mPEG-PLGA聚合物对大鼠肝脏CYP450酶活性的影响

目的：研究mPEG-PLGA聚合物对大鼠肝CYP450酶活性的影响。方法：采用芘荧光探针技术测定mPEG-PLGA聚合物的临界胶束浓度（CMC），并用薄膜分散法制备mPEG-PLGA聚合物胶束；分别采用大鼠肝微粒体和原代大鼠肝细胞模型，将mPEG-PLGA聚合物溶液与CYP450酶特异性探针底物孵育，经液-质联用技术（LC-MS/MS）检测代谢产物，通过比较代谢产物生成量的变化，评价聚合物对CYP450酶的抑制和诱导作用。结果：mPEG-PLGA聚合物的CMC为5.37 μg·mL^-1；mPEG-PLGA聚合物浓度低于CMC时对大鼠肝CYP450酶无抑制作用；当聚合物胶束质量浓度≥100 μg·mL^-1时显示有抑制作用，且呈现浓度依赖性。mPEG-PLGA聚合物对CYP1A1/B2、CYP1A2、CYP2B1、CYP2C6、CYP2C11、CYP2D2、CYP3A1/2（底物为咪达唑仑）、CYP3A1/2（底物为睾酮）7种酶亚型的IC₅₀值分别为1.13，2.37，2.38，1.77，1.32，1.17，1.12，0.91 mg·mL^-1，其中对CYP3A1/2的抑制作用最为明显。mPEG-PLGA聚合物在0.1~1 000 μg·mL^-1质量浓度范围对CYP1A2酶均有诱导作用，且在高质量浓度1 000 μg·mL^-1时最强（P<0.001）；而该聚合物仅在0.1 μg·mL^-1时对CYP2B1、CYP2C6和CYP3A1/2酶呈现诱导作用（P<0.05）。结论：mPEG-PLGA聚合物对大鼠肝脏CYP450酶亚型活性有一定的抑制和诱导作用，其抑制和诱导作用程度与酶亚型种类和聚合物浓度有关。

Effects of mPEG-PLGA polymer on activity of rat CYP450 isozymes in vitro

OBJECTIVE To study effects of mPEG-PLGA polymer on activity of rat CYP450 isozymes in vitro. METHODS Critical micelle concentration (CMC) of mPEG-PLGA polymer was determined by fluorescence probe technique with pyrene. Micelles were prepared by thin film hydration method. mPEG-PLGA polymer was incubated at a series of concentration levels with specific probe substrates of CYP450 isozymes in both rat liver microsomes and primary hepatocytes. Inhibitory and inductive effects of mPEG-PLGA polymer on activity of CYP450 isozymes were evaluated by analyzing metabolites using a robust liquid mass spectrometry (LC-MS/MS) assay. RESULTS CMC value of mPEG-PLGA polymer was 5.37 μg·mL^-1. When mPEG-PLGA polymer concentrations were ≥100 μg·mL^-1, significant inhibitory effects were produced on CYP450 enzymes in a concentration-dependent manner. However, no change was observed below CMC. IC₅₀ values of mPEG-PLGA polymer on seven isozymes (CYP1A1/B2, CYP1A2, CYP2B1, CYP2C6, CYP2C11, CYP2D2, CYP3A1/2) were 1.13, 2.37, 2.38, 1.77, 1.32, 1.17, 1.12 (substrate for midazolam), 0.91(substrate for testosterone) mg·mL^-1, respectively, with strongest inhibition observed on CYP3A1/2. The mPEG-PLGA polymer showed obvious induction on CYP1A2, especially at the highest concentration (1000 μg·mL^-1) (P<0.001), while activities of CYP2B1, CYP2C6 and CYP3A1/2 enzymes were increased when concentration of mPEG-PLGA polymer was 0.1 μg·mL^-1 (P<0.05). CONCLUSION mPEG-PLGA polymer plays a certain role in both inhibition and induction of rat CYP450 isozymes activity, based on types of isozymes and concentrations of polymer.