Comparison of intestinal absorption characteristics between rhubarb traditional Chinese medicine preparation and activity ingredients using in situ and in vitro model

Objective: The intestinal absorption characteristics of active ingredients are very important for oral administration of traditional Chinese medicine(TCM) to achieve the desired therapeutic effect.However, a deeper understanding about active ingredients absorption characteristics is still lack. The aim of this study was to investigate the absorption properties and mechanism of rhubarb active ingredients in TCM preparation and pure form.Methods: The intestinal absorption behavior of active ingredients in Shenkang extract(SKE) and rhubarb anthraquinone ingredients(RAI) were investigated by in situ single-pass intestinal perfusion model. And the bidirectional transport characteristics of these active ingredients were assessed by in vitro Caco-2 cell monolayer model.Results: In situ experiment on Sprague-Dawley rats, the effective permeability coefficient values of aloeemodin, emodin and chrysophanol in RAI were higher than those in SKE, and the value of rhein in RAI was lower than that in SKE. But the easily absorbed segments of intestine were consistent for all ingredients,whether in SKE or in RAI. In vitro experiment, the apparent permeability coefficient values of rhein, emodin and chrysophanol in RAI were higher than those in SKE, and this value of aloe-emodin in RAI was lower than that in SKE. But their efflux ratio(ER) values in SKE and RAI were all similar.Conclusion: Four rhubarb anthraquinone ingredients in SKE and RAI have similar absorption mechanism and different absorption behavior, and the microenvironment of the study models influenced their absorption behavior. The results may provide an aid for understanding of the absorption characteristics of the TCM active ingredients in complex environments and the complementarities of different research models.