| Bergenin (BN) is a compound of isocoumarin separated from the rhizome of Saxifragaceae. It has antitussive, hepatoprotective, anti-inflammatory, coughs preventing and neuroprotective activities and has been used as an important traditional medicine for the treatment of chronic bronchitis. Until now, more concerns have been focused on the ways of its abstraction and isolation, the pharmacological properties and analysis methods, but little imformation was available about the aspect of biopharmaceutics and pharmacokinetics. In the present study, based on the research of physicochemical properties, in situ perfusion model and in vivo kinetic research were employed to investigate absorptive characters and pharmacokinetics.The physicochemical study clearly indicated that BN has poor water solubility and the dissolution rate was low. As a natural weak acid, BN was easily degraded in basic solution and was stable in acid environment. The value of apparent oil-water partition coefficient was low and exhibited pH-dependent characteristics, which decreased along with the increasing of pH. Its low lipophilicity may lead to low absorption efficiency into the lipid membrane.In situ perfusion experiment suggested that stomach and duodenum could be the most suitable site for BN absorption. In the range of 70～140μg/ml, the absorption mechanism of BN in stomach were rather complex and involved active transport and passive diffusion; while in intestine it exhibited linear kinetics and passive diffusion could be the main manner of the transmembrane process. Due to the instability in basic environment and low lipophilicity, BN was poorly absorbed in gastrointestinal tract. P% of perfusates at concentrations of 70, 140, 210μg/ml were only 3.37, 3.14, and 3.78%, respectively. The aim of the present research was to improve its oral bioavailability, in particular by preventing intestinal degradation and enhancing membrane permeation. In stomach, P% of BN used alone, BN+borneol, BN+SDS were 4.51, 7.86 and 8.09%, respectively. In intestine, lecithin, F-68, and SDS were proved to be effective absorption promoters when CP was used as stabilizer.In order to achieve more reliable conclusion, in vivo experiment was conducted. First, RP-HPLC method was developed for the determination of BN in rat plasma using a mobile phase consisting of methanol-water (20:80, v/v, pH 2.50) and detected at 275nm. The results showed that Cmax of BN used alone and co-administerded with CP+borneol were 0.44μg·ml-1 and 2.42μg·ml-1, respectively, F was increased from 4.83% to 12.78%. When co-administerded with CP+ lecithin, F of BN was increased to 8.27%, but Cmax exhibited no significant change. It indicated that borneol and lecithin could improve oral bioavailability of BN.Based on the research of physicochemical properties, the absorption mechanism and influence factor of BN, absorption promoters and stabilizer were invstigated. These results will be of significance for the development and research of new drug delivery systems of BN.
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