Kadcoccitones A and B, Two New 6/6/5/5-Fused Tetracyclic Triterpenoids from Kadsura coccinea

A pair of new triterpenoid epimers, kadcoccitones A (1) and B (2), together with a new biogenetically related compound kadcoccitone C (3), were isolated from Kadsura coccinea. The epimers featured an unprecedented carbon skeleton with a 6/6/5/5-fused tetracyclic ring system unit and a C-9 side chain. Their structures were determined by spectroscopic data, ECD calculation, and single-crystal X-ray diffraction. Compounds 1 and 3 showed anti-HIV-1 activity with an EC50 value of 47.91 and 32.66 mu g/mL, respectively.