野黄芩苷和野黄芩素在Caco-2细胞模型中的吸收转运特性

Absorption and transportation characteristics of scutellarin and scutellarein across Caco-2 monolayer model

目的:研究黄酮类化合物野黄芩苷(scutellarin)和野黄芩素(scutellarein)在Caco-2单层细胞模型中的吸收和转运特性。考察缓冲液、作用时间、P-糖蛋白(P-glycoprotein,P-gp)抑制剂、多药耐药蛋白2(multidrug resistance protein 2,MRP2)抑制剂、乳腺癌耐药蛋白(breast cancer drug resistance protein,BCRP)抑制剂对野黄芩苷和野黄芩素吸收转运的影响。方法:利用Caco-2单层模型研究从绒毛面(apical,AP)侧到基底面(basolateral,BL)侧以及从BL侧到AP侧两个方向的转运过程。应用高效液相色谱法定量分析,计算转运参数和表观渗透系数(apparent permeability coefficient,Papp)。结果:两化合物在磷酸盐缓冲液和Hanks缓冲液中的Papp有差异。在磷酸盐缓冲液中野黄芩苷AP→BL侧无转运,BL→AP侧的Papp为(0.74～1.58)×10-6cm/s;野黄芩素在AP→BL侧与BL→AP侧的Papp分别为(4.33～6.79)×10-6cm/s和(1.32～2.56)×10-6cm/s。随着时间延长,Papp逐渐下降,野黄芩素的吸收转运优于野黄芩苷。P-gp抑制剂维拉帕米、MRP2抑制剂MK-571钠盐及BCRP抑制剂利血平能够促进野黄芩苷的吸收转运,维拉帕米能促进野黄芩素的吸收转运,MK-571钠盐促进野黄芩素外排。结论:野黄芩苷属于难吸收的化合物,野黄芩素吸收优于野黄芩苷,野黄芩素可通过小肠上皮被动吸收进入体内。P-gp抑制剂能够促进野黄芩苷和野黄芩素的转运,MRP2抑制剂和BCRP抑制剂能够促进野黄芩苷的转运,MRP2抑制剂促进野黄芩素外排。野黄芩苷吸收不良和外排蛋白的作用是造成其生物利用度较低的原因。

Objective:To investigate the absorption and transepithelial transport characteristics of scutellarin and scutellarein in the human colonic adenocarcinoma cell (Caco-2) monolayer model. The influence factors on these two compounds’ absorption were investigated,such as buffer solution,duration of culture,and inhibitors of multidrug resistance-associated protein 2 (MRP2),breast cancer drug resistance protein (BCRP) and P-glycoprotein (P-gp).Methods:By using Caco-2 monolayer as an intestinal epithelial cell model,the transport process was studied from apical (AP) side to basolateral (BL) side or from BL to AP. The two compounds were determined by high-performance liquid chromatography coupled with diode-array-detector detection. Transport parameters and apparent permeability coeffients (Papp) were calculated.Results:The Papp values of scutellarin and scutellarein were different in two buffer solutions,respectively. In phosphate buffered saline,scutellarin had no absorption from AP to BL,while its Papp value was 0.74×10-6 to 1.58×10-6 cm/s from BL to AP. The Papp values of scutellarein were 4.33×10-6 to 6.79×10-6 cm/s and 1.32×10-6 to 2.56×10-6 cm/s from AP to BL and from BL to AP,respectively. The Papp value gradually decreased with time. The absorption of scutellarein was better than that of scutellarin. The scutellarin absorption was improved by verapamil,MK-571 and reserpine. The scutellarein absorption was improved by verapamil whereas its excretion was improved by MK-571.Conclusion:Absorption of scutellarin is difficult in Caco-2 monolayer cells,which contributes to its low bioavailability. Scutellarein absorption is better than scutellarin absorption. Scutellarein transepithelial transport is passive diffusion. The inhibitor of P-gp can improve scutellarin and scutellarein transportation. The inhibitors of MRP2 and BCRP can promote transportation of scutellarin. The inhibitor of MRP2 can promote efflux of scutellarein. The multidrug resistance-associated protein may be the second reason for low bioavailability of scutellarin.