Study on the absorption of corosolic acid in the gastrointestinal tract and its metabolites in rats

Corosolic acid (CRA) has been widely used as a food supplement. However, its pharmacokinetic behavior still needs to be explored. In this study, the absorption of CRA in stomach and intestine were investigated by in situ gastric absorption and in situ single-pass perfusion, respectively. Furthermore, the metabolites of CRA in rat plasma, bile, and urine were identified by UPLC-QTOF-MS. The enzymes responsible for its metabolism were explored by rat liver microsome (RLMs). The effects of plasma containing metabolites on cancer cell growth and glucose consumption were evaluated by HT29 and HepG2 cells receptively. The results showed that CRA absorption rate is approximately 20% to 40% in stomach. It has similar absorption rate constant (Ka) in duodenum/jejunum/ileum/colon. However, its effective permeability (P-eff) in ileum at 9 mu g/mL is significantly higher than the P-eff in colon. Moreover, five possible metabolites were identified in plasma and bile, suggesting CRA could be metabolized through methyl carboxylation, hydroxylation, methyl aldehyde substitution, glucuronidation, and acetylation in vivo. Meanwhile, CYP1A2 and CYP3A4 were found to participate in its metabolism. The plasma containing metabolites of CRA significantly inhibited the growth of HT29 colon cancer cells and stimulated glucose consumption of HepG2 cells. Taken together, these results demonstrated that CRA has good absorption in both stomach and small intestine, but it could be metabolized partly due to CYP1A2 and CYP3A4 in vivo. Its metabolites might be responsible for the excellent anti-cancer and anti-diabetes activities of CRA. This study will provide evidence for further CRA development.