Novel antiallergic catechin derivatives isolated from oolong tea

Two catechin derivatives (C-1 and C-2) with potent antiallergic activity we re isolated from Taiwanese oolong tea by HPLC techniques. From NMR and FAB- MS analyses, the structures of C-1 and C-2 were elucidated as (-)-epigalloc atechin 3-O-(3-O-methyl)gallate and (-)-epigallocatechin 3-O-(4-O-methyl)ga llate, respectively. The oolong tea leaves contained 0.34% (dry weight) C-1 and 0.20% C-2. Traces of C-2 were detected in only 1 of 15 varieties of gr een tea tested. C-1 was detected in 13 of 15 green tea varieties; C-1 was m ost concentrated in tea cultivars classified as Assam hybrids (0.50-0.82% o f dry weight). Quantitative analyses of green tea, oolong tea, and black te a manufactured from same batches of tea leaves showed that neither catechin derivative was produced during the fermentation process. Oral doses of C-1 and C-2 (5-50 mg/kg) Significantly inhibited type I allergic (anaphylactic ) reactions in mice sensitized with ovalbumin and Freund's incomplete adjuv ant. These inhibitory effects exceeded that of the major tea catechin, (-)- epigallocatechin 3-O-gallate, which has known antiallergic properties.