Evaluation of antioxidant, antimicrobial and antitumor compounds production potential of Streptomyces antioxidans PU-12M

Abstract

Streptomycetes are prolific producers of biologically active secondary metabolites with great structural and functional diversity, which are widely used as pharmaceutical products. The strain Streptomyces sp. PU-12M was investigated for its potential to produce antioxidant, antimicrobial and antitumor compounds. For this purpose, the laboratory scale fermentation (10 liters working volume) of the strain was performed followed by cell separation, solvent extraction and partial purification of biologically active compounds by silica gel fractionation column chromatography and preparative TLC. The antioxidant activity was determined by DPPH radical scavenging assay, antimicrobial activity by agar well diffusion assay while in vitro antitumor activity was determined by MTT and SRB assays. Altogether 24 partially purified compounds or fractions were retrieved from the extract of strain Streptomyces Sp. PU-12M and were subsequently investigated for biological activity. Among them, three fractions were found to have potent antioxidant activity. The crude extracts and the partially purified fractions were found to have promising antimicrobial activity with MIC up to 3.2mg/ml. The partially purified fractions exhibited varied cytotoxicity ranging from 40% to 100% mortality against brine shrimp (Artemia salina) larvae and 22% to 67% growth inhibition of HCT 116 colorectal cancer cell lines. The study reveals that Streptomyces antioxidans PU-12M is a proliferent producer of bioactive secondary metabolites and can be exploited further to produce the commercially useful bioactive molecules.