Highly oxidized rearranged derivatives of quinochalcone C-glycosides from Carthamus tinctorius

Safflopentsides A−C (1−3), three highly oxidized rearranged derivatives of quinochalcone C-glycosides, were isolated from the safflower yellow pigments. Their structures were determined based on a detailed spectroscopic analysis (UV, IR, HR-ESI-MS, 1D and 2D NMR), and the absolute configurations were confirmed by the comparison of experimental ECD spectra with calculated ECD spectra. Compounds 1−3 have an unprecedented cyclopentenone or cyclobutenolide ring A containing C-glucosyl group, respectively. The plausible biosynthetic pathways of compounds have been presented. At 10 μM, 2 showed strong inhibitory activity against rat cerebral cortical neurons damage induced by glutamate and oxygen sugar deprivation.