Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan.
Arch Biochem Biophys. 2018 May 1;645:126-136. doi: 10.1016/j.abb.2018.03.024. Epub 2018 Mar 22.
Quercetin is a major flavonoid, present as its glycosidic forms in plant foods. In this study, quercetin-3-glucoside (Q3G) was administered intraduodenally to thoracic lymph-cannulated rats, and its lymphatic transport was investigated. The resulting lymphatic and plasma metabolites were identified with LC-MS/MS and compared with those after administration of quercetin aglycone. The total concentration of quercetin metabolites in the lymph was about four times lower than that in the plasma, and quercetin and its methylated form isorhamnetin were detected as their glucuronides, sulfates and diglucuronides both in the lymph and the plasma after Q3G and quercetin administrations. The lymph levels of the glucuronides after Q3G administration were lower than those after quercetin administration, whereas those in the plasma showed the opposite pattern. Both the lymph and plasma levels of the sulfates after Q3G administration were lower than those after quercetin administration. Some of the intestinal metabolites like quercetin monoglucuronides were transported directly into the lymph and the hepatic metabolites like the diglucuronides were eventually transferred from the plasma into the lymph. These results indicate that the absorbed Q3G is partly transported into the intestinal lymph as quercetin metabolites. Deglycosylation in the enterocyte is also suggested to affect the subsequent metabolic pathways.
槲皮素是一种主要的类黄酮，以其糖苷形式存在于植物性食物中。在这项研究中，槲皮素-3-葡萄糖苷（Q3G）被十二指肠内给药于胸部淋巴导管大鼠，并研究其淋巴转运。用 LC-MS/MS 鉴定所得的淋巴和血浆代谢物，并将其与槲皮素苷元给药后的代谢物进行比较。在淋巴中的槲皮素代谢物的总浓度约为血浆中的四倍，并且在 Q3G 和槲皮素给药后，在淋巴和血浆中均检测到槲皮素及其甲基化形式异鼠李素作为其葡萄糖醛酸、硫酸盐和二葡萄糖醛酸苷。Q3G 给药后，葡萄糖醛酸苷在淋巴中的水平低于槲皮素给药后，而在血浆中则相反。Q3G 给药后，硫酸盐在淋巴和血浆中的水平均低于槲皮素给药后。一些肠内代谢物，如槲皮素单葡萄糖醛酸苷，被直接转运到淋巴中，而肝内代谢物，如二葡萄糖醛酸苷，最终从血浆中转移到淋巴中。这些结果表明，吸收的 Q3G 部分作为槲皮素代谢物被转运到肠道淋巴中。在肠细胞中的去糖基化也被认为会影响随后的代谢途径。
