In vivo intestinal absorption characteristics of α-hederin in rats Transport characteristics of hydroxysafflor yellow A across Caco-2 cell monolayer model Absorption mechamism of dehydroandrographolide in human Caco-2 cell monolayer model Absorption mechamism of dehydroandrographolide in human Caco-2 cell monolayer model Absorption characteristics of 5 components of Xinshao extract in Caco-2 cells