In vitro Antibacterial and Cytotoxic Activities of a Brown Antibiotic Metabolite from a Strain of Actinomycetes

摘要

The research work was conducted to investigate the in vitro antibacterial and cytotoxic activities of a antibiotic metabolite. The chloroform (CHCl₃) extract of Yeast extract-broth media (acidic) of an Actinomycetes strain yielded a brown, amorphous antibiotic pigment Di- (2-ethyl hexyl)-phthalate [AK₂]. The antibiotic and the extract exhibited significant antibacterial activity against both gram positive and gram negative organisms. The zones of inhibition produced by the test materials were found to be between 10 to 22mm. The Minimum inhibitory concentration (MIC) values of the antibiotic were determined against six strains of bacteria and were found to be between 128 to 256μg ml￣1. The cytotoxic activity of the antibiotic and CHCl₃ extract was done by brine shrimp lethality bioassay and the LC₅₀ (median lethal concentration) values were 15.8 and 12.5μg ml￣1 respectively, calculated by extrapolation from graph.