Phenolic compounds as potent free radical scavenging and enzyme inhibitory components from the leaves of guiera senegalensis

Abstract

Guiera senegalensis J.F. Gmel. (Combretaceae) is commonly used as a traditional medicine in Africa. In our previous study, the hydro-alcoholic extracts of the leaves of G. senegalensis showed potent free radical scavenging and enzyme inhibitory activities. Detailed chemical analysis of the 70% ethanol extract afforded 8 phenolic compounds including myricetin (1), myricitrin (2), quercetin (3), (-)-gallocatechin (4), 1,3,4,5-tetra-O-galloylquinic acid (5), gallic acid (6), methyl gallate (7), and ethyl gallate (8). Structures of these compounds were elucidated on the basis of NMR spectroscopic data. Among these compounds, 1,3,4,5-tetra-O-galloylquinic acid (5) (IC50= 7.21 ±0.21 µM), quercetin (3) (IC50 = 7.71 ± 0.17 µM), and myricitrin (2) (0.25 ± 0.03 µM) showed the most potent free radical scavenging, α-glucosidase inhibitory and pancreatic lipase inhibitory activities, respectively.