Glucurono- and sulfo-conjugation of kaempferol in rat liver preparations and cultured hepatocytes were studied using high-performance liquid chromatography (HPLC) with two distinctly different elution solvents. Kaempferol glucuronides and sulfates were produced by treating kaempferol with microsomes plus UDPGA or with cytosol plus PAPS, respectively. HPLC analysis of the conjugates revealed one major and three minor glucuronides with solvent A and one sulfate with solvent B. Kaempferol metabolites produced by cultured hepatocytes also consisted of four glucuronides and one minor sulfate, all of which corresponded to their respective in vitro-produced conjugates in the liver subcellular preparations. The relative proportion of kaempferol sulfate accounted for about 9% of the total conjugates in the cultured hepatocytes. The kinetic data on glucurono- and sulfo-conjugation of kaempferol by the liver subcellular preparations correlated well with the preferential production of kaempferol glucuronides in the cultured hepatocytes. Glucurono- and sulfo-conjugation of 3-, 5- and 7-OH flavones in the liver subcellular preparations were also kinetically characterized. 7-OH flavone was predominantly conjugated to form a glucuronide compared to 3- and 5-OH flavones. These data suggest that glucuronidation at the 7-OH position on the A-ring is a major metabolic pathway of kaempferol in hepatic cells.
使用高效
液相色谱(HPLC)与两种截然不同的洗脱溶剂,研究了大鼠肝制备物和培养的肝细胞中
山柰酚的
葡糖醛酸化和
硫酸化结合。
山柰酚葡糖醛酸和
硫酸是通过微粒体加U
DPGA或胞质液加P
APS处理
山柰酚分别产生的。对结合物的HPLC分析显示,溶剂A中有一个主要和三个次要的
葡糖醛酸,溶剂B中有一个
硫酸。由培养的肝细胞产生的
山柰酚代谢物也包括四个
葡糖醛酸和一个次要
硫酸,这些都与肝亚细胞制备物中体外产生的相应结合物相符。在培养的肝细胞中,
山柰酚硫酸约占全部结合物的9%。肝亚细胞制备物中对
山柰酚的
葡糖醛酸化和
硫酸化结合的动力学数据与培养的肝细胞中
山柰酚葡糖醛酸的优先形成有很好的相关性。肝亚细胞制备物中3-、5-和
7-羟基黄酮的
葡糖醛酸化和
硫酸化结合也被动力学特征化。与3-和
5-羟基黄酮相比,
7-羟基黄酮主要被结合形成
葡糖醛酸。这些数据表明,A环上7-OH位置的
葡糖醛酸化是
山柰酚在肝细胞中的主要代谢途径。