CHEN Pengcheng1,3, HOU Jingyu1,3, HU Jie2,3, GONG Zipeng1,3, WANG Yonglin1,3*
The absorption kinetic characteristics of the main active components in extract of Cortex Eucommiae, including geniposidic acid (1), neochlorogenic acid (2), chlorogenic acid (3) and cryptochlorogenic acid (4) in rats' intestine, were investigated by adopting the in situ rat circulation intestinal perfusion model. A UPLC-MS/MS method was established for the determination of 1 - 4, and their absorption at different conditions, including pH values, sample concentrations, bile and P-gp inhibitors was investigated. As a result, the absorption of 1 was poor at pH 7.4, while that of 2 and 4 was significantly different at different pH values. But 3 was insensitive to pH values. The accumulated absorption rates (3 h, A) of 2 and 3 at middle concentrations (4.0 mg/ml) were higher than that at high concentrations (8.0 mg/ml). There was saturation phenomenon of absorption when they were at high concentrations. The bile significantly inhibited the absorption of 1 - 4. However, P-gp inhibitor had no effect on the absorption of the Cortex Eucommiae extract. The results indicated that the absorption of 1 - 4 existed in the whole intestinal segments, while the main absorption site was at the small intestine. It also suggested that 1 - 4 might not be the substrates of P-gp.