In Vitro Radical Scavenging Activity of the Leaf and Bark Extracts of Senna singueana (Del). Lock

Abstract

The leaves and bark of Senna singueana (Del). Lock (family: Fabaceae) are traditionally used in some parts of Ethiopia, for the treatment of a form of skin cancer locally called ‘Minshiro Nekersa\'. Total extracts and solvent fractions obtained from the leaves and bark; and fractions obtained from solid-phase extraction and TLC of the leaf extract were prepared and tested for their radical scavenging activity using DPPH (1,1- diphenyl-2-picrylhydrazyl) and deoxyribose degradation inhibition assays. The results revealed that all the samples tested possess strong DPPH radical scavenging activity and moderate deoxyribose degradation inhibitory effect. The IC50 values of the total extracts and solvent fractions ranged from 6.16 to 200.10 μg/ml in DPPH assay and 262.77 μg/ml to 1457.63 μg/ml in deoxyribose degradation inhibition assay. The TLC separated bands showed IC50 values ranging from 8.89 to 53.83 μg/ml, and 72.17 to 849.18 μg/ml, respectively, in the two assays. The positive control standard compounds ascorbic acid (for the DPPH assay)
and butylhydroxytoluene (for the deoxyribose degradation inhibition assay) showed IC50 values of 4.46 and 4.76 μg/ml, respectively. As free radicals are known to be involved in carcinogenesis, radical scavengers can short-cut free radical mediated critical steps that lead into carcinogenesis. It was thus proposed that the observed radical scavenging activity of S. singueana may contribute partly to the possible scientific basis for the traditional anticancer use of the plant.

Keywords: Senna singueana, Fabaceae, radical scavenging activity, DPPH assay, deoxyribose degradation
inhibition assay

Ethiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 77-84