The Rhizomes of Acorus gramineus and the Constituents Inhibit Allergic Response In vitro and In vivo

Abstract

The rhizomes of Acorus gramineus have frequently been used in traditional medicine mainly for sedation as well as enhancing brain function. In this study, the anti-allergic activity of A. gramineus was investigated. The 70% ethanol extract of the rhizomes of A. gramineus was found to inhibit the allergic response against 5-lipoxygenase (5-LOX)-catalyzed leukotriene (LT) production from rat basophilic leukemia (RBL)-1 cells and beta-hexosaminidase release from RBL-2H3 cells with IC50's of 48.9 and >200 mu g/ml, respectively. Among the 9 major constituents isolated, beta-asarone, (2R,3R,4S,5S)-2,4-dimethyl-1,3-bis (2',4',5'-trimethoxyphenyl) tetrahydrofuran (AF) and 2,3-dihydro-4,5,7-trimethoxy-1-ethyl-2-methyl-3-(2,4,5-trimethoxyphenyl)indene (Al) strongly inhibited 5-LOX-catalyzed LT production in A23187-treated RBL-1 cells, Al being the most potent (IC50=6.7 mu M). Against beta-hexosaminidase release by antigen-stimulated RBL-2H3 cells, only Al exhibited strong inhibition (IC50=7.3 mu M) while beta-asarone and AF showed 26.0% and 39.9% inhibition at 50 mu M, respectively. In addition, the ethanol extract of A. gramineus showed significant inhibitory action against the hapten-induced delayed hypersensitivity reaction in mice by oral administration at 200 mg/kg. Therefore, it is suggested that A. gramineus possesses anti-allergic activity and the constituents including beta-asarone and Al certainly contribute to the anti-allergic activity of the rhizomes of A. gramineus.