Absorption properties and mechanism of trolline and veratric acid and their implication to an evaluation of the effective components of the flowers of Trollius chinensis

AIM:To study the absorption properties and mechanism of two important components,trolline and veratric acid,from the flowers of Trollius chinensis,in order to better understand the contribution of these two compounds to the effectiveness of these flowers.METHOD:The human Caco-2 cell monolayer model was employed to study the transport of trolline and veratric acid from apical side(AP) to basal side(BL),and from BL to AP by determining the transport rates as the function of time and concentration and calculating apparent permeability coefficients(Papp).RESULTS:Trolline and veratric acid were transported across Caco-2 cell monolayer through different mechanisms in a concentration dependent manner.Trolline was transported at a Papp level of 10-6 cm·s-1 with a Papp AP→BL/Papp BL→AP ratio of more than 1.8 or less than 0.8,while veratric acid was transported at a Papp level of 10-5 cm·s-1 with a Papp AP→BL/Papp BL→AP ratio of close to 1.0.CONCLUSION:Trolline is moderately absorbed through an associative mechanism involving active and passive transport,and veratric acid is well-absorbed mainly through passive diffusion.These factors should be taken into account when chemically assessing the pharmacodynamic material basis of the flowers of T.chinensis.