Biol. Pharm. Bull. 29(4) 689—692 (2006)

used in the brewing industry to add bitterness and aroma to beer. Hop is also used in folk medicine as a tranquilizer, and in Japan, it is formulated in over the counter (OTC) drugs for depression of the central nervous system or the activation of gastric function. Moreover, it has been reported that the hop shows a wide range of the physiological roles, such as an inhibitory effect on the bone resorption, cancer chemopreventive activity, inhibition of tumor promotion by 12-Otetradecanoylphorbol-13-acetate in mouse skin, an estrogenic property of the phyto-estrogen, 8-prenylnaringenin, and the inhibition of nitric acid production. Allergic diseases such as hay fever, atopic dermatitis, food allergy and bronchial asthma are increasing in prevalence in most countries of the developed world. These allergic diseases are classified as type I allergies. Basophils and mast cells play a crucial role in the initiation of such types of allergies. On the other hand, it has been reported that tea, peppermint and tomato skin showed antiallergic properties by inhibiting the degranulation of basophils and mast cells. Antiallergic properties of these plant extracts are attributable to their flavonoids and flavonoid glycosides. It is well known that hop contains polyphenols, including flavonoids and flavonoid glycosides. However, relatively little is known about the antiallergic properties of hop extracts. Therefore, we investigated the antiallergic properties of hop extracts by evaluating the inhibition of histamine release from rat peritoneal mast cells and human basophilic KU812 cells. The effects of hop extracts on the nasal rubbing and the sneezing in allergic rhinitis models were also studied in mice.