甘草提取物及其主要成分对Caco-2细胞膜上P-gp功能和表达的影响

 目的 初步考察甘草提取物及其主要成分（甘草甜素、甘草次酸和甘草苷）对Caco-2细胞膜上P-糖蛋白（P-gp）功能和表达的影响，以备进一步探讨甘草新的解毒机制。方法 利用流式细胞术检测Caco-2细胞内罗丹明123（Rho-123）的荧光强度和细胞膜上P-gp的表达，以考察P-gp外排功能和表达水平的变化。结果 经过60 min的干预，甘草提取物(1， 10， 100 μg·mL-1)、甘草甜素(1， 10， 100 μg·mL-1)和甘草苷(1， 10， 100 μg·mL-1)Caco-2细胞内Rho-123的荧光强度较阴性对照组分别降低了34.66%、28.90%、24.56%、27.89%、26.29%、37.33%、19.51%、21.86%和19.03%（P＜0.05）。经过72 h的干预，甘草提取物中质量浓度(10 μg·mL-1)组，甘草甜素低、中、高质量浓度(1， 10， 100 μg·mL-1)组，甘草次酸中、高质量浓度(1， 10 μg·mL-1)组Caco-2细胞膜上P-gp表达的阳性率较阴性组分别增加了31.18%、61.67%、70.32%、77.43%、37.58%和49.14%（P＜0.05）。结论 甘草提取物、甘草甜素和甘草苷可能增强Caco-2细胞膜上P-gp的功能，而中质量浓度的甘草提取物，低、中、高质量浓度的甘草甜素和中、高质量浓度的甘草次酸则可能上调P-gp的表达。甘草甜素既能增强Caco-2细胞膜上P-gp的功能，又能上调其表达，可能是甘草影响P-gp的有效成分。

Effects of Radix Glycyrrhiza and Its Main Components on the Function and Expression of P-glycoprotein in Caco-2 Cells

OBJECTIVE To determine the effects of radix glycyrrhiza and its main components (glycyrrchizin， glycyrrhetinic acid and liquiritin) on the function and expression of P-glycoprotein in Caco-2 cell monolayers. METHODS The flow cytometry was used to detect the expression level of P-glycoprotein and the fluorescence intensity of rhodamine 123， the later showed the efflux function of P-glycoprotein. RESULTS The uptake of rhodamine 123 in Caco-2 cells was significantly decreased by 34.66%，28.90%，24.56%，27.89%，26.29%，37.33%，19.51%，21.86% and 19.03%， respectively after the concomitant of radix glycyrrhiza， glycyrrchizin and liquiritin with the low， middle and high concentration (1， 10 and 100 μg·mL-1) for 60 min co-incubation. The positive rate of P-glycoprotein in Caco-2 cells were significantly increased by 31.18%， 61.67%， 70.32%， 77.43%， 37.58% and 49.14% after the concomitant of radix glycyrrhiza (10 μg·mL-1)， glycyrrchizin (1， 10， 100 μg·mL-1)， glycyrrhetinic acid (1， 10 μg·mL-1) for 72 h co-incubation. CONCLUSION Radix glycyrrhiza， glycyrrchizin and liquiritin may induce the efflux of rhodamine 123 mediated by P-glycoprotein in Caco-2 cells. Secondly， radix glycyrrhiza (10 μg·mL-1)， glycyrrchizin (1， 10， 100 μg·mL-1) and glycyrrhetinic acid(1， 10 μg·mL-1) could up-regulate the expression levels of P-glycoprotein in Caco-2 cells. As glycyrrchizin induced the function and up-regulate the expression level of P-glycoprotein in Caco-2 cells， it might be the effective constituent of radix glycyrrhiza.