Exometabolites of streptomycetes isolated from the Odesa bay exhibit a toxic effect against human cancer cell lines

The aim of the work was to determine the cytotoxic activity of marine actinobacteria exometabolites on the human larynx adenocarcinoma Hep-2 and rhabdomyosarcoma RD cell lines. Exometabolites of 6 strains of Streptomyces sp. were extracted with ethyl acetate and their composition was determined with UltiMate™ 3000 BioRS UPLC System coupled to mass spectrometer. Cytotoxic activity of exometabolites against cancer cells was determined after 24 hours of incubation by microscopic examination of cell morphological changes and the degree of cell monolayer degeneration. Exometabolites from Streptomyces sp. Myt7b strain showed the highest cytotoxic activity and at concentration of 500.0 μg/ml caused up to 90.0% death of RD and Hep-2 cells. The presence of 53 identified compounds with potential cytotoxic activity, including enterocin, 6-prenyltryptophol, medelamine A and turbinaric acid was detected in Streptomyces sp. Myt7b exometabolome. It is concluded that this strain is a promising producer of compounds with anticancer activity. Keywords: cytotoxic activity, exometabolites, marine streptomycetes, RD and Hep-2 cancer cells