Kawada T, Suzuki T, Takahashi M, Iwai K
Toxicol Appl Pharmacol. 1984 Mar 15;72(3):449-56. doi: 10.1016/0041-008x(84)90121-2.
Gastrointestinal absorption of capsaicin and dihydrocapsaicin was studied in rats in vivo and in situ. Rapid absorption of capsaicin or dihydrocapsaicin from stomach and small intestine occurred in vivo. About 85% of the dose was absorbed in the gastrointestinal tract within 3 hr. In situ, within 60 min after the administration of capsaicin and dihydrocapsaicin into stomach, jejunum, and ileum, about 50, 80, and 70% of the respective dose had disappeared from the lumen. When 2,4-dinitrophenol or NaCN was added, no significant reduction in uptake of [3H]dihydrocapsaicin was observed in the jejunum. These results suggested that capsaicin and its analogs were absorbed by a nonactive process in jejunum. [3H]Dihydrocapsaicin was mainly absorbed via the portal system but not a mesenteric lymphangial one. The radioactivity in the portal blood was composed of 85% of [3H]dihydrocapsaicin and 15% of its metabolite (8-methyl nonanoic acid) bound to the albumin fraction. Dihydrocapsaicin-hydrolyzing enzyme activity was found in jejunal tissue. These results suggest that capsaicin and its analogs partly received a first-pass effect, i.e., metabolism of a compound following first absorption in the gastrointestinal tract. It is concluded that capsaicin and its analogs are readily transported to the portal vein through the gastrointestinal tract by a nonactive process and partly metabolized during absorption.
在大鼠体内和原位研究了辣椒素和二氢辣椒素的胃肠道吸收情况。在体内，辣椒素或二氢辣椒素可从胃和小肠快速吸收。约85%的剂量在3小时内被胃肠道吸收。在原位，将辣椒素和二氢辣椒素分别注入胃、空肠和回肠后60分钟内，各自剂量的约50%、80%和70%已从肠腔中消失。当加入2,4-二硝基苯酚或NaCN时，空肠中[3H]二氢辣椒素的摄取未见明显减少。这些结果表明，辣椒素及其类似物在空肠中通过非主动过程被吸收。[3H]二氢辣椒素主要通过门静脉系统吸收，而非肠系膜淋巴管。门静脉血中的放射性由85%的[3H]二氢辣椒素和15%与其白蛋白部分结合的代谢产物（8-甲基壬酸）组成。在空肠组织中发现了二氢辣椒素水解酶活性。这些结果表明，辣椒素及其类似物部分受到首过效应，即在胃肠道首次吸收后化合物的代谢。结论是，辣椒素及其类似物通过非主动过程容易通过胃肠道转运至门静脉，并在吸收过程中部分代谢。
