Allergy-Preventive Flavonoids from Xanthorrhoea hastilis

Allergy-preventive activity was demonstrated for an extract of resins from Xanthorrhoea hastilis R. BR. in a search for allergy-preventive substances from natural sources. By bioassay-directed fractionation of this plant extract, a new flavanone, 3′,5′-dihydroxy-7,4′-dimethoxyflavanone (1), and two new chalcones, 3,5,2′-trihydroxy-4,4′-dimethoxychalcone (2) and 5,2′-dihydroxy-3,4,4′-trimethoxychalcone (3), were isolated together with five known...