The in vitro antioxidative activity of some traditional Zulu medicinal plants.

Methanol extracts prepared separately from the roots, stems and leaves of four traditional Zulu medicinal plants (Rhoicissus digitata, R. rhomboidea, R. tomentosa and R. tridentata) were tested for their antioxidant activity. The extracts of R. rhomboidea and R. tridentata inhibited the activities of the 1, 1'-diphenyl-2-picryhydrazyl free radical, xanthine oxidase, and also prevented production of thiobarbituric acid reactive substances and free radical mediated DNA sugar damage. The extracts had a strong chelating effect on Fe(2+) ions. R. digitata and R. tomentosa extracts, however, possessed some prooxidative properties at high concentrations. In view of these results, it is apparent that the antioxidative activity of these Zulu medicinal plants plays an important role in the healing of the various diseases that they are used for. Copyright 2002 John Wiley & Sons, Ltd.