Tissue distribution of naringenin conjugated metabolites following repeated dosing of naringin to rats

Background: Naringin is a major antioxidant in Citrus fruits and herbs. To clarify molecular forms distributed to various tissues, we investigated tissue distribution of naringin and relevant metabolites in rats after repeated dosing. Methods: Male Sprague-Dawley rats were orally administered naringin (210 mg/kg) twice daily for eight days. At 6 h post the 17(th) dose, various tissues including liver, kidney, heart, spleen and brain were collected and analyzed by HPLC method before and after hydrolysis with β-glucuronidase and sulfatase, individually. Results: The free forms of naringin and naringenin were not detected in all the tissues assayed. Liver contained the highest concentration of naringenin sulfates, followed by spleen, heart, brain and kidney. Naringenin glucuronides were present in liver and kidney, but not in spleen, brain and heart. Conclusion: The bioavailability of naringenin glucuronides and sulfates supported its application for personalized medicine.