Prashith Kekuda TR, Shobha KS , Onkarappa R , Goutham SA , Raghavendra HL
The present study was undertaken to screen biological activities namely antimicrobial, insecticidal, pancreatic lipase inhibitory and cytotoxic potential of crude extract of a Streptomyces species isolated from soil of Agumbe, Karnataka, India. Primary and Secondary screening for antimicrobial activity was determined by Cross streak method and Agar well diffusion method respectively. Insecticidal efficacy of extract was tested against 3rd instar larvae of Aedes aegypti. Pancreatic lipase inhibitory activity was determined against chicken pancreatic lipase. The brine shrimp lethality test was conducted to determine cytotoxic nature of crude extract. The actinomycete isolate was identified as a species of the genus Streptomyces on the basis of microscopic, cultural and biochemical characteristics. In both primary and secondary screening, Gram positive bacteria were found most sensitive. Candida albicans has shown high sensitivity when compared to Cryptococcus neoformans. The mortality of the 3rd instar larvae of A. aegypti was found to be concentration dependent and the mortality was 100% at extract concentration 1.5mg/ml and higher. The inhibition of lipase was found to be dose dependent and an inhibition of over 50% was observed at extract concentration 50mg/ml. In cytotoxic assay, the degree of lethality of extract was directly proportional to the concentration. The LC50 of extract was found to be 21.95μg/ml and hence the extract is toxic. The soils of Western ghats are rich sources for microorganisms with potent biological activities and screening programs are to be conducted to reveal the presence of pharmacologically active actinomycete isolates. Further studies are needed to be carried out to isolate and characterize the active principles present in the crude extract and determine their biological activity.
