Background: Apple skins are a rich source of flavonols, in particular quercetin (Q) glycosides. The objective of the present study was to investigate the presence of Q metabolites in plasma, various tissues, and excreta when the commercial broiler chicken's diet was supplemented with Q (0, 50, 150, 300, or 600 mg kg(-1) body weight per day), an apple skin extract (ASE; 50, 150 mg total phenolics kg(-1) body weight per day), or a dried apple skin powder (ASP; 50 mg total phenolics kg(-1) body weight per day).
Results: When Q was supplemented for 3 days, Q sulfate, Q glucuronide, Q glucoside glucuronide, Q glucoside sulfate, and isorhamnetin glucoside were detected by liquid chromatography-tandem mass spectrometry in the liver and duodenum. Deconjugated Q was also detected in the breast and thigh tissues of ASE- and ASP-supplemented broilers. Regardless of the source or concentration of Q, the antioxidant capacity measured by ferric reducing ability of plasma (FRAP) assay in the plasma and tissues of the broilers did not change significantly.
Conclusions: As far as is known, this is the first report to demonstrate that Q and its glycosides can be absorbed and metabolized by broiler chickens.