Characterization of in vivo and in vitro metabolites of furanodiene in rats by high performance liquid chromatography-electrospray ionization mass spectrometry and nuclear magnetic resonance spectra.

Furanodiene is an active ingredient of Rhizoma Curcumae, a very famous Traditional Chinese Medicine (TCM) widely used for the treatment of cancer. Although the anti-tumor effect of furanodiene has well been established, its metabolic profile in vivo and in vitro is still unclear. In the present study, the metabolites of furanodiene in rats were studied. After oral administration of furanodiene, the rats' urine, feces and bile were collected and produced seven metabolites by the use of macroporous adsorption resin chromatography, and semi-preparative high performance liquid chromatography. Their structures were identified by mass spectrometry and NMR data including (1)H, (13)C, and two-dimensional NMR data. All of these metabolites were phase I metabolites, with three new compounds including 2β-hydroxyl-aeruginolactone (2), 14-hydroxyl-aeruginolactone (3), 1β,8β-dihydroxyeudesm-4,7(11)-dien-8α,12-olide (4a), and four known compounds, 1β,10α,4α,5β-diepoxy-8α-hydroxy-glechoman-8α,12-olide (1), 1β,8β-dihydroxyeudesm-4(14),7(11)-dien-8α,12-olide (4b), 1β,8β-dihydroxyeudesm-3,7(11)-dien-8α,12-olide (5) and aeruginolactone (6). Interestingly, the metabolite 6 was found to be a primary metabolite in urine, bile and feces. All metabolites were found to be both in urine and bile but only few metabolites except the metabolite 6 presented in feces after oral dose of furanodiene to rats. Furthermore, the metabolic pathways of furanodiene were proposed using an in vitro assay by incubation of furanodiene and its metabolites in vivo with rat liver S9 or liver microsomes. Clearly, aeruginolactone (6) seemed to be a major precursor for other metabolites.