Isolation of five new flavonoids from Melicope triphylla.

Five new flavonoids, 5,8-dihydroxy-3,7-dimethoxy-3',4'-methylenedioxyflavone (1), 7-hydroxy-3,5-dimethoxy-3',4'-methylenedioxyflavone (2), 7-(2,3-dihydroxy-3-methylbutoxy)-3,5-dimethoxy-3',4'-methylenedioxyflavone (3), 7-(2,3-dihydroxy-3-methylbutoxy)-3,3',4',5-tetramethoxyflavone (4), and 7-(2,3-dihydroxy-3-methylbutoxy)-3,3',4',5,8-pentamethoxyflavone (5), were isolated from the leaves of Melicope triphylla. In addition, six known flavonoids were detected: 3,4',5-trihydroxy-3',7,8-trimethoxyflavone (6), 5,7-dihydroxy-3-methoxy-3',4'-methylenedioxyflavone (7), 4',5,7-trihydroxy-3,3'-dimethoxyflavone (8), 4',7-dihydroxy-3,3',5,8-tetramethoxyflavone (9), 4',7-dihydroxy-3,3',5-trimethoxyflavone (10), and 4',5,7-trihydroxy-3,3',8-trimethoxyflavone (11). The new compound structures were determined by spectroscopic methods. Compounds 1-5 did not exhibit any ichthyotoxic activity against Japanese killifish (medaka in Japanese) (Oryzias latipes var.) at 10 ppm.