Determination of apigenin in rat plasma by high-performance liquid chromatography

Apigenin (4',5,7-trihydroxyflavone, AP) belongs to a less-toxic and non-mut agenic flavone subclass of flavonoids, the biotransformation and metabolism of which have been little studied until now. Therefore, this study is focu ssed on the determination of AP in free form. AP was administered to rats v ia the i.p. route (25 mg kg(-1)) and then the blood was collected at 10, 15 , 30 and 45 min after injection. Methanol was used for rat plasma deprotein ization. The HPLC assay (mobile phase, 2% formic acid-acetonitrile-methanol , 40:35:25, v/v; flow-rate, 1 ml min(-1); UV detection at 349 nm) for AP de termination was validated and used for the quantification of AP in rat plas ma. The unknown concentration was calculated from the equation obtained by the least-squares regression analysis (y = 0.521x + 1.130, r(2) = 0.998). T he highest concentration of AP in plasma was found to be 30 min after injec tion. The concentration profile of AP obtained here may contribute to until known results about AP metabolism. They could be applied to other studies of AP or related flavonoids because of favourable effects on human health. (C) 2000 Elsevier Science B.V. All rights reserved.