Absorption and transport mechanism of ursolic acid across Caco-2 monolayer model

Objective To study the absorption and transport mechanism of ursolic acid(UA) by using Caco-2 monolayer model.Methods Evaluating the transport characteristic through studying whether P-glycoprotein(P-gp) transporter inhibitor Verapamil(VER) exists or not by using Caco-2 cell monolayer as an intestinal epithelial cell model and investigating the effects of uptake time,drug concentration,system temperature,and pH value of culture media on the uptake of UA.The drug concentration was measured by HPLC coupled with UV detector.Transport parameters and apparent permeability coefficients (P_(app)) were then calculated.Results In the concentration range of 10—40μmol/L,the uptake of UA by Caco-2 cell all linearly increased.The P_(app) of UA transported on Caco-2 cell monolayer model significantly changed when the specificity inhibitory of P-gp was added to model and the apparent permeability ratio decreased from 3.445 to 1.386.Conclusion The intestinal absorption of UA is passive diffusion as the dominating process and active transportation mediated by P-gp transporter in Caco-2 cell monolayer model.