The purpose of this study was to study the absorption characteristics of eight main components from dragon's blood phenolic extracts in Caco-2 cells based on the humancolon cancer cell Caco-2 model, and to clarify the oral absorption mechanism of such phenolic extracts. UPLC-MS/MS was used in this study to determine the content of 8 active ingredients including thevetiaflavone, 7,4'-dihydroxyflavone, 7,4'-dihydroxy-5-methoxyhomoisoflavanone, 7,4'-dihydroxyhomoisoflavanone, loureirin C, loureirin A, loureirin B and pterostilbene from dragon's blood phenolic extracts, and Caco-2 cells were used to investigate the effects of incubation time, concentration, temperature, P-gp inhibitor, MRP inhibitor, OCTN1 inhibitor and OCTN2 inhibitor on the absorption of each component. In addition, the transport experiment was conducted to measure the apparent permeability coefficient P_(app) and transport rate of the eight main components to predict the oral absorption mechanism of dragon's blood phenolic extracts. The experimental results showed that the cell uptake of the eight main components in dragon's blood phenolic extracts was time-dependent and concentration dependent, and the uptake of each component did not need to consume energy, which was consistent with the passive diffusion process. P-gp inhibitor, MRP inhibitor and OCTN1 inhibitor had no effect on the cell uptake of each component, only the addition of OCTN2 inhibitor significantly reduced the uptake of pterostilbene(P<0.05). In the transport results, the ER values of the outflow rates of the eight components were all less than 1.5. The above results show that the absorption mechanism of the eight components in Draconis resina phenolic extract may be passive diffusion, and pterostilbene may be the substrate of OCTN2.
Keywords: Caco-2 model; UPLC-MS/MS; dragon′s blood phenolic extracts; passive diffusion; uptake.