Siphonaxanthin (3,19,3'-trihydroxy-7,8-dihydro-β,ε-caroten-8-one) is a carotenoid found in green algae that exhibits potent anti-inflammatory activities. We previously reported that ingested siphonaxanthin accumulates in various organs of mice
however, its metabolic conversion remains largely unknown. In this study, we isolated three siphonaxanthin dehydrometabolites and determined their chemical structures. Two of these metabolites were obtained using the postmitochondrial supernatant prepared from mouse liver, whereas the third was obtained using the postmitochondrial supernatant prepared from rat liver. The human liver S9 fraction also generated two metabolites: one was identical to one of the rat metabolites, and the other was identical to one of the mouse metabolites.