Abstract

Many microorganisms are responsible for causing serious diseases of bacterial origin. Development of drug resistance in animal and human pathogens against commonly used antibiotics has necessitated a search for new antimicrobial substances from other sources including plants. The present study reports on the antimicrobial and brine shrimp lethality of Piliostigma thonningii leaves collected from two geographical regions, Kenya and Malawi. Both aqueous as well as organic extracts from leaves of P. thonningii were screened for antibacterial activity against bacteria of human and veterinary importance using agar well diffusion and evaluated for acute toxicity using brine shrimp bioassay. Except for chloroform extract of P. thonningii from Malawi, all of the plant extracts demonstrated remarkable antibacterial activity against the five test bacteria at concentrations tested (250 µg/ml) in agar well diffusion method. In brine shrimp bioassay, all the crude extracts from Kenya and Malawi exhibited varying degrees of toxicity against Artemia salina larvae. Nevertheless, further evaluation of thein vivo toxicity and in vivo antibacterial activity of the crude plant extracts should be carried out.

Key words: Piliostigma Thonningii, brine shrimp bioassay, antibacterial activity, crude plant extract, Kenya, Malawi.