Cangumycins A-F, six new angucyclinone analogues with immunosuppressive activity from Streptomyces / 中国天然药物

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 8.1 and 2.7 μmol·L, respectively) against human T cell proliferation at a non-cytotoxic concentration.