白花蛇舌草黄酮类成分大鼠在体肠吸收研究

In situ intestinal absorption of flavonoids from Hedyotis diffusa in rats

目的考察白花蛇舌草醇提物中5种黄酮类成分在大鼠肠道的吸收特性。方法采用大鼠在体单向肠灌流模型,运用HPLC-DAD法测定肠灌流液中芦丁、异槲皮苷、槲皮苷、槲皮素和山柰酚,计算各黄酮类成分在大鼠小肠的吸收参数。结果白花蛇舌草黄酮类成分在大鼠肠道的有效渗透系数（Peff）均较小;白花蛇舌草总黄酮质量浓度为0.5-4.0 g/L时,吸收速率常数（Ka）、Peff值差异无显著性;在2.0 g/L下,芦丁、异槲皮苷、槲皮苷、槲皮素和山柰酚的Ka分别为0.011 3、0.015 4、0.010 2、0.030 5、0.027 5 min-1;芦丁和异槲皮苷在不同肠段的Ka顺序分别为回肠〉十二指肠〉空肠≈结肠,空肠〉十二指肠〉回肠≈结肠。结论白花蛇舌草中5种黄酮类成分吸收均呈一级动力学过程,提示为被动扩散吸收;各黄酮成分之间的吸收有差异性,黄酮苷类成分的Ka值小于黄酮苷元;各黄酮成分在不同肠段均有吸收,芦丁和异槲皮苷的最佳吸收部位分别为回肠和空肠。

Objective To investigate the intestinal absorption characteristics of five kinds of flavonoids from Hedyotis diffusa extract in rats. Methods The in situ rat single-pass intestinal perfusion model was used. The contents of rutin, isoquercitrin, quercetin, kaempferol, and quercetin in perfusates were determined by HPLC-DAD, and the rat intestinal absorption parameters of flavonoids were calculated. Results In perfusion model, the effective permeability coefficients （Peff） of all components were low. The absorption rate constant （Ka） and Peff had no significant difference when the concentration of total flavonoids from H. diffusa was 0.5-4.0 g/L. In the 2.0 g/L concentration, Ka ofrutin, isoquercitrin, quercetin, kaempferol, and quercetin were 0.011 3, 0.015 4, 0.010 2, 0.030 5, and 0.027 5 min^-1, respectively; The Ka sequences of rutin and isoquercitrin in different intestinal segments were ileum 〉 duodenum 〉 jejunum ≈ colon and jejunum 〉 duodenum 〉 ileum ≈ colon. Conclusion The absorption of the five flavonoids from H. diffusae is a first-order process with the passive diffusion mechanism. The absorption rates of each flavonoid are significantly different. The absorption rate of flavonoid glycosides is lower than that of aglycones. The flavonoids from H. diffusa could be absorbed in all the intestinal segments. The best parts of intestine to absorb rutin and isoquercitrin are ileum and jejunum.