Inhibitory effects of tea catechins and O-methylated derivatives of (-)-epigallocatechin-3-O-gallate on mouse type IV allergy

The inhibitory effects of tea catechins, the O-methylated derivatives of(-) -epigallocatechin-3 -O-gallate (EGCG), and the polyphenol extracts from tea leaves (Camellia sinensis L.) on oxazolone-induced type TV allergy in male ICR mice were investigated. Four major tea catechins and two O-methylated derivatives, (-)-epigallocatechin-3-O-(3-O-methyl)gallate (EGCG3"Me) and (- )epigallocatechin-3-O-(4-O-methyl)gallate (EGCG4"Me), showed significant in hibitory effects on mouse type TV allergy after a percutaneous administrati on at a dose of 0.13 mg/ear. Among tea catechins, the compounds including g alloyl moieties, such as EGCG and (-)-epicatechin-3-O-gallate (ECG), showed the strongest inhibitory activities on mouse type IV allergy. The inhibito ry activities of EGCGB"Me and EGCG4"Me were higher than that of EGCG at a d ose of 0.05 mg/ear. Polyphenol extract from tea leaves of Benihomare cultiv ar, which includes EGCG3''Me, strongly inhibited mouse type TV allergy afte r percutaneous administration in comparison with that from Yabukita cultiva r, which does not include EGCG3"Me, at doses of 0.05 and 0.13 mg/ear. EGCG3 "Me is thought to contribute, at least in part, to the inhibitory ability o f Benihomare tea leaves on mouse type IV allergy. EGCG and the polyphenol e xtracts from Benihomare and Yabukita tea leaves also inhibited mouse type I V allergy by oral administration at 1 h before the sensitization and at 1 h before the challange with oxazolone. Therefore, daily intake of tea drinks could have potential to prevent type IV allergy.