[Study on flavonoids in seeds of Hovenia dulcis]

Four flavanoids were isolated from the seed of Hovenia dulcis Thunb. On the basis of physicochemical properties and spectroscopic analysis, their structures were identified as dihydrokaempferol (I), quercetin (II), (+)-3,3',5',5,7-pentahydroflavanone (III) and (+)-dihydromyricetin (IV). Among them, III was a new compound; I and IV were first isolated from genus Hovenis.