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.