Anti-allergic substances contained in the pollen of Cryptomeria japonica possess diverse effects on the degranulation of RBL-2H3 cells.

Following prolonged exposure to some of the flavonoids with RBL-2H3 cells, secretion of hexosaminidase, a granule constituent, stimulated by an immunologic was enhanced. RBL-2H3 cells do not normally respond to polybasic secretagogues, but as reported here, they do so after prolonged exposure. Effect of flavonoids on secretion of hexosaminidase was also investigated. Of the thirteen flavonoids, quercetin and fisetin were the most potent inhibitors. A structure-activity study indicated that the position, number, and substitution of the hydroxy group of the B ring and saturation of the C2-C3 bond are important factors affecting flavonoid inhibition of secretary granules in RBL-2H3 cells.