Seven compounds reacting with Dragendorffs″ reagent were detected in extracts from leaves of Orixa japonica Thunberg. Two of them were isolated. By means of chemical and spectral properties, one was shown to be kokusagin, a furoquinoline alkaloid previously isolated from this plant. The second alkaloid was new and called japonine. By spectral comparison with synthetic 2-phenyl- and 3-phenyl-4-quinolones, its structure was established as 1-methyl-2-phenyl-3,6-dimethoxy-4-quinolone. Its chemical behaviour and fragmentation pattern by mass spectrometry are in agreement with this formulation. © 1970.