Okicamelliaside, an extraordinarily potent anti-degranulation glucoside isolated from leaves of Camellia japonica.

Guided by anti-degranulation assays, we isolated from leaves of Camellia japonica an ellagic acid glucoside named okicamelliaside. The structure was elucidated as 3,4-dioxoloellagic acid 4'-O-β-D-glucopyranoside by spectroscopic and chemical methods. Okicamelliaside was 12,000 times more potent than the antihistaminic drug, ketotifen fumarate, in inhibiting the degranulation of RBL-2H3 cells.