Free radical scavenging and antibacterial activities of medicinal plants used in Eastern Botswana

Roots and leaves of Ozoroa paniculosa are being extensively used to treat a number of diseases including hypertension, asthma and backache [1,2,3]. Powdered root decoctions of DMT1* are used by rural dwellers in Eastern Botswana to alleviate painful menstruations, treat vaginal superficial infections, penile sores (lesions), gastrointestinal infections and diabetes mellitus related neuropathy. DMT1 root powder in petroleum jelly is known to alleviate chronic chest pains and asthma. This study is part of an ongoing project to search for health benefiting agents from natural sources. Methods: The free radical scavenging potency of the methanolic and dichloromethane extracts of DMT1 and water extract of Ozoroa paniculosa leaves were evaluated using the DPPH (Diphenypicrylhydrazyl) free radical scavenging assay. The antibacterial activities of the extracts were assessed against five Gram positive and four Gram negative typed cultures (WARD'S) of bacteria using the Agar Well Diffusion assay.

Results: At 25µg/ml the scavenging potencies of the extracts were as follows: DMT1 methanolic (89%), O. paniculosa leaves water (73%), DMT1 organic extract (56%). The scavenging powers of polar extracts of DMT1 and O. paniculosa were comparable to controls ascorbic acid and epicatechin (89 and 90%), respectively. None of the tested plant extracts showed any antibacterial activity. Conclusions: The results of this study suggest that the presence of antioxidant compounds can account for their health benefiting properties as advocated in traditional medicine.

*DMT1: Voucher specimen code for the studied plant)

Acknowledgements: Traditional Healers for supplying the plants.

References: [1] Motlhanka, D.M. et al. (2008) Planta Med. 74:928.

[2] Motlhanka, D.M. (2008) Pakistan J. Biol. Sci. 11:805–808.

[3] Motlhanka, D.M. et al. (2005)J. Pharmacol. 57:S7.