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

Abstract

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.