Inhibitory activity of seed extract from Picralima nitida, (Staph) on β-D-glucosidase

Abstract

The rate of hydrolysis of p- nitrophenyl β-D- glucopyranoside (PNPG) by β-D glucosidase (β-D-glucoside glucohydrolase, E.C. 2.1.21) from African giant snail (Achatina achatina) has been studied in the presence of seed extracts from Picralima nitida (Staph) Th&H.D. A at a substrate concentration range of 0.04-0.2mM there was no product (P- nitrophenol) inhibition of the enzyme. The Km and Vmax values for PNPG were calculated from Line Weaver-Burk plots and the values obtained were 0.214mM and 125-nmol/mg protein/min respectively. β-glucosidase from Achatina achatina degraded PNPG faster than, that from such as Aspergillus niger Humicola grisea and Geotricum. spp The alkaloid extracts from the mature seeds of Picralima nitida inhibited the enzyme in a competitive manner with inhibitor equilibrium constant (ki) values of 0.263, 0.157.0.125 and 0.10mg/1 for alkaloid (inhibitor) concentrations of 4,6,8 and 10mg./l respectively. The biochemical implication of this study is that since the seeds extract showed inhibition of enzyme activity, the exploitation of this potential could be of immense value in the current search for new therapeutically effective drugs with inhibitory effects against β-glucosidae which is implicated in HIV infectivity of cells.

Key Words: β-D-glucosidase, P. nitida, inhibition, HIV infectivity

Biokemistri Vol.16(2) 2004: 72-78