The hydroalcoholic extract of Cassia alata (Linn.) leaves and its major compound rhein exhibits antiallergic activity via mast cell stabilization and lipoxygenase inhibition

Leaves of Cassia alata (family: Caesalpiniaceae) are ethnomedically claimed as anti-asthmatic. In the current study we aimed to investigate the anti-allergic activities of hydro-methanolic extract of Cassia alata (Linn.) and its constituents rhein and kaempferol on triple antigen/sheep serum-induced mast-cell degranulation in rats. Antiallergic activity of hydroalcoholic extract of Cassia alata along with its two components rhein and kaempferol was evaluated using in vivo mast cell stabilization assay. Inhibitory effect on lipoxygenase (LOX) enzyme was also evaluated in vitro. Further chemical standardization of Cassia alata extract was done using rhein and kaempferol by HPTLC-densitometric method. The hydroalcoholic extract of Cassia alata significantly inhibited mast cell degranulation at 200mg/kg dose. Both chemical constituents rhein and kaempferol also showed potent (>76%) inhibition of mast-cell degranulation at 5mg/kg. Extract and rhein inhibited LOX enzyme with IC50 values of 90.2 and 3.9μg/mL, respectively, whereas kaempferol was inactive. Our results suggest that Cassia alata exhibit anti-allergic activity through mast cell stabilization and LOX inhibition. Thus, Cassia alata or its active constituents could be potential alternative treatment for allergic diseases.