Screening flavonoid metabolites of naringin and narirutin in urine after human consumption of grapefruit juice by LC-MS and LC-MS/MS.

The main flavonoids in grapefruit juice, naringin and narirutin, were quantified by LC-MS with structural differentiation by LC-MS/MS. After human consumption of grapefruit juice, urine samples were collected for 24 hours and screened for flavonoid metabolites by LC-MS. The metabolite structures (glucuronides, sulfates, and glucuronide sulfates) were then confirmed via their unique fragmentation patterns by LC-MS/MS. To further verify the identity of the common aglycon (naringenin) shared by the metabolites, enzymatic hydrolysis was performed and the resulting products were analyzed. This work demonstrates that LC-MS and LC-MS/MS techniques can be used for fast metabolite screening without extensive sample preparation.