Chisosiamens A-E, five new ring-intact limonoids with isomerized furan ring from the fruit of Chisocheton siamensis.

Abstract Five new ring-intact limonoids with isomerized furan ring, chisosiamens A–E (1–5), along with four known compounds (6–9) were isolated from the fruit of Chisocheton siamensis Craib. Their structures were elucidated based on 1D and 2D NMR spectroscopic data, HRESIMS, circular dichroism, and exciton chirality method. The biological activities screening showed that new limonoid 5 exhibited significant NO inhibitory activity in LPS-activated RAW 264.7 macrophages (IC50: 10.13 ± 1.40 μM) and 1, 2, 5, and 9 effectively reversed the resistance in MCF-7/DOX cells with the range IC50 values of 10.20–15.06 μM (RI: 4.05–5.98).