Actinobacteria from soil as potential free radical scavengers

ABSTRACT

Aims: Actinobacteria, the Gram positive bacteria are known to produce about 10,000 bioactive secondary metabolites. Among them, 80% of the metabolites are produced by Streptomyces like antibiotics, anticancer, antimicrobial, antioxidant, enzymes, etc. But most of the Streptomyces species are still to be explored for the different bioactivities. Hence, the present work is designed to evaluate the antioxidant activities of the secondary metabolites produced by the strains of Streptomyces designated as OS-6 and TES-25 on the free radicals generated in the different in vitro assays. Methodology and results: The antioxidant activity of ethyl acetate and chloroform extracts of OS-6 and TES-25 was analyzed by performing different antioxidant assays viz. molybdate ion reduction assay, DPPH radical scavenging assay, ABTS radical cation decolourization assay, reducing power assay, deoxyribose degradation assay, lipid peroxidation assay, superoxide anion scavenging assay and DNA nicking assay. The total phenolic content was also determined. The findings showed that maximum hydrogen or electron donating and hydroxyl radical scavenging activities were exhibited by OS-6 ethyl acetate extract in all the assays. Conclusion, significance and impact of study The potent antioxidant activity may be due to the presence of different polyphenolic compounds as depicted from the total phenolic content of the extracts. Further study includes the isolation of compounds responsible for the antioxidant activity.