Investigation on pharmacological activities of secondary metabolite extracted from a mangrove associated actinobacterium Streptomyces olivaceus (MSU3)

The present study was undertaken to evaluate pharmacological activities of secondary metabolite of Streptomyces olivaceus (MSU3) isolated from the sediment sample of a mangrove ecosystem. The isolated strain was screened for its preliminary antagonistic property against various clinical pathogens and its secondary metabolite was extracted by using ethyl acetate. The 30 µl concentration of the crude extract of the isolate expressed the maximum zone of inhibition of 27±2.44 mm against the bacterial pathogen Streptococcus mutant with the MIC and MBC values of 0.625 and ≤5 µg/ml concentrations, respectively. Further different concentrations of extract were tested for in-vitro antioxidant, antiinflammatory and in-vivo cytotoxicity studies. It expressed the maximum percentage of in-vitro total antioxidant activity of 87%, DPPH scavenging activity of 62.06%, reducing power effect of 32.51%, hydroxyl radical scavenging activity of 47.99% and nitric oxide activity of 33.20% at 100 µg/ml concentration respectively. Further the extract exhibited 96.63% of inhibition of in-vitro antiinflammatory activity, 49.60% of total hemolytic activity and also has 42.11% of total phenolic content at respective concentration of 500 µg/ml. The cytotoxic effect of the crude extract was analyzed by MTT assay on MCF-7 and HT-29 cell lines and the cell viabilities were observed as 24.00% and 39.17% at 250 µg/ml concentration with the respective IC50 values of 88.26 and 104.81 µg/ml. From the results, it is evident that the ethyl acetate crude extract of S. olivaceus (MSU3) has potent antimicrobial, antioxidant, antiinflammatory and cytotoxic activity and suggested that the isolated strain could be a candidate for the nature resource of pharmaceutical.