Crude triterpenoid saponins from Anemone flaccida ( Di Wu ) exert anti-arthritic effects on type II collagen-induced arthritis in rats

Background Anemone flaccida Fr . Schmidt (Ranunculaceae) (Di Wu in Chinese) is used to treat punch injury and rheumatoid arthritis (RA). However, the active compounds and underlying mechanism of action mediating the anti-arthritic effects of A. flaccida remain unclear. This study aims to evaluate the underlying action mechanism of A. flaccida crude triterpenoid saponins (AFS) on RA using a type II collagen (CII)-induced arthritis (CIA) rat model, and to assess the anti-inflammatory effects of the main active compounds of AFS, namely flaccidoside II, anhuienoside E, glycoside St-I4a, hemsgiganoside B, hederasaponin B, and 3-O-α-l-rhamnopyranosyl (1 → 2)-β-d-glucopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl (1 → 6)-β-d-glucopyranosyl ester.