':t.·.7~·· .~ " BARK IN TRADITIONAL H'EALTHCARE IN KWAZULU·NATAL, SOUTH AFRICA USAGE, AUTHENTICATION AND SUSTAINABILlTY Olwen Megan Grace, a.sc. Hons. (Natal) Submitted in fulfilment of the academic requirements for the degree of Master of Science . in the Research Centre for Plant Growth and Development, School of Botany and Zoology, Faculty of Science and Agriculture, University of Natal Pietermaritzburg June 2002 .......................................................................................................................................................................................................................................................: UTrees with medicinal value are victims of their own success" - Gates 2000. ii ABSTRACT Healthcare in South Africa is polarised between western and traditional African systems of therapy. The latter is consulted by the majority of the population and therefore plays an integral role in the delivery of healthcare to South Africans. Traditional medicines are primarily plant products with long storage lives, among which the dominance of bark is typical of southern African traditional healthcare systems. Expansion of the traditional healthcare sector during the twentieth century, in response to rising consumer demands, stimulated a lucrative trade in medicinal plants that is centred in KwaZulu-Natal.(Since herbal medicines are sourced almost exclusively from indigenous vegetation, harvesting pressures exerted on the indigenous flora to meet demands for traditional medicines have rendered such resources non­ sustainable")Although trees comprise a small fraction of South African medicinal plant species, bark from them constitutes a substantial proportion of the plant products used medicinally. Trees are among the most threatened medicinal plants in South Afric~'(jU~o their limited abundance, the ecological sensitivity of the vegetation in which they occur, and destructive metl:)ods of commercial bark \ harvesting that frequently take place within protected areas. In KwaZulu-Natal, bark is ,harvested primarily " from forests that occupy an extent of only 0.1 %in the province. Conservation of economically valuable tree "'-'" species is particularly problematic since data necessary for the establishment of sustainable usage systems are absent or inaccessible. Alternatives to in situ conservation for renewable bark resources include propagation, multi-use timber systems and reintroduction of locally extinct species. To facilitate appropriate management of bark resources, there is aneed for specialist pUblications and consolidated data with which sustainable usage levels may be determined. The importance of bark in South African traditional healthcare is poorly reflected by the ethnobotanical literature. In this study, 180 bark species used in traditional healthcare in KwaZulu-Natal were inventoried from thorough literature surveys, but this number is anticipated to be a conservative reflection of actual statistics. Where trade data were recorded in the literature, they indicated intensive exploitation of bark resources in KwaZulu-Natal and throughout South Africa, but conservation and management data were lacking for 72 % of the species inventoried. A number of problems were encountered in the literature, of which vague information and the documentation of local vernacular nomenclature were the most troublesome. Despite the importance of traditional medicine, the country's political history led to the prevailing situation, where the traditional healthcare sector is largely unregulated. Coupled with increasingly limited availability of medicinal plants, the quality and appropriate use of traditional medicines is negatively affected iii by growing numbers of inadequately trained practitioners, herbalist retailers and plant gatherers. Possibilities of misidentification or purposeful adulteration of medicinal bark products therefore lead to concerns for patient safety, since dried bark is difficult or impossible to identify. Whilst bark characters are useful for field identifications, many useful diagnostic characters are lost through desiccation, and anatomy and morphology of bark are variable. Additionally, medicinal bark products used in KwaZulu-Natal, and their identification, are largely undocumented. This study focussed on eight bark species used medicinally in the province, elected by an esteemed traditional medical practitioner as having problematic identity. Monograph-type characterisation profiles were drawn up for reference specimens collected from various localities, and their medicinal bark products traded under vernacular names recorded in the literature. In the absence of standardised traditional medicines, there is a need for reliable and affordable methods for their authentication. Phytochemical bark characters identified by Thin Layer Chromatography (TLC) have proved useful in chemotaxonomic studies, and the technique is widely used for herbal drug authentication. TLC was tested here for authentication of medicinal bark products from the aforementioned study species. Three reference samples of each species were collected, and TLC-generated fingerprints compared. At the intraspecific level, TLC was useful in confirming the relationship of ethanol and hexane bark extracts, but was less meaningful in distinguishing between fingerprints of different species. Three medicina~ bark products of each study species were purchased and fingerprints compared to a reference. The technique proved useful in confirming the identity of several medicinal bark products. Authentication of medicinal bark products may be useful in toxicology cases and in the accurate documentation of their trade. This research identified a complexity of issues surrounding the use of bark in traditional healthcare in KwaZulu-Natal, and indeed South Africa. A multi-faceted approach is required to secure their sustainability. Critical, however, to factors such as effective conservation and regulation of the traditional healthcare sector, is recognition of the importance, and documentation, of traditional bark medicines. The integrity of traditional healthcare, and the future of the South African flora, hinge upon the sustainable use of medicinal products such as bark. iv PREFACE The experimental work described in this dissertation was carried out in the Research Centre for Plant Growth and Development, School of Botany and Zoology, at the University of Natal, Pietermaritzburg, from January 2001 to March 2002, under the supervision of Doctor AK Jager (presently of the Department of Medicinal Chemistry, Royal Danish School of Pharmacy, Denmark) and Doctor HDV Prendergast (Centre for Economic Botany, Royal Botanic Gardens, Kew, United Kingdom), and Professor J van Staden (Research Centre for Plant Growth and Development, University of Natal, Pietermaritzburg). This dissertation, submitted for the degree of Master of Science in the Faculty of Science and Agriculture of the University of Natal, Pietermaritzburg, represents original work by the author, except where the work of others is acknowledged. These studies have not otherwise been submitted in any form for any degree or diploma. ~. OM Grace June 2002 We certify that the above statement is correct J van Staden Supervisor ~]c/ ................................................................................~ . AK Jager Co-Supervisor 1-< .•. ,.,.. fJ~~ ..................•....................................................~ !. HDV Prendergast Co-Supervisor v ACKNOWLEDGEMENTS Sincere thanks are due to my supervisors, Professor Anna Jager, Doctor Hew Prendergast and Professor Johannes van Staden, for invaluable gUidance and discussion throughout this research project, much of which was offered through correspondence over long distances. I am grateful to the many others without whose assistance this research would not have been possible, including Mr Elliot Ndlovu, staff at the National Botanic Gardens in Pietermaritzburg, Krantzkloof and Silverglen Nature Reserves, and the Institute of Natural Resources at the University of Natal. Staff and students in the School of Botany and Zoology at the University of Natal provided many enjoyable hours of debate. My family and friends are thanked for their encouragement and support. I wish to dedicate this dissertation to my late father, Doctor HJ Grace, whose memory has inspired my academic career. vi TABLE OF CONTENTS Page ABSTRACT iii PREFACE v ACKNOWLDEGEMENTS vi TABLE OF CONTENTS ,. vii PUBLICATIONS FROM THIS RESEARCH ·.. · ·.. ix CONFERENCE CONTRIBUTIONS FROM THIS RESEARCH........................ ix LIST OF FIGURES x LIST OF PLATES xiii LIST OF TABLES ,, .. ... .. xiv Chapter 1 An introduction to South African traditional healthcare and the role of bark medicines 1 Traditional healthcare in South Africa...................................................................................... 1 Trade in traditional medicines ·.............. 6 Tree products in traditional healthcare 7 The medicinal value of bark "... 11 Objectives of the study 13 Chapter 2 Sustainability of bark resources for traditional healthcare 15 Availability of bark resources for traditional healthcare in South Africa... ... .. .... ... ... .. .... ... ... ... 15 The Forest Biome .. .... .. ....... ... ... .. .... .. .... ... ... .. .... ... .. ... .... ..... .. 15 The Savanna Biome .. .... .. ... .... ... .. .... .. .... ..... ....... .... 15 The Grassland Biome 16 The Thicket Biome :,.. ,.. ... .. ... .. .. .. .... .. 16 Historic and current