ABSTRACT
OBJECTIVE: To investigate the enhancing effect of borneol on the absorption of chlorogenic acid (CGA) with two different biological models and to evaluate the correlation of these two models. METHODS: The in situ rat perfusion model was used to investigate the enhancing effect of borneol on the absorption of CGA. The in vivo pharmacokinetics study was carried out to evaluate the correlation of the two-compartment open model. RESULTS: With the in situ rat perfusion model, the absorption rate constant (Ka) of CGA was 0.083 4 h-1, which was up to 1.58-fold higher by borneol. The results of in vivo pharmacokinetics study in rats suggested that 0.04% borneol could increase the relative bioavailability by 116.02% and maximum plasma concentration increased slightly. The consistent result of these two different absorption models was provided (r=0.941). CONCLUSION: Borneol could promote the oral absorption of CGA.
ABSTRACT
Objective: To investigate the intestinal absorptive characteristics of andrographolide (A) and dehydroandrographolide (DDA) in the extract of Andrographis paniculata in rats. Methods: The intestine of rat was cannulated for in situ perfusion. UV was used to determine the concentration of phenol red, and HPLC was used to determine the concentration of A and DDA. The effects of drug concentration, pH value, and absorption site on the absorption had been studied. Results: In 111.22-335.78 μg/mL dose range of A. paniculata extract, Ka and P of A were reduced with the increase of concentration. With the pH value increasing from 5.34 to 6.38, Ka and P were increased slightly. With the pH value increasing from 6.38 to 7.40, Ka and P had a downward trend. A was absorbed in various sections of intestines, and the P descended in the order of duodenum, jejunum, ileum, and colon. In 111.22-222.78 μg/mL dose range of A. paniculata extract, Ka and P were reduced with the increase of concentration. In 222.78-335.78 μg/mL dose range, Ka and P had no change with the increase of concentration. Under the condition of pH 5.34, the absorption was better. With the pH value increasing from 5.34 to 7.40, Ka and P showed a slight downward trend, and P descended in the order of ileum, jejunum, colon, and duodenum. Conclusion: The intestinal absorption mechanism of A and DDA in A. paniculata extract is not just passive transport, but also including the carrier medium transport which are both affected by pH value. The best absorption site of A is duodenal, and the best absorption site of DDA is ileumother. Other components may have no significant influence to the intestinal absorption of A, but they may promote the intestinal absorption of DDA.
ABSTRACT
OBJECTIVE: To explore the stomach and intestine absorption kinetics of chlorogenic acid in rats. METHODS: In situ perfusion model was employed to investigate the absorption characteristics of chlorogenic acid in rats. Ultraviolet spectrophotometry and HPLC method were used for phenolsulfonphthalein and chlorogenic acid determination respectively. RESULTS: The absorption rate per hour of chlorogenic acid(40 μg · mL-1) in stomach was 7.77%. The intestinal absorption rate constants of chlorogenic acid at concentration of 20, 40 and 80 μg · mL-1 were 0.0521, 0.052 5 and 0.0472 h-1 respectively. The intestinal absorption rate constants at duodenum, jejunum, ileum, and colon were 0.0492, 0.0395, 0.0630 and 0.0318 h-1, respectively. After the bile duct was ligated, the intestinal absorption rate constant of chlorogenic acid at 40 μg · mL-1 was 0.0662 h-1. CONCLUSION: Drug concentration has no dramatic influence on the intestinal absorption of chlorogenic acid in rats. The absorption mechanism is passive absorption and complies with first-order kinetics process. The absorption at duodenum and ileum is better than that at jejunum and colon. Bile excretion has no effect on absorption of chlorogenic acid in rats.