Clinoposides A–F: meroterpenoids with protective effects on H9c2 cardiomyocyte from Clinopodium chinense

Six novel flavonoid–triterpene saponin meroterpenoids, clinoposides A–F (1–6), with two unusual skeletons were isolated from Clinopodium chinense. Clinoposides A–F represent a new class of isopentenyl flavonoid saponin. Their structures were determined based on spectroscopic data and chemical methods. The relative and absolute stereochemistries were assigned using a combination of NOESY and ECD. A possible biogenetic pathway for 1–6 is proposed. The protective effects of clinoposides A–F against H2O2-induced H9c2 cardiomyocyte injury were tested, and all compounds exhibited significantly dose-dependent effects, clinoposides B, D and F showed better protective effects as evidence by increased levels of SOD, CAT and GSH-Px but reduced MDA, LDH, caspase-3 and -9 levels.