Research of Bioavailability of Dietary Polyphenols in the Cells

以Caco-2细胞、肝细胞株和结肠WiDR细胞为研究对象，研究了饲料中多酚类物质的生物利用度。1.芹菜素-O-葡萄糖苷在Caco-2细胞中水解成糖苷元后进入Caco-2细胞内，而其C-葡萄糖苷则不能。以0.07%的封闭度将苷元释放到基侧相，其结合形式为1.1%。2.将不同种类的黄酮类化合物加入到HepG2细胞中，并测定其核内掺入量。它们在孵育后30分钟和60分钟的参入率最高。当细胞核暴露于活性氧时，B环上具有邻苯二酚结构的黄酮类化合物可以抑制DNA氧化产物8-OHdG3的形成。黄酮型类黄酮在吸收阶段被特异性地转化为新的代谢物3-氨基形式。氨基形式保持了抗氧化活性和调节蛋白质功能的能力，而且是难结合的。氨基形式被认为是体内黄酮类化合物的活性形式。4.当多种多酚的混合物加入到Caco-2细胞中时，异戊烯基酚青蒿素C很容易被掺入并释放到基侧相，而不接收任何结合物。5.青蒿素C也以不变的形式掺入HepG2细胞中，并以剂量依赖的方式抑制细胞内DNA的氧化。口服剂量青蒿素C可显著防止小鼠结肠内异常隐窝病灶的形成。青蒿素C可通过刺激p21的表达，使细胞停滞于G_0/G_1期。因此，黄酮醇和戊二烯基酚是生物可利用的，因为前者被代谢成更活跃的形式，而后者在吸收过程中难以结合。

Bioavailability of dietary polyphenols was investigated using intestinal Caco-2, hepatic HepG2 and colonic WiDr cells.1.Apigenin-O-glucoside was incorporated into Caco-2 cells after hydrolyzed to aglycone, but its C-glucoside was not. The aglycone was released to the basolateral phase by 0.07% of the closed and its conjugated forms was by 1.1%.2.Various flavonoids were added to HepG2 cells and determined in the incorporated amounts into nuclei. They gave the maximum incorporation at 30 and 60 min after incubation. When the nuclei were exposed to active oxygens, flavonoids that possessed catechol structure in B ring were available to suppress formation of a DNA-oxidized products 8-OHdG.3.Flavonol type of flavonoids was specifically transformed to a novel metabolite, 3-amino forms, at the absorption step. The amino forms maintained the potencies for antioxidative activity and for protein fluction-modulating and additionally were refractory to be conjugated. Amino forms were considered to be an active form of flavonoids in the body.4.When a mixture of various polyphenols was added to Caco-2 cells, a prenyl phenol artepillin C was easily incorporated and released to the basolateral phase without receiving any conjugations.5.The artepillin C was also incorporated into HepG2 cells unchanged in form and suppressed the oxidation of intracellular DNA in a dose-dependent manner. Oral dose of artepillin C significantly prevent a formation of aberrant crypt foci in mouse colon. The dose of artepillin C to WiDr induced the cell arrest at G_0/G_1 phase through stimulating expression of p21.Thus, flavonols and prenyl phenol were found to be bioavailable since the former was metabolized to more active forms and the latter was refractory to be conjugated in the absorption prpcess.