oil Research, vol. 18, no. 6, pp. 685–690,
2006. View at Scopus
45. E. Joubert and D. de Beer, “Rooibos (Aspalathus
linearis) beyond the farm gate: from herbal tea to potential
phytopharmaceutical,” South African Journal of Botany, vol. 77, no. 4, pp.
869–886, 2011. View at Publisher · View at Google
Scholar · View at Scopus
46. F. R. Van Heerden, B.-E. Van Wyk, A. M. Viljoen, and
P. A. Steenkamp, “Phenolic variation in wild populations of Aspalathus
linearis (rooibos tea),” Biochemical Systematics and Ecology, vol.
31, no. 8, pp. 885–895, 2003. View at Publisher · View at Google
Scholar · View at Scopus
47. B. E. Van Wyk and G. H. Verdoorn, “Alkaloids of the
genera Aspalathus, Rafnia and Wiborgia (Fabaceae-Crotalarieae),” South
African Journal of Botany, vol. 55, pp. 520–522, 1989.
48. A. Kawano, H. Nakamura, S.-I. Hata, M. Minakawa, Y.
Miura, and K. Yagasaki, “Hypoglycemic effect of aspalathin, a rooibos tea
component from Aspalathus linearis, in type 2 diabetic model db/db
mice,”Phytomedicine, vol. 16, no. 5, pp. 437–443, 2009. View at Publisher · View
at Google Scholar · View at Scopus
49. J. L. Marnewick, F. H. van der Westhuizen, E.
Joubert, S. Swanevelder, P. Swart, and W. C. A. Gelderblom, “Chemoprotective
properties of rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia)
herbal and green and black (Camellia sinensis) teas against cancer promotion
induced by fumonisin B1 in rat liver,” Food and Chemical Toxicology, vol.
47, no. 1, pp. 220–229, 2009. View at Publisher · View at Google
Scholar · View at Scopus
50. S. Kreuz, E. Joubert, K.-H. Waldmann, and W. Ternes,
“Aspalathin, a flavonoid in Aspalathus linearis(rooibos), is absorbed by
pig intestine as a C-glycoside,” Nutrition Research, vol. 28, no. 10, pp.
690–701, 2008. View at Publisher · View at Google
Scholar · View at Scopus
51. A. H. Gilani, A.-U. Khan, M. N. Ghayur, S. F. Ali,
and J. W. Herzig, “Antispasmodic effects of Rooibos tea (Aspalathus linearis)
is mediated predominantly through K+-channel activation,” Basic and
Clinical Pharmacology and Toxicology, vol. 99, no. 5, pp. 365–373,
2006. View at Publisher · View at Google
Scholar · View at Scopus
52. A.-U. Khan and A. H. Gilani, “Selective
bronchodilatory effect of Rooibos tea (Aspalathus linearis) and its flavonoid,
chrysoeriol,” European Journal of Nutrition, vol. 45, no. 8, pp. 463–469,
2006. View at Publisher · View at Google
Scholar · View at Scopus
53. R. Fukasawa, A. Kanda, and S. Hara, “Anti-oxidative
effects of rooibos tea extract on autoxidation and thermal oxidation of
lipids,” Journal of Oleo Science, vol. 58, no. 6, pp. 275–283,
2009. View at Scopus
54. E. Joubert, “Effect of batch extraction conditions on
yield of soluble solids from rooibos tea,”International Journal of Food Science
and Technology, vol. 23, pp. 43–47, 1988.
55. E. Joubert, “Chemical and sensory analyses of spray-
and freeze-dried extracts of rooibos tea (Aspalathus
linearis),” International Journal of Food Science and Technology, vol. 25,
pp. 344–349, 1990.
56. E. Joubert, “Effect of batch extraction conditions on
yield of polyphenols from rooibos tea (Aspalathus
linearis),” International Journal of Food Science and Technology, vol. 25,
pp. 339–343, 1990.
57. E. Joubert, “Tristimulus colour measurement of rooibos
tea extracts as an objective colour quality parameter,” International
Journal of Food Science and Technology, vol. 30, pp. 783–792, 1995.
58. E. Joubert, M. Manley, and M. Botha, “Evaluation of
spectrophotometric methods for screening of green rooibos (Aspalathus linearis)
and green honeybush (Cyclopia genistoides) extracts for high levels of
bio-active compounds,” Phytochemical Analysis, vol. 19, no. 2, pp.
169–178, 2008. View at Publisher · View at Google
Scholar · View at Scopus
59. E. Joubert and R. Müller, “A small-scale rotary
fermentation unit for rooibos tea,” International Journal of Food Science
and Technology, vol. 32, no. 2, pp. 135–139, 1997. View at Scopus
60. E. Joubert, F. Otto, S. Grüner, and B. Weinreich,
“Reversed-phase HPLC determination of mangiferin, isomangiferin and hesperidin
in Cyclopia and the effect of harvesting date on the phenolic
composition of C. genistoides,” European Food Research and
Technology, vol. 216, no. 3, pp. 270–273, 2003. View at Scopus
61. E. Joubert, E. S. Richards, J. D. Van Der Merwe, D.
De Beer, M. Manley, and W. C. A. Gelderblom, “Effect of species variation and
processing on phenolic composition and in vitro antioxidant activity
of aqueous extracts of Cyclopia spp. (Honeybush tea),” Journal
of Agricultural and Food Chemistry, vol. 56, no. 3, pp. 954–963,
2008. View at Publisher · View at Google
Scholar · View at Scopus
62. E. Joubert and H. Schulz, “Production and quality
aspects of rooibos tea and related products. A review,”Journal of Applied
Botany and Food Quality, vol. 80, no. 2, pp. 138–144, 2006. View at Scopus
63. E. Joubert, J. D. Van der Merwe, W. C. A. Gelderblom,
and M. Manley, “Implication of CYP450 stabilization in the evaluation
of in vitro antimutagenicity of the herbal
teas, Cyclopia spp. (honeybush) and Aspalathus
linearis (rooibos) and selected polyphenols,” in Proceedings of the
Polyphenols Communications 2006: Abstracts of 23rd International Conference on
Polyphenols, pp. 505–506, Manitoba, Canada, 2006.
64. E. Joubert, P. Winterton, T. J. Britz, and D.
Ferreira, “Superoxide anion and α, α-diphenyl-β-picrylhydrazyl
radical scavenging capacity of rooibos (Aspalathus linearis) aqueous extracts,
crude phenolic fractions, tannin and flavonoids,” Food Research
International, vol. 37, no. 2, pp. 133–138, 2004. View at
Publisher · View at Google Scholar · View at Scopus
65. E. Joubert, P. Winterton, T. J. Britz, and W. C. A.
Gelderblom, “Antioxidant and pro-oxidant activities of aqueous extracts and
crude polyphenolic fractions of rooibos (Aspalathus linearis),” Journal of
Agricultural and Food Chemistry, vol. 53, no. 26, pp. 10260–10267,
2005. View at Publisher · View at Google
Scholar · View at Scopus
66. P. Mose Larsen, S. J. Fey, J. Louw, and L. Joubert,
“An anti-diabetic extract of Rooibos,” PCT ApplicationPCT/EP2008/052861
(WO, 2008/110551 A1), 2008.
67. H.-K. Na, K. S. Mossanda, J.-Y. Lee, and Y.-J. Surh,
“Inhibition of phorbol ester-induced COX-2 expression by some edible African
plants,” BioFactors, vol. 21, no. 1–4, pp. 149–153, 2004. View at
Scopus
68. F. Bruno and W. Dimpfel, “Aspalathin-like
dihydrochalcone, extracts from unfermented rooibos and process for
preparation,” PCT Patent Application PCT/EP2008/007279
(WO/2009/052895), 2009.
69. B. Brinkhaus, M. Lindner, D. Schuppan, and E. G.
Hahn, “Chemical, pharmacological and clinical profile of the East Asian medical
plant Centella asiatica,” Phytomedicine, vol. 7, no. 5, pp. 427–448,
2000. View at Scopus
70. W.-J. Kim, J. Kim, B. Veriansyah et al., “Extraction
of bioactive components from Centella asiatica using subcritical
water,” Journal of Supercritical Fluids, vol. 48, no. 3, pp. 211–216,
2009. View at Publisher ·View at Google Scholar · View at
Scopus
71. A. Shukla, A. M. Rasik, G. K. Jain, R. Shankar, D. K.
Kulshrestha, and B. N. Dhawan, “In vitro and in vivowound healing
activity of asiaticoside isolated from Centella asiatica,” Journal of
Ethnopharmacology, vol. 65, no. 1, pp. 1–11, 1999. View at
Publisher · View at Google Scholar · View at Scopus
72. J. Lee, E. Jung, Y. Kim et al., “Asiaticoside induces
human collagen I synthesis through TGFβ receptor I kinase (TβRI
kinase)-independent Smad signaling,” Planta Medica, vol. 72, no. 4, pp.
324–328, 2006.View at Publisher · View at Google
Scholar · View at Scopus
73. M. T. Thomas, R. Kurup, A. J. Johnson et al., “Elite
genotypes/chemotypes, with high contents of madecassoside and asiaticoside,
from sixty accessions of Centella asiatica of south India and the
Andaman Islands: for cultivation and utility in cosmetic and herbal drug applications,” Industrial
Crops and Products, vol. 32, no. 3, pp. 545–550, 2010. View at
Publisher · View at Google Scholar · View at Scopus
74. H. S. Long, M. A. Stander, and B. E. Van Wyk, “Notes
on the occurrence and significance of triterpenoids (asiaticoside and related
compounds) and caffeoylquinic acids in Centella species,” South African
Journal of Botany, vol. 82, pp. 53–59, 2012.
75. G. I. Stafford, M. E. Pedersen, J. van Staden, and A.
K. Jäger, “Review on plants with CNS-effects used in traditional South African
medicine against mental diseases,” Journal of Ethnopharmacology, vol. 119,
no. 3, pp. 513–537, 2008. View at Publisher · View at Google
Scholar · View at Scopus
76. A. Gurib-Fakim, M. Sewraj, J. Gueho, and E. Dulloo,
“Medicalethnobotany of some weeds of Mauritius and Rodrigues,” Journal of
Ethnopharmacology, vol. 39, no. 3, pp. 175–185, 1993. View at Scopus
77. Y. K. Gupta, M. H. Veerendra Kumar, and A. K.
Srivastava, “Effect of Centella asiatica on
pentylenetetrazole-induced kindling, cognition and oxidative stress in
rats,” Pharmacology Biochemistry and Behavior, vol. 74, no. 3, pp.
579–585, 2003. View at Publisher · View at Google
Scholar · View at Scopus
78. T. K. Chatterjee, A. Chakraborty, M. Pathak, and G.
C. Sengupta, “Effects of plant extract Centella asiatica(Linn.) on cold
restraint stress ulcer in rats,” Indian Journal of Experimental Biology,
vol. 30, no. 10, pp. 889–891, 1992. View at Scopus
79. M. Ramanathan, S. Sivakumar, P. R. Anandvijayakumar,
C. Saravanababu, and P. R. Pandian, “Neuroprotective evaluation of standardized
extract of centella asciatica in monosodium glutamate treated
rats,” Indian Journal of Experimental Biology, vol. 45, no. 5, pp.
425–431, 2007. View at Scopus
80. D. M. Pereira, J. Faria, L. Gaspar et al., “Exploiting Catharanthus
roseus roots: source of antioxidants,”Food Chemistry, vol. 121, no. 1, pp.
56–61, 2010. View at Publisher · View at Google
Scholar · View at Scopus
81. A. Gurib-Fakim, J. Gueho, and M. D.
Sewraj, Plantes Medicinales de Maurice, Editions Le Printemps, Rose Hill,
Mauritius, 1995.
82. F. Ferreres, D. M. Pereira, P. Valentão, P. B.
Andrade, R. M. Seabra, and M. Sottomayor, “New phenolic compounds and
antioxidant potential of Catharanthus roseus,” Journal of
Agricultural and Food Chemistry, vol. 56, no. 21, pp. 9967–9974,
2008. View at Publisher · View at Google
Scholar · View at Scopus
83. D. M. Pereira, F. Ferreres, J. Oliveira, P. Valentão,
P. B. Andrade, and M. Sottomayor, “Targeted metabolite analysis
of Catharanthus roseus and its biological potential,” Food and
Chemical Toxicology, vol. 47, no. 6, pp. 1349–1354, 2009. View at
Publisher · View at Google Scholar · View at Scopus
84. R. van der Heijden, D. I. Jacobs, W. Snoeijer, D.
Hallard, and R. Verpoorte, “The Catharanthus alkaloids: pharmacognosy and
biotechnology,” Current Medicinal Chemistry, vol. 11, no. 5, pp. 607–628,
2004.View at Publisher · View at Google Scholar · View at
Scopus
85. J. K. Grover, S. Yadav, and V. Vats, “Medicinal
plants of India with anti-diabetic potential,” Journal of
Ethnopharmacology, vol. 81, no. 1, pp. 81–100, 2002. View at
Publisher · View at Google Scholar · View at Scopus
86. J. Bowie, “Sketches of the botany of South
Africa,” South African Quarterly Journal, pp. 27–36, 1830.
87. J. M. Watt and M. G. Breyer-Brandwijk, Medicinal
and Poisonous Plants of Southern and Eastern Africa, E&S Livingstone,
Edinburgh, UK, 2nd edition, 1962.
88. R. Marloth, The Flora of South Africa with
Synoptical Tables of the Genera of the Higher Plants, Darter Bros & Co,
Cape Town, South Africa, 1925.
89. B. Rood, Uit Die Veldapteek, Tafelberg-Uitgewers
Bpk, Cape Town, South Africa, 1994.
90. A. Kokotkiewicz, M. Luczkiewicz, J. Pawlowska et al.,
“Isolation of xanthone and benzophenone derivatives from Cyclopia
genistoides (L.) Vent. (honeybush) and their pro-apoptotic activity on
synoviocytes from patients with rheumatoid arthritis,” Fitoterapia, vol.
90, pp. 199–208, 2013.
91. M. L. Andersen, E. H. R. Santos, M. D. L. V. Seabra,
A. A. B. Da Silva, and S. Tufik, “Evaluation of acute and chronic treatments
with Harpagophytum procumbens on Freund's adjuvant-induced arthritis
in rats,”Journal of Ethnopharmacology, vol. 91, no. 2-3, pp. 325–330,
2004. View at Publisher · View at Google
Scholar · View at Scopus
92. N. Mncwangi, W. Chen, I. Vermaak, A. M. Viljoen, and
N. Gericke, “Devil’s Claw-A review of the ethnobotany, Phytochemistry and
biological activity of Harpagophytum procumbens,” Journal of
Ethnopharmacology, vol. 143, pp. 755–771, 2012.
93. S. Chrubasik and P. R. Bradley, “Addendum to the
ESCOP monograph on Harpagophytum procumbens(multiple
letter),” Phytomedicine, vol. 11, no. 7-8, pp. 691–695, 2004. View at
Publisher · View at Google Scholar · View at Scopus
94. T. Wegener and N.-P. Lüpke, “Treatment of Patients
with Arthrosis of Hip or Knee with an Aqueous Extract of Devil's Claw
(Harpagophytum procumbens DC.),” Phytotherapy Research, vol. 17, no.
10, pp. 1165–1172, 2003. View at Publisher · View at Google
Scholar · View at Scopus
95. E. Ernst and S. Chrubasik,
“Phyto-anti-inflammatories: a systemic review of randomized, placebo-
controlled, double-blind trials,” Rheumatic Disease Clinics of North
America, vol. 26, no. 1, pp. 13–27, 2000. View at Scopus
96. P. Wenzel and T. Wegener, “Harpagophytum procumbens—a
plant antirheumatic agent,” Deutsche Apotheker Zeitung, vol. 135, no. 13,
pp. 15–28, 1995. View at Scopus
97. N. Ahmad, M. R. Hassan, H. Halder, and K. S. Bennoor,
“Effect of Momordica charantia (Karolla) extracts on fasting and
postprandial serum glucose levels in NIDDM patients,” Bangladesh Medical
Research Council Bulletin, vol. 25, no. 1, pp. 11–13, 1999. View at Scopus
98. Y. Kimura, Y. Minami, T. Tokuda, S. Nakajima, S.
Takagi, and G. Funatsu, “Primary structures of N-linked oligosaccharides of
momordin-a, a ribosome-inactivating protein from Momordica
charantiaseeds,” Agricultural and Biological Chemistry, vol. 55, no. 8,
pp. 2031–2036, 1991. View at Scopus
99. M. F. Mahomoodally, A. Gurib-Fakim, and A. H.
Subratty, “A kinetic model for in vitro intestinal uptake of
l-tyrosine and d(+)-glucose across rat everted gut sacs in the presence
of Momordica charantia, a medicinal plant used in traditional medicine
against diabetes mellitus,” Journal of Cell and Molecular Biology, vol. 3,
pp. 39–44, 2004.
100. H. Matsuda, Y. Li, T. Murakami, N. Matsumura, J.
Yamahara, and M. Yoshikawa, “Antidiabetic principles of natural medicines. III.
Structure-related inhibitory activity and action mode of oleanolic acid
glycosides on hypoglycemic activity,” Chemical and Pharmaceutical
Bulletin, vol. 46, no. 9, pp. 1399–1403, 1998. View at Scopus
101. H. Matsuura, C. Asakawa, M. Kurimoto, and J.
Mizutani, “α-Glucosidase inhibitor from the seeds of balsam pear (Momordica
charantia) and the fruit bodies of Grifola frondosa,” Bioscience,
Biotechnology and Biochemistry, vol. 66, no. 7, pp. 1576–1578, 2002. View
at Scopus
102. P. Khanna, S. C. Jain, A. Panagariya, and V. P.
Dixit, “Hypoglycemic activity of polypeptide-p from a plant
source,” Journal of Natural Products, vol. 44, no. 6, pp. 648–655,
1981. View at Scopus
103. M. S. Akhtar, M. A. Athar, and M. Yaqub, “Effect
of Momordica charantia on blood glucose level of normal and
alloxan-diabetic rabbits,” Planta Medica, vol. 42, no. 3, pp. 205–212,
1981. View at Scopus
104. D. K. Dubey, A. R. Biswas, J. S. Bapna, and S. C.
Pradhan, “Hypoglycaemic and antihyperglycaemic effects of Momordica
charantia seed extracts in albino rats,” Fitoterapia, vol. 58, no. 6,
pp. 387–390, 1987.View at Scopus
105. E. H. Karunanayake, J. Welihinda, S. R. Sirimanne,
and G. Sinnadorai, “Oral hypoglycaemic activity of some medicinal plants of Sri
Lanka,” Journal of Ethnopharmacology, vol. 11, no. 2, pp. 223–231,
1984.View at Scopus
106. A. P. Jayasooriya, M. Sakono, C. Yukizaki, M.
Kawano, K. Yamamoto, and N. Fukuda, “Effects ofMomordica charantia powder
on serum glucose levels and various lipid parameters in rats fed with
cholesterol-free and cholesterol- enriched diets,” Journal of
Ethnopharmacology, vol. 72, no. 1-2, pp. 331–336, 2000. View at
Publisher · View at Google Scholar · View at Scopus
107. S. Sarkar, M. Pranava, and R. A. Marita,
“Demonstration of the hypoglycemic action of Momordica charantia in a
validated animal model of diabetes,” Pharmacological Research, vol. 33,
no. 1, pp. 1–4, 1996. View at Publisher · View at Google
Scholar · View at Scopus
108. E. Yesilada, I. Gurbuz, and H. J. Shibata,
“Momordica charantia: an overview,” Journal of Ethnopharmacology, vol. 66,
pp. 289–293, 1999.
109. A. Raman and C. Lau, “Antidiabetic properties and
phytochemistry of Momordica charantia L.,
(Cucurbitaceae),” Phytomedicine, vol. 2, pp. 349–362, 1996.
110. B. A. Shibib, L. A. Khan, and R. Rahman,
“Hypoglycaemic activity of Coccinia indica and Momordica
charantia in diabetic rats: depression of the hepatic gluconeogenic
enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and elevation of
both liver and red-cell shunt enzyme glucose-6-phosphate dehydrogenase,” Biochemical
Journal, vol. 292, no. 1, pp. 267–270, 1993. View at Scopus
111. J. Welihinda, G. Avidson, E. Gylte, B. Hellman, and
E. Karlson, “The insulin-releasing activity of the tropical
plant Momordica charantia,” Acta Biology Medicinal Germany, vol. 41,
pp. 1229–1239, 1981.
112. J. Welihinda and E. H. Karunanayake,
“Extra-pancreatic effects of Momordica charantia in
rats,” Journal of Ethnopharmacology, vol. 17, no. 3, pp. 247–255,
1986. View at Scopus
113. H. Matsuura, C. Asakawa, M. Kurimoto, and J.
Mizutani, “α-Glucosidase inhibitor from the seeds of balsam pear (Momordica
charantia) and the fruit bodies of Grifola frondosa,” Bioscience,
Biotechnology and Biochemistry, vol. 66, no. 7, pp. 1576–1578, 2002. View
at Scopus
114. A. H. Subratty, A. Gurib-Fakim, and F. Mahomoodally,
“Bitter melon: an exotic vegetable with medicinal values,” Nutrition and
Food Science, vol. 35, no. 3, pp. 143–147, 2005. View at
Publisher ·View at Google Scholar · View at Scopus
115. M. F. Mahomoodally, A.-G. Fakim, and A. H. Subratty,
“Momordica charantia extracts inhibit uptake of monosaccharide and amino
acid across rat everted gut sacs in vitro,” Biological and
Pharmaceutical Bulletin, vol. 27, no. 2, pp. 216–218, 2004. View at
Publisher · View at Google Scholar · View at Scopus
116. M. F. Mahomoodally, A. Gurib-Fakim, and A. H.
Subratty, “Experimental evidence for in vitro fluid transport in the
presence of a traditional medicinal fruit extract across rat everted intestinal
sacs,”Fundamental and Clinical Pharmacology, vol. 19, no. 1, pp. 87–92,
2005. View at Publisher · View at Google
Scholar · View at Scopus
117. M. F. Mahomoodally, A. Gurib Fakim, and A. H.
Subratty, “Stimulatory effects of Antidesma madagascariense on D-glucose,
L-tyrosine, fluid and electrolyte transport across rat everted intestine,
comparable to insulin action in vitro,” British Journal of Biomedical
Science, vol. 63, no. 1, pp. 12–17, 2006. View at Scopus
118. A. Timmer, J. Günther, G. Rücker, E. Motschall, G.
Antes, and W. V. Kern, “Pelargonium sidoidesextract for acute respiratory tract
infections,” Cochrane Database of Systematic Reviews, no. 3, Article ID
CD006323, 2008. View at Scopus
119. T. B. Agbabiaka, R. Guo, and E. Ernst, “Pelargonium
sidoides for acute bronchitis: a systematic review and
meta-analysis,” Phytomedicine, vol. 15, no. 5, pp. 378–385,
2008. View at Publisher · View at Google
Scholar · View at Scopus
120. A. Conrad, C. Hansmann, I. Engels, F. D. Daschner,
and U. Frank, “Extract of Pelargonium sidoides(EPs) improves phagocytosis,
oxidative burst, and intracellular killing of human peripheral blood
phagocytes in vitro,” Phytomedicine, vol. 14, no. 1, pp. 46–51,
2007. View at Publisher · View at Google
Scholar · View at Scopus
121. A. Conrad, I. Jung, D. Tioua et al., “Extract
of Pelargonium sidoides (EPs) inhibits the interactions of group
A-streptococci and host epithelia in vitro,” Phytomedicine, vol. 14,
no. 1, pp. 52–59, 2007. View at Publisher · View at Google Scholar · View
at Scopus
122. A. Conrad, H. Kolodziej, and V. Schulz, “Pelargonium
sidoides-extract (EPs 7630): registration confirms efficacy and
safety,” Wiener Medizinische Wochenschrift, vol. 157, no. 13-14, pp.
331–336, 2007. View at Publisher · View at Google Scholar · View
at Scopus
123. A. Conrad and U. Frank, “Extract of Pelargonium
sidoides (EPs 7630) displays anti-infective properties by enhanced
phagocytosis and differential modulation of host-bacteria
interactions,” Planta Medica, vol. 74, no. 6, pp. 682–685, 2008. View
at Publisher · View at Google Scholar · View at Scopus
124. A. Conrad, D. Bauer, C. Hansmann, I. Engels, and U.
Frank, “Extract of Pelargonium sidoides (EPs 7630) improves
phagocytosis, oxidative burst, and intracellular killing of human peripheral
blood phagocytesin vitro,” Zeitschrift fur Phytotherapie, vol. 29, no. 1,
pp. 15–18, 2008. View at Publisher · View at Google
Scholar · View at Scopus
125. A. Conrad, D. Bauer, I. Jung et al., “Extract
of Pelargonium sidoides (EPs 7630) inhibits the interactions of group
A-streptococci and host epithelia,” Zeitschrift fur Phytotherapie, vol.
29, no. 1, pp. 19–22, 2008.View at Publisher · View at Google
Scholar · View at Scopus
126. T. Brendler and B.-E. van Wyk, “A historical,
scientific and commercial perspective on the medicinal use of Pelargonium
sidoides (Geraniaceae),” Journal of Ethnopharmacology, vol. 119, no.
3, pp. 420–433, 2008. View at Publisher · View at Google
Scholar · View at Scopus
127. O. Kayser, Phenolische Inhaltsstoffe von
Pelargonium sidoides DC. und Untersuchungen zur Wirksamkeit der Umcka-Droge
(Pelargonium sidoides DC. und Pelargonium reniforme Curt.) [Ph.D. thesis],
University of Berlin, 1997.
128. F. B. Lewu, D. S. Grierson, and A. J. Afolayan,
“Extracts from Pelargonium sidoides inhibit the growth of bacteria
and fungi,” Pharmaceutical Biology, vol. 44, no. 4, pp. 279–282,
2006. View at Publisher · View at Google
Scholar · View at Scopus
129. F. Daschner, A. Dorfmüller, I. Engels, and U. Frank,
“Untersuchungen zum antibakteriellen Wirkmechanismus von EPs7630,” Phytopharmaka
und Phytotherapie, Abstract, vol. 15, 2004.
130. N. Wittschier, G. Faller, and A. Hensel, “An extract
of Pelargonium sidoides (EPs 7630) inhibits in situ adhesion
of Helicobacter pylori to human stomach,” Phytomedicine, vol.
14, no. 4, pp. 285–288, 2007.View at Publisher · View at Google
Scholar · View at Scopus
131. W. Beil and P. Kilian, “EPs, an extract
from Pelargonium sidoides roots inhibits adherence ofHelicobacter
pylori to gastric epithelial cells,” Phytomedicine, vol. 14, no. 1,
pp. 5–8, 2007. View at Publisher · View at Google
Scholar · View at Scopus
132. N. Wittschier, C. Lengsfeld, S. Vorthems et al.,
“Large molecules as anti-adhesive compounds against pathogens,” Journal of
Pharmacy and Pharmacology, vol. 59, no. 6, pp. 777–786, 2007. View at
Publisher ·View at Google Scholar · View at Scopus
133. P. Taylor, S. Maalim, and S. Coleman, “The strange
story of umckaloabo,” Pharmaceutical Journal, vol. 275, no. 7381, pp.
790–792, 2005. View at Scopus
134. T. Gödecke, M. Kaloga, and H. Kolodziej, “A phenol
glucoside, uncommon coumarins and flavonoids from Pelargonium
sidoides DC,” Zeitschrift für Naturforschung, vol. 60, no. 6, pp.
677–682, 2005. View at Scopus
135. S. P. N. Mativandlela, J. J. M. Meyer, A. A.
Hussein, and N. Lall, “Antitubercular activity of compounds isolated
from Pelargonium sidoides,” Pharmaceutical Biology, vol. 45, no. 8,
pp. 645–650, 2007. View at Publisher · View at Google
Scholar · View at Scopus
136. O. Kayser, K. N. Masihi, and A. F. Kiderlen,
“Natural products and synthetic compounds as immunomodulators,” Expert
Review of Anti-Infective Therapy, vol. 1, no. 2, pp. 319–335, 2003. View
at Scopus
137. H. Kolodziej, “Traditionally
used Pelargonium species: chemistry and biological activity of
umckaloabo extracts and their constituents,” Current Topics in
Phytochemistry, vol. 3, pp. 77–93, 2000.
138. H. Kolodziej, “Fascinating metabolic pools
of Pelargonium sidoides and Pelargonium reniforme, traditional
and phytomedicinal sources of the herbal medicine Umckaloabo,” Phytomedicine,
vol. 14, no. 1, pp. 9–17, 2007. View at Publisher · View at
Google Scholar · View at Scopus
139. E. Koch, H. Hauer, and K. H. Stumpf, Use
of Pelargonium sidoides and Pelargonium reniforme root
extracts, World Patent WO2006002837 (European Patent EP1651244, United States
Patent 20060263448), 2006.
140. W. R. Sawadogo, M. Schumacher, M. Teiten, M. Dicato,
and M. Diederich, “Traditional West African pharmacopeia, plants and derived
compounds for cancer therapy,” Biochemical Pharmacology, vol. 84, pp.
1225–1240, 2012.
141. R. Gautam, A. Saklani, and S. M. Jachak, “Indian
medicinal plants as a source of antimycobacterial agents,” Journal of
Ethnopharmacology, vol. 110, no. 2, pp. 200–234, 2007. View at
Publisher · View at Google Scholar · View at Scopus
142. O. M. J. Kasilo and J. M. Trapsida, “Regulation of
traditional medicine in the WHO African region,” The African Health
Monitor, vol. 13, pp. 25–31, 2010.
Source:
