4,21‐Secovincanol, a Novel Immunosuppressive Monoterpenoid Indole Alkaloid from Kopsia Hainanensis

Abstract 4,21‐Secovincanol ( 1 ), a novel C‐21/N‐4 cleavage monoterpenoid indole alkaloid, along with four analogs ( 2 – 5 ), were obtained from the aerial parts of Kopsia hainanensis . Structurally, compound 1 might be a derivative of epivincanol ( 2 ) via C‐21/N‐4 cleavage. Their structures were confirmed by means of comprehensive spectroscopic data analysis and comparison with the reported data. All isolates significantly inhibited Con A‐stimulated mice splenocytes proliferation at 10–40 μM in a dose‐dependent manner in vitro . Especially, compound 3 exhibited potent activities comparable to positive control (Dexamethasone, DXM).