Lanostane Triterpenoids from Kadsura coccinea: Four New Carbon Frameworks and Distinct Hsp90 Binding Modes.

Twenty new lanostane triterpenoids, kadsuracoccinins A-T (1-20, respectively), were isolated from the stems of Kadsura coccinea, with compounds 1-7 constituting four new carbon scaffolds elucidated by NMR analysis, X-ray diffraction, GEMSTONE-NOE-aided fc-rDG/DDD, and ECD calculations. Luciferase-refolding, NMR STD, and SPR assays revealed compounds 4 and 8-10 as the first lanostane-type Hsp90 inhibitors, which bind Hsp90 through non-N-terminal modes, with compound 8 exhibiting a KD of 4.04 μM.