Anti-allergic components from the peels of Citrus unshiu

In a bioassay-guided search for anti-allergic compounds from higher plants of Korea, polymethoxyflavones, 3 ',4',5,6',7,8-hexamethoxyflavone (I), 5-hy droxy-3',4',6,7,8-pentamethoxyflavone (II) and 3',4',5,7,8,-pentamethoxyfla vone (III) have been isolated from the immature peels of Citrus unshiu. Str uctures of these compounds were elucidated on the basis of spectroscopic te chniques. Compounds I and II inhibited dose-dependently histamine release f rom the rat peritoneal mast cells activated by compound 48/80 or anti-DNP I gE.