Mesenteric lymphatic absorption and the pharmacokinetics of naringin and naringenin in the rat.

The hypothesis for this study was that flavanoids and their glycoside are absorbed mainly through the portal vein to enter the liver for biotransformation and are only partially absorbed through the lymphatic duct. To verify this hypothesis, an unconscious, mesenteric lymphatic/portal vein/jugular vein/bile duct/duodenum-cannulated rat model was developed. Naringin was administered at dosages of 600 and 1000 mg/kg, and naringenin was given at 100 and 300 mg/kg by intraduodenal administration. Blood samples collected from the portal vein and jugular vein as well as lymphatic fluid were prepared by protein precipitation and then analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-DAD). Analyses of these samples were doubly confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The results show that, after intraduodenal administration, both compounds were mainly absorbed into portal blood rather than mesenteric lymph, and most of the intact analyte would be eliminated through bile excretion. The area under the concentration (AUC) ratio was defined to represent the absorption ratio for portal vein (AUCportal/AUC(portal+lymph)) and lymph fluid (AUClymph/AUC(portal+lymph)). The results indicate that the portal and lymphatic absorptions for naringin were around 95 and 5.0%, respectively. The respective absorptions for naringenin were around 98 and 2%, respectively.