Identification, Bioactivity, and Productivity of Actinomycins from the Marine-Derived Streptomyces heliomycini

In the process of profiling the secondary metabolites of actinobacteria isolated from the Saudi coastal habitats for production of antibiotics and anti-cancer drugs, the cultures of strain WH1 that was identified as exhibited strong antibacterial activity against . By means of MS and NMR techniques, the active compounds were characterized as actinomycins X , X , and D, respectively. The research on the productivity of this strain for actinomycins revealed that the highest production of actinomycins X , X , and D was reached in the medium MII within 5% salinity and pH 8.5. In this optimized condition, the fermentation titers of actinomycins X , X , and D were 107.6 ± 4.2, 283.4 ± 75.3, and 458.0 ± 76.3 mg/L, respectively. All the three actinomycins X , X , and D showed potent cytotoxicities against the MCF-7, K562, and A549 tumor cell lines, in which actinomycin X was the most active against the three tumor cell lines with the IC values of 0.8-1.8 nM. Both actinomycins X and D showed potent antibacterial activities against and the methicillin-resistant , and and the actinomycin X was more potent.