20 December 2019
Cangumycins A−F ( 1– 6), six new angucyclinone analogues, together with two known ones ( 7 and 8), were isolated from the fermentation broth of a soil-derived Streptomyces sp. KIB-M10. Structures of these compounds were elucidated via a joint use of spectroscopic analyses and single-crystal X-ray diffractions. Among them, cangumycins E ( 5) and F ( 6) share a C-ring cleaved backbone, and cangumycins B ( 2) and E ( 5) exhibit potent immunosuppressive activity (IC 50 8.1 and 2.7 μmol·L −1, respectively) against human T cell proliferation at a non-cytotoxic concentration.