Identification of a methylated tea catechin as an inhibitor of degranulation in human basophilic KU812 cells.

We examined the constituents of tea that had an inhibitory effect on the degranulation process in the human basophilic cell line, KU812. Among the constituents purified from a extract of 'Benihomare' oolong tea by column chromatography, a methylated (-)-epigallocatechin gallate ((-)-epigallocatechin 3-O-(3-O-methyl) gallate) was found to inhibit the degranulation of KU812 cells that had been stimulated with calcium ionophore A23187. The inhibitory effect of this methylated (-)-epigallocatechin gallate on degranulation was greater than that of (-)-epigallocatechin gallate. This result indicates that methylation of (-)-epigallocatechin gallate may be an effective modification for the catechin to inhibit degranulation from human basophils.