Antioxidant and 15-lipoxygenase inhibitory activities of the Malian medicinal plants Diospyros abyssinica (Hiern) F. White (Ebenaceae), Lannea velutina A. Rich (Anacardiaceae) and Crossopteryx febrifuga (Afzel) Benth. (Rubiaceae)

The African flora contains numerous medicinal plants whose biological and chemical properties are incompletely known. Antioxidant and radical scavenging properties of plants are subject to intensive research. In the work described here, we have investigated the antioxidant activity of the plants Diospyros abyssinica (root bark), Lannea velutina (root bark and stem bark) and Crossopteryx febrifuga (seeds). Extracts of different polarity were assayed for radical scavenging activity, using the stable free radical diphenylpicrylhydrazyl, and for inhibition of enzymatic lipid peroxidation mediated by soybean 15-lipoxygenase. All plants investigated showed activity, but there were large differences between plants and between extracts. In general, Diospyros abyssinica and Lannea velutina were richer in antioxidants than Crossopteryx febrifuga. Lipophilic extracts were not active as radical scavengers, but did inhibit 15-lipoxygenase. Semipolar extracts (80% aqueous ethanol and methanol) of Diospyros abyssinica and Lannea velutina showed the highest activity both as radical scavengers and lipoxygenase inhibitors, and also gave the highest extract yields. These plants therefore appear to be excellent sources of antioxidants. [ABSTRACT FROM AUTHOR]