Intestinal absorptive characteristics of andrographolide and dehydroandrographolide in extract from Andrographis paniculata in rats / 中草药

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.