Isolation and Characterization of Antimicrobial and Antioxidant Compounds from Actinomycetes

Abstract

Four Streptomyces spp. were isolated from the rhizosphere soil of mangrove trees (Avicennia marina) exhibited potential antimicrobial activity. They were identified by conventional and 16S rRNA gene sequencing methods as: Streptomyces atrovirens (MS5), Streptomyces labedae (MR15), Streptomyces rochei (MM23) and Streptomyces sampsonii (RR12).

The ethyl acetate extracts of the cell free broth medium of the four isolates demonstrated potent biological activities against Gram positive, Gram negative bacteria and Candida albicans. Moreover the four isolates showed radical scavenging activity percentages of 62, 78, 80, 65% at 5000, 2000, 5000, 500 µg/ml in comparison to ascorbic acid (standarad compounds) with IC50 values of 3000, 241, <50 and 78 µg/ml respectively. Streptomyces atrovirens (MS5) extract showed inhibition percentages against hepatocellular carcinoma cells (HepG-2) and colon carcinoma cells (HCT-116) cell lines with 61% and 50.6%, respectively, while Streptomyces labedae (MR15), Streptomyces rochei (MM23) and Streptomyces sampsonii (RR12) showed anticancer activity against all the tested cell lines in comparison with the control cells. LC-MS/MS analyses of the ethyl acetate of Streptomyces atrovirens (MS5) and Streptomyces labedae (MR15) revealed the presence of some compounds with known antioxidant and anticancer activities such as Gamma aminobutyric acid (GABA), Indole-3-carboxyaldehyde, linoleic acid and phenyl chromen-4-one derivative with various intensities.