Mutation Research 581 (2005) 35–42 Antioxidant and genotoxic properties of South African herbal extracts Vanessa Steenkamp a,∗ , Heidi Grimmer b , Mpho Semano c , Mary Gulumian c,d a Department of Pharmacology, School of Medicine, Faculty of Health Sciences, University of Pretoria, P.O. Box 2034, Pretoria 0001, South Africa b South African Breweries, P.O. Box 782178, Sandton 2146, South Africa c National Institute for Occupational Health, P.O. Box 4788, Johannesburg, South Africa d Department of Haematology and Molecular Medicine, Faculty of Health Sciences, University of the Witwatersrand, South Africa Received 28 June 2004; received in revised form 28 September 2004; accepted 28 October 2004 Available online 23 December 2004 Abstract This study investigated the antioxidant and genotoxic properties of 13 South African herbal extracts. Results from the single- cell gel electrophoresis (Comet) assay indicated that there were profound differences between the plant extracts in their ability to produce DNA damage, which varied from highly genotoxic to protective. Similarly, water and methanol extracts of all the herbal preparations showed variable potencies in scavenging hydroxyl radicals, as measured by means of electron spin resonance spectrometery (ESR) with the spin trap -phenyl-N-tert-butylnitrone (PBN). In general, methanol extracts were better scavengers of hydroxyl radicals than the corresponding water extracts. This was also true of the ability of these extracts to inhibit membrane lipid peroxidation, assessed with diphenyl-1-pyrenylphosphine (DPPP). However, neither methanol nor water extracts had the ability to protect against DNA damage. The results show that further research on South African traditional herbal extracts is imperative to gain understanding of the mechanisms involved in their pharmacological effects. The tests implemented in the present investigation are recommended for screening other herbal extracts. © 2004 Elsevier B.V. All rights reserved. Keywords: DNA damage; Comet assay; Lipid peroxidation; Hydroxyl radical; Traditional herbal remedies; South Africa ∗ Corresponding author. Tel.: +27 12 3192547; fax: +27 12 3211081. E-mail address: vsteen@med.up.ac.za (V. Steenkamp). 1. Introduction The use of traditional herbal remedies as alterna- tive medicine plays a significant role in South Africa, since it forms part of the culture and beliefs of the in- digenous population and also features significantly in 1383-5718/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mrgentox.2004.10.009