in vitro 5lipoxygenase and antioxidant activities of south african medicinal plants commonly used topically for skin diseases an investigation was undertaken to determine the possible mechanisms of action of medicinal plants used for dermatological pathologies a total of 14 plant species were selected from the readily available ethnobotanical literature 5lipoxygenase and dpph 22diphenyl1picrylhydrazyl assays were used to determine the antiinflammatory activity and the antioxidant activity of selected medicinal plants respectively both aqueous and methanol extracts were tested among the plants screened four species croton sylvaticus warburgia salutaris pentanisia prunelloides and melianthus comosus displayed promising 5lipoxygenase inhibitory activity with ic50 values 61 ppm a large number of plants exhibited significant antioxidant activities with ic50 values between 527 and 8336 ppm aqueous extracts of m comosus exhibited the most potent antiinflammatory and antioxidant activity