Biologically active substances in oak gall extracts. Part 11. The antihistamine-like activity of a substance (KC-18) isolated from oak gall extracts.

The effects of the newly isolated antihistamine (KC-18) from the Hungarian oak gall extracts on some actions of histamine have been investigated. Intraperitoneally administered KC-18 into guinea pigs and cats in doses of 2.5-16 mg/kg exerted a significant dose-related inhibition of histamine-induced bronchoconstriction, increase in capillary permeability and hypotension. In guinea pigs, actively sensitized with ovalbumin, 4 mg/kg KC-18 administered intraperitoneally prevented the development of anaphylactic shock following antigenic challenge. Histamine-induced gastric acid secretion in the rat was also dose-relatedly reduced by the intravenous administraton of 72 and 120 mg/kg KC-18. However, KC-18 in doses up to 100 mug/ml did not modify the histamine-induced contraction of the isolated guinea pig ileum.