An investigation into the potential mutagenicity of South African traditional medicinal plants

Nair, Amatheni

An investigation into the potential mutagenicity of South African traditional medicinal plants

Master Thesis

2010

Publisher

University of Cape Town

Department

Department of Medicine

Faculty

Faculty of Health Sciences

Abstract

The potential mutagenicity and clastogenicity (ability to cause chromosomal damage) of five South African traditional medicinal plants: Acokanthera oppositifolia (Lam.); Pelargonium sp. cf. inquinans ( L.) L Herit; Pteridium aquilinum subsp aquilinum; Rumex lanceolatus Thunb. and Zantedeschia aethiopica (L.) Sg, were investigated using two in vitro tests in both a bacterial and a mammalian cell system. The Salmonella reverse mutation assay and chromosomal aberration test, two frequently used and accepted pharmacological bioassays, were selected for the investigation. The rat liver extract (S9), containing CYP P450 and other liver enzymes, was added to the in vitro cell system to detect pro-mutagens that require metabolic activation in order to exert mutagenicity or clastogenicity - directly acting mutagens do not require metabolic activation. A significant mutagenic potential (p 0.01) was evident with the Salmonella reverse mutation assay for three of the aqueous plant extracts: (i) R. lanceolatus (in strains TA97a, TA98, TA100 and TA102) with and without metabolic activation (S9), (ii) P. aquilinum in TA100 with S9 and in TA102 without S9 and (iii) Pelargonium (in TA102) without S9. Furthermore, R. lanceolatus and P. aquilinum were clastogenic in the chromosomal aberration test but this effect was reduced with S9. Z. aethiopica demonstrated clastogenicity, which was reduced with S9, but the extract was not mutagenic. Since the chromosomal aberration test is dependent on cells entering the cell cycle (Go-G1, S and G2-M) and chromosome visibility with light microscopy only occurs at metaphase, the clastogenicity of A. oppositifolia and Pelargonium could not be detected because these extracts inhibited mitosis (M). A DNA analysis of cultures treated with A. oppositifolia and Pelargonium by Flow Activated Cell Sorting (FACS) indicated a blockage in the Go/G1 phase of the cell cycle. The in vitro mutagenicity and clastogenicity tests served as a preliminary investigation into the safety of five traditional plants. In addition to mutagenicity testing, it is suggested that further scientific evaluation, validation, standardisation and regulation of South African traditional medicine is essential in order to prevent the adverse acute and chronic effects of plant ingestion. iii

Keywords

Medicine

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