3,3',4,5'-Tetrahydroxystilbene (I) and 3,3',4,5'-tetrahydroxybibenzyl (II), isolated from the heartwood of Cassia garrettiana Craib (Leguminosae), showed inhibitory effects on antigen-induced histamine release from rat peritoneal mast cells in vitro. The inhibitory effect of I (IC50 = 30.2 microM)
3,3',4,5'-Tetrahydroxystilbene (I), a constituent of Cassia garrettiana, strongly inhibited the anti-IgE-induced histamine release from human basophils in vitro at concentrations of 3 to 30 microM. Considering that disodium cromoglycate showed no significant inhibitory activity in this assay method,