Four angucycline glycosides were previously characterized from marine-derived Streptomyces sp. OC1610.4. Further investigation of this strain cultured on different fermentation media from that used previously resulted in the isolation of two new angucycline glycosides, vineomycins E and F (1-2), and five known homologues, grincamycin L (3), vineomycinone B2 (4), fridamycin D (5), moromycin B (7), and saquayamycin B1 (8). Vineomycin F (2) contains an unusual ring-cleavage deoxy sugar. All the angucycline glycosides isolated from Streptomyces sp. OC1610.4 were evaluated for their cytotoxic activity against breast cancer cells MCF-7, MDA-MB-231, and BT-474. Moromycin B (7), saquayamycin B1 (8), and saquayamycin B (9) displayed potent anti-proliferation against the tested cell lines, with IC50 values ranging from 0.16 to 0.67 μM. Saquayamycin B (9) inhibited the migration and invasion of MDA-MB-231 cells in a dose-dependent manner, as detected by Transwell and wound-healing assays.
Keywords: MDA-MB-231; Streptomyces; angucycline; breast cancer cell; cytotoxicity; migration; saquayamycin; vineomycin.