Studies on the Constituents of Sophora Species. IV. : Constituents of the Root of Sophora angustifolia SIEB. et ZUCC. (1)

From the root of Sophora angustifolia SIEB. et ZUCC., two kinds of new natural flavonoids, named isoanhydroicaritin (I), mp 275°, C21H26O6, and "nor-anhydroicaritin" (IX), mp 226°, C20H18O6, were isolated, together with xanthohumol and isoxanthohumol. The structures of I and IX were elucidated as 8-isopentenyl-rhamnocitrin and 8-isopentenyl-kaempferol, respectively, by the spectral properties of them and their derivatives and by the procedure shown in Chart 2. Although "nor-anhydroicaritin" had previously been derived from nor-icariin (XI) by acid-hydrolysis and subsequent degradation with alkali and given the name by Akai, et al.14), its direct isolation from a natural source has never been reported.