Cytochrome P3A4 inhibitors and other constituents of Fibraurea tinctoria.

Four new furanoditerpenoids, fibrauretin A ( 1), fibrauretinoside A ( 2), epi-fibrauretinoside A ( 3), and epi-12-palmatoside G ( 4), and a new ecdysteroid glucoside, fibraurecdyside A ( 5), together with seven known compounds including two furanoditerpenoids ( 6 and 7), an ecdysteroid ( 8), and four quaternary protoberberine alkaloids ( 9- 12) were isolated from the stems of Fibraurea tinctoria. The structures of 1- 5 were established on the basis of spectroscopic evidence. Among these compounds, palmatine ( 9) and jatrorrhizine ( 10) showed inhibitory effects against cytochrome P450 3A4 (CYP3A4) with IC 50 values of 0.9 and 2.1 microM, respectively.