Monacycliones G–K and <i>ent</i>-Gephyromycin A, Angucycline Derivatives from the Marine-Derived <i>Streptomyces</i> sp. HDN15129
Yimin Chang, Li Xing, Chunxiao Sun, Shuang Liang, Tao Liu, Xiaomin Zhang, Tianjiao Zhu, Blaine A. Pfeifer, Qian Che, Guojian Zhang, Dehai Li
Abstract
Six new angucycline derivatives, named monacycliones G–K (1–5) and ent-gephyromycin A (6), as well as three known ones (7–9) were discovered from the marine sediment-derived actinomycete Streptomyces sp. HDN15129 guided by Global Natural Products Social (GNPS) molecular networking. Structures including absolute configurations were elucidated by extensive NMR, MS, and ECD analyses. Among them, monacyclione G (1) possesses a unique scaffold featuring a xanthone core linked to the aminodeoxysugar ossamine, and monacycliones H–J (2–4) are rare examples of natural angucyclines with an S-methyl group. Monacycliones I and J (3 and 4) showed cytotoxic activity against multiple human cancer cell lines, with IC50 values ranging from 3.5 to 10 μM.