In vitro human intestinal microbiota biotransformation of nobiletin using liquid chromatography–mass spectrometry analysis and background subtraction strategy

Abstract In this study, the in vitro biotransformation of nobiletin by human intestinal microbiota, which is a bioactive polymethoxyflavone widely presented in Citrus plants, has been investigated via utilizing an anaerobic incubation protocol. The incubation samples were detected using high‐performance liquid chromatography/quadrupole time‐of‐flight mass spectrometry. A background subtraction strategy incorporated in Microsoft Office was employed to eliminate the interferences in medium and feces. The parent and three metabolites sinensetin, 5‐hydroxy‐6,7,3′,4′‐tetramethoxyflavone, and 5‐demethylnobiletin were detected and identified based on the characteristics of their protonated molecules. The proposed metabolic pathway revealed that nobiletin went through phase I metabolism including demethylation and demethoxylation in human intestinal microbiota. The characterization of nobiletin metabolic profile transformed by human intestinal bacteria would be helpful for understanding its efficacy and action mechanism.