Simultaneous LC-MS/MS Determination of Danshensu and Paeoniflorin for Permeability Studies in Caco-2 Intestinal Absorption Model

A high sensitive method based on liquid chromatography tandem mass spectrometry(LC-MS/MS) was developed and validated for the study of permeability of danshcnsu(DS) and paeoniflorin(PF) in Caco-2 intestinal absorption model. The DS and PF were extracted from cell culture by vacuum-lyophilizing and then separated on a Zorbax Stable Bond C18 column with 0.1% acetic acid aqueous solution and methanol as mobile phase. Detection was carried out by negative elcctrospray ionization(ESI−) with selected reaction monitoring(SRM) mode. The apparent permeability cocfficicnts(Papp) of DS and PF in Caco-2 cell medium were calculated and the effects of verapamil on the coefficients Papp of the two test compounds were also illustrated. The permeability of PF was much better than that of DS when the two compounds were administrated individually. Co-administration of DS and PF led to the decrease of the transport from apical side to basolateral side for both the compounds. However, the transport in the contrary direction were accelerated. It was also observed that verapamil could accelerate the transport of the test compounds from apical side to basolateral side. However, the absorption-enhanced effect of verapamil was attenuated when DS and PF were co-administrated. These observations suggest that both passive diffusion and active efflux involved in P-gp would effect the passage of DS and PF across Caco-2 cell monolayer. At the same time, the co-administration of DS and PF to an alteration of transport behavior, which suggests that the interaction must be taken into account when 'n-in-one' samples were used in Caco-2 intestinal model.