Antiallergic Activity of Curcuma longa

Antiallergic activities of extracts from the rhizome of Curcuma longa L. were studied. n-Hexane (Hex), benzene (Benz), ethyl acetate (AcOEt), n-buthanol (BuOH) and water extracts from the crude drug were prepared, and their volatile oils and curcuminoids were analysed by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Eight volatile oils including turmerones were detected in the Hex and Benz extracts, whereas curcuminoids such as curcumin, monodemethoxycurcumin and bisdemethoxycurcumin were detected in the Benz and AcOEt extracts. The volatile oil and curcuminoid contents were very low in the BuOH and water extracts. Their antiallergic activities (types I, II, III and IV) were examined in mice and rats. The five extracts moderately to markedly inhibited the histamine release induced by compound 48/80 from the rat peritoneal mast cells (type I). The potency order was AcOEt extract>Benz extract≒BuOH extract>water extract≒Hex extract. The AcOEt extract suppressed the dye extravasation in the rat passive cutaneous anaphylaxis (type I) test at 300 mg/kg, p.o., whereas the Hex, Benz and AcOEt extracts neither affected the rat reverse cutaneous anaphylaxis (type II), nor changed the mouse reverse passive Arthus reaction (type III) at 300 mg/kg, p.o. The Hex, Benz and AcOEt extracts significantly inhibited the delayed type hypersensitivity (type IV) in mice. These findings show that 1) Curcuma longa extracts had suppressive activities on allergy types I and IV, and 2) the AcOEt extract is the most potent in exerting these effects. Thus, curcuminoids may be the active principles responsible for the antiallergic activities of Curcuma longa.