Abstract

Erythropheleum suaveolens stem bark saponins fractions were investigated for antioxidant and antibacterial activities. In vitro systems such as, 1, 1- diphenyl-2-picrylhydrazyl (DPPH) radical, reductive potential and inhibition of lipid peroxidation were carried out to determine the antioxidant activities. The antimicrobial activity was determined using the hole-in-plate agar diffusion technique and the minimum inhibitory concentration (MIC) of each fraction was determined using the agar dilution method. All the fractions scavenged DPPH radicals but not comparable with ascorbic acid. These fractions also inhibited lipid peroxidation induced with highest percentage inhibition exhibited by 70:30 fraction which compare favourably with tannic acid. The reducing potential decreased with increasing concentration for all the fractions. The result of antibacterial studies revealed that 70:30 fraction inhibited the tested bacteria to a greater extent than the other fractions while the determination of the MIC of each fraction against the organisms showed that 70:30 fraction possessed a broader spectrum of activity against gram positive cocci of medical importance and also inhibited all the gram negative organisms tested. The study indicates saponin fractions of E. suaveolens stem bark to be potential candidates as antioxidant and antimicrobial agents with the 70:30 saponin fractions being the most promising and that these two activities augment each other.

Key words: Erythropheleum suaveolens, saponins, 1, 1- diphenyl-2-picrylhydrazyl (DPPH), lipid peroxidation, reductive potential and antimicrobial.