Streptomyces puniceus strain AS13., Production, characterization and evaluation of bioactive metabolites: A new face of dinactin as an antitumor antibiotic.

A highly active actinobacterial strain isolated from untapped areas of Northwestern Himalayas and characterised as Streptomyces puniceus strain AS13 by 16S rRNA gene sequencing was selected for production of bioactive metabolites. The bioassay-guided fractionation of microbial cultured ethyl acetate extract of the strain, led to isolation of macrotetrolide compound 1 (Dinactin) and compound 2 (1-(2,4-dihydroxy-6-methylphenyl)-ethanone). Structures of the isolated compounds were elucidated interpretation of NMR and other spectroscopic data including HR-ESI-MS, FT-IR. These compounds are reported for first time from Streptomyces Puniceus. Compound 1 exhibited strong anti-microbial activity against all tested bacterial pathogens including Mycobacterium tuberculosis. The MIC values of compound 1 against Gram negative and Gram positive bacterial pathogens ranged between 0.019 - 0.156μgml-1 and 1μgml-1 against Mycobacterium tuberculosis H37Rv. Dinactin exhibited marked anti-tumor potential with IC50 of 1.1- 9.7μM in various human cancerous cell lines and showed least cytotoxicity (IC50 ∼80μM) in normal cells (HEK-293). Dinactin inhabited cellular proliferation in cancer cells, reduced their clonogenic survival as validated by clonogenic assay and also inhabited cell migration and invasion characteristics in colon cancer (HCT-116) cells. Our results expressed the antimicrobial potential of dinactin and also spotted its prospective as an antitumor antibiotic.