Editorial commentGlobal phytochemistry: indigenous medicinal chemistry on track in southern Africa
Introduction
Southern Africa is one of the richest centers of plant diversity in the world. The flora is not only extremely rich and diverse (about 24 300 higher plant taxa) (Arnold and de Wet 1993), but is also largely endemic in character.
The Cape Floristic Region with nearly 6000 endemic species is one of the world's richest floral regions. Southern Africa has a great range of climatic zones (sub-tropical to Mediterranean) and habitat types (Afro-alpine grasslands to coastal deserts), and a correspondingly diverse and well-adapted flora. The indigenous people of southern Africa have a long history of traditional plant usage for medicinal purposes, with ca. 4000 taxa so employed. The trade in medicinal plants is an important part of the regional economy with over 700 plant species being reported as traded (Mander, 1998). In South Africa it is estimated that there are 27 million indigenous medicine consumers. Accordingly demand has exceeded sustainable supply with several species such as Warburgia salutaris (Bertol. F), Chiov. (Pepperbark Tree) and Siphonochilus aethiopicus (Schweinf.) B.L. Burtt (Wild Ginger) becoming locally extinct, especially outside of protected areas (Mander, 1998).
The value of trade in ethnomedicinal plants in KwaZulu-Natal alone was estimated to be worth R60 million ($10 million) in 1998. Most households spend between 4 and 8% of their annual income on traditional medicinal services. In addition, in KwaZulu-Natal between 20 000 and 30 000 people derive an income from trading indigenous plants. Most of these are rural black women, the most marginalized group in South African society. Mander (1998) estimated that in 1998 the trade in medicinal plants in South Africa was nearly 20 000 t with a total value of $110 million. Apart from traditional plant usage, plants such as Aspalathus linearis (Burm. F) Dahlg. (Rooibos), Harpagophytum procumbens (Burch.) DC. Ex Meissn. (Devil's Claw), Hypoxis hemerocallidea Fisch.& C.A. Mey (African potato) and Cape aloe (Aloe ferox mainly) are exported to the East and Europe.
In this review the attempts to unravel the complex chemistry of the flora of southern Africa will be described. The task was carried out by natural products chemists from all over the world and spans the period 1900–2003. During this period decisive political and other events took place in the region, including the Anglo-Boer War, the second World War, and the arrival of Democratic Government in South Africa. All of these influenced the progress of Science in the subcontinent.
Section snippets
Gold and stock diseases
By 1902, the bitter Anglo-Boer War (1899–1902) in which Brit fought against Afrikaner on the southern tip of Africa, had ended. In 1910, the Union of South Africa was founded with four constituent provinces: Cape of Good Hope, Transvaal, Natal and Orange Free State. The discovery of rich gold deposits in 1884 on the Witwatersrand brought an influx of foreigners to the country, and, with it, a new and vigorous industry. However, in rural South Africa farming remained as an important mainstay of
A changing world and a change in the face of chemistry
The Second World War had ended in 1945 and this in itself changed the face of South and southern Africa. Science research received a tremendous boost through the establishment in 1945 of the Council for Scientific and Industrial Research (CSIR), based in Pretoria. Its founding president was Sir Basil Schonland who later became Director of the Atomic Energy Research Establishment in Harwell.
Further changes which had a profound influence on Natural Products research were:
- 1.
The emergence of natural
Into a new century and start of democratic government
Up to 1984 research scientists in South Africa were funded from government funds via the Council for Scientific and Industrial Research (CSIR). From June 1984 this funding was channeled through a new body, the Foundation for Research Development (FRD), still within the CSIR ambit. In 1990, the FRD became an independent State body, no longer attached to the CSIR and with its own administrative headquarters on the periphery of the CSIR complex in Pretoria. Its first president was Dr. Reinhard
The KwaZulu-Natal groups
During this period natural products chemistry research has been a dominant theme in the KwaZulu-Natal area. Professor Siegfried Drewes of the University of Natal (Pietermaritzburg campus) has made significant contributions to the study of the phytochemistry of medicinal plants of KwaZulu-Natal. His involvement in Natural Products Research dates back to the 1960s. More recent work includes the isolation and synthesis of rooperol, (9), the anti-cancer constituent found in Hypoxis hemerocallidea
Rhodes University
The marine natural products research group in the Chemistry Department at Rhodes University has, over the last decade, investigated the bioactive natural products produced by more than 500 marine invertebrate organisms randomly collected by SCUBA off the south eastern coast of Southern Africa. Many of the endemic marine invertebrate species inhabiting the sub-tidal reefs off southern Africa are prolific producers of novel bioactive secondary metabolites. The Rhodes University research group has
Other researchers investigating traditionally used plants
In addition to the natural products chemists involved in this area, several botanists and pharmacologists have become involved in natural products research A leading example is Professor Johannes van Staden of the University of Natal (Pietermaritzburg), whose interest lies in the screening of plants for anti-inflammatory and anti-microbial properties (Rabe et al., 2002, Sparg et al., 2002, Taylor and van Staden, 2002).
Professor Marion Meyer's (University of Pretoria) research involves
Commercial products
Several plant extracts derived from South African medicinal plants are available commercially:
- 1.
“Moducare”, originally from Hypoxis, to boost the immune system and cure arthritis.
- 2.
Sutherlandia frutescens whole dried plant material now on the market to combat muscle wasting and general debility in HIV patients. (Produced by Phyto Nova in Cape Town).
- 3.
Hoodia currorii (Fig. 3)—The Khoi/San plant developed by CSIR as an appetite suppressant as early as 1967 with Professor Fanie van Heerden being one of
Conclusion
The field of natural product chemistry is an extremely active one in Southern Africa. The recent award of a substantial National Research Foundation Innovation Fund grant to facilitate drug discovery by bringing together some of the country's leading chemists, ethnobotanists, pharmacologists and medical researchers bodes well for the future.
Dulcie Mulholland obtained her PhD degree in 1980 from the University of Natal in Durban working with Professor David Taylor on the limonoids from Trichilia dregeana. She returned to the University to take up an academic position in 1991 and continued her work on the chemistry of the Meliaceae and related families. She heads the Natural Products Research Group at the University, is Professor of Organic Chemistry and is Head of the School of Pure and Applied Chemistry. Her research interests
References (95)
- et al.
Diterpenes from the timber of 20 Erythroxylum species
Phytochem.
(1993) - et al.
New non contiguous polypropionates from marine molluscsa comment on their natural product status
Tetrahedron
(2000) - et al.
A dinitrogenous alkaloid from Cyrtanthus obliquus
Phytochemistry
(2002) - et al.
Bioactive alkaloids from Brunsvigia radulosa
Phytochem.
(2000) - et al.
The occurrence of actractyloside in Callilepis laureola
Phytochem.
(1977) - et al.
Bulb alkaloids from the reputedly psychoactive Brunsvigia radulosa (Amaryllidaceae)
South African Journal of Botany
(2002) - et al.
Isolation of hypoxoside from Hypoxis rooperi and synthesis of (E)-1,5-bis(3′,4′-dimethoxyphenyl)pent-4-en-1-yne
Phytochem.
(1984) - et al.
Pyrano-isoflavones with erectile-dysfunction activity from Eriosema kraussianum
Phytochem.
(2002) The isolation and structure of cyclopiazonic acid, a toxic metabolite of Penicillium cyclopium
Tetrahedron
(1968)- et al.
Sesquiterpene hydroquinones from the South African soft coral Alcyonium fauri
Tetrahedron Letters
(1995)
Inhibition of drug-sensitive and resistant strains of Mycobacterium tuberculosis and other bacterial species by diospyrin, isolated from Euclea natalensis
J. Ethnopharmacology
A drimane sesquiterpenoid lactone from Warburgia salutaris
Phytochem.
Antibacterial activity of South African Helichrysum species
South African Journal of Botany
In vitro inhibition of drug-resistant and drug-sensitive strains of Mycobacterium tuberculosis by Helichrysum caespititium
South African Journal of Botany
Limonoids from the seed of the Natal Mahogany, Trichilia dregeana
Phytochem.
Limonoid derivatives from Cedrelopsis grevei
Tetrahedron
Delevoyin C, a tetranortriterpenoid from Entandrophragma delevoyi
Phytochem.
Limonoid derivatives from Astrotrichilia voamatata
Phytochem
Sensitivity gain in a progressive saturation selective population inversion NMR Experiment
J. Magn. Res.
Bufadienolides from Drimia robusta and Urginea altissima
Phytochem.
Isolation and identification of antibacterial compounds from Vernonia colorata leaves
J. Ethnopharmacol.
Pharmacological and phytochemical screening of two Hyacinthaceae species: Scilla natalensis and Ledebouria ovatifolia
Journal of Ethnopharmacology
Ekebergin, a limonoid extractive from Ekebergia capensis
Phytochem.
Aloerisin E and F, two chromone derivatives from Aloe peglerae
Phytochem.
The essential oil composition of the roots and rhizomes of Siphonochilus aethiopicus
South African Journal of Botany
Dinklagins A, B and C: three prenylated flavonoids from the twigs of Dorstenia dinklagei
Phytochem.
Plants of Southern Africa: Names and Distribution. Memoirs of the Botanical Survey of South Africa No 62
The constitution of geigerin
J. Chem. Soc.
Constitution of wing gland and abdominal hairpencil secretions of the male African sugar cane borer, Eldana saccharina
J. Chem. Ecol.
Composition and antimalarial activity of the essential oil of Tetradenia riparia
Planta Medica
Cytotoxic and antimalarial alkaloids from Brunsvigia littoralis
Planta Medica
The Absolute Stereochemistry of Ibhayinol from a South African Sea Hare
Journal of Natural Products
Ragwort poisoning in cattle and cirrhosis of the liver in horses
Vet. Record
Senecio alkaloids X. The structures of scleranecic acid and sceleratinic acids
J.S. Afr. Chem. Inst.
Ocobullenone: a neolignan from Ocotea bullata
Phytochem.
Stereochemistry and biogenesis of Mopanols and Peltogynols from Colophospermum mopane
J. Chem. Soc.(C)
Extraction of antibacterial compounds from Combretum microphyllum
South African Journal of Botany
Bitter principles from the Cucurbitaceae
J. S. Afr. Chem. Inst.
Isolation and characterization of steroidal sapogenins from Tribulus terrestris
J. S. Afr. Chem. Inst.
Caespitin, a new phloroglucinol derivative with anti-microbial properties from Helichrysum caespititium
S. Afr. J. Chem.
Chemistry of lichen constituents III. Haemathamnolic acid: a new β-orcinol depside from Petrusaria rhodesiaca
J. Chem. Soc.
Vermeersiekte or vomit sickness of sheep
Agric. Jour. C. of Good Hope
Effect of dietary plant and animal protein intake on sperm quality in monkeys
Arch. Androl.
Effect of extraction time and additional heating on the anti-oxidant activity of rooibos (Aspalathus linearis) tea extracts
J. of Agric. and Food Chem.
Phenolic compounds from Cyclopia intermedia
J. of Agric and Food Chem.
Notes on the active principle of some South African Plants
Chem. News
Cited by (29)
Phytochemical Profiling of Commercially Important South African Plants
2021, Phytochemical Profiling of Commercially Important South African PlantsCroton megalobotrys Müll Arg. and Vitex doniana (Sweet): Traditional medicinal plants in a three-step treatment regimen that inhibit in vitro replication of HIV-1
2016, Journal of EthnopharmacologyCitation Excerpt :In February and October 2014, two additional batches of plant material consisting of V. doniana roots and C. megalobotrys bark of mature trees were collected with the help of the traditional healer S. Simonambango (a former long-term apprentice of A. Namushe) at two different sites in the Kazungula District covering the Zambia/Botswana border region and around Maun in North-Western Botswana (Fig. 1). Additional information about traditional medicinal plants used for HIV/AIDS treatment and management were obtained via literature search (Artemisia afra; Mulholland and Drewes, 2004 and Croton gratissimus; Mthethwa et al., 2014) and species were collected in Gaborone. Furthermore, two traditional healers from the village of Mmankgodi in Southern Botswana, Kweneng District (Fig. 1) contributed knowledge about Jatropha erythropoda and Ozoroa paniculosa during an ethnosurvey undertaken between 2008 and 2010 (Andrae-Marobela et al., 2010).
Warburgia: A comprehensive review of the botany, traditional uses and phytochemistry
2015, Journal of EthnopharmacologyCitation Excerpt :On one hand, this has created employment opportunities in the informal sector, but on the other, this has led to the endangerment or even extinction of many plant species. In South Africa alone, it was estimated ten years ago that as many as 27 million people consume indigenous medicines (Mulholland and Drewes, 2004). Even though, W. salutaris does not occur naturally in the Western Cape Province (South Africa), it is used traditionally by the Rastafarian bush doctors in the area as an emetic, in cases of respiratory illnesses and to increase blood circulation (Aston-Philander, 2011).
Ethnopharmacology in overdrive: The remarkable anti-HIV activity of Artemisia annua
2012, Journal of EthnopharmacologyCitation Excerpt :This was done in order to determine if ART is responsible for the observed anti-HIV activity, or if a combination of ART and other components can explain the observed activity (synergism). We could not find any literature reports on any anti-HIV activity ascribed to Artemisia afra (Liu et al., 2009) except one report where HIV infected patients were given Artemisia afra together with standard HIV treatment in order to boost their immune systems (Mulholland and Drewes, 2004). For a further control plant we included the common tea and unrelated Aspalathus linearis (N.L. Burm.)
Uptake and translocation of heavy metals by medicinal plants growing around a waste dump site in Pretoria, South Africa
2012, South African Journal of BotanyCitation Excerpt :Moreover, a greater number of people in South Africa still rely on the use of herbal medicine. It was estimated by Mulholland and Drewes (2004) that significantly higher number of patients in South Africa consult traditional healers for potentially life threatening conditions. The plants used for this study were D. stramonium and A. spinosus.
Eucomis zambesiaca baker: Factors affecting in vitro bulblet induction
2010, South African Journal of Botany
Dulcie Mulholland obtained her PhD degree in 1980 from the University of Natal in Durban working with Professor David Taylor on the limonoids from Trichilia dregeana. She returned to the University to take up an academic position in 1991 and continued her work on the chemistry of the Meliaceae and related families. She heads the Natural Products Research Group at the University, is Professor of Organic Chemistry and is Head of the School of Pure and Applied Chemistry. Her research interests have expanded to include the chemistry of the Rutaceae, Amaryllidaceae and Hyacinthaceae families.
Siegfried Drewes obtained his PhD from Rhodes University and a DSc from the University of Natal. His interest in natural products was kindled during his PhD years working with Professor David Roux on the tannins of Acacia mearnsii at the Leather Industries' Research Institute in Grahamstown. He joined the University of Natal in 1969, had a brief sojourn into protein chemistry (insulin derivatives) with Professor Donald Sutton and then reverted to natural products again, specifically the chemistry of muthi plants (indigenous plants used by the traditional healers). His work in this area culminated in the award of an “A” rating by the Foundation for Research Development. In 1995 he retired as Head of the Department of Chemistry, but has stayed on in the Department as Honorary Research Associate. He rates among his most memorable achievements the isolation of ocobullenone from Ocotea bullata, rooperol from Hypoxis hemerocallidea, and the kraussianones from Eriosema kraussianum.