Department of Pharmaceutical Technology, University of Innsbruck, Innrain, Innsbruck, Austria.
Eur J Pharm Biopharm. 2011 Aug;78(3):361-5. doi: 10.1016/j.ejpb.2011.02.017. Epub 2011 Mar 6.
The aim of the present study was to investigate the potential of different thiolated polymers (thiomers) on the catalytic activity of CYP450s on one hand and to explore new inhibitors for CYP activity on the other hand. Several thiolated polymers including poly(acrylic acid)-cysteine (PAA-cysteine), chitosan-thioglycolic acid (chitosan-TGA), and thiolated PEG-g-PEI copolymer along with brij 35, myrj 52 and the well-established CYPP450 inhibitor verapamil were screened for their CYP3A4 and CYP2A6 inhibitory activity, and their IC(50) values were determined. Both enzyme inhibition assays were performed in 96-well microtiter plates. 7-Benzyloxy-4-(trifluoromethyl)-coumarin (BFC) and 7-hydroxycoumarin (7-HC) were used as fluorescent substrates in order to determine CYP3A4 and CYP2A6 catalytic activity, respectively. All investigated compounds inhibited CYP3A4 as well as CYP2A6 activity. All tested (thiolated) polymers were found to be more potent inhibitors of CYP3A4 than of CYP2A6 catalytic activity. Apart from verapamil that is a known CYP3A4 inhibitor, brij 35 and myrj 52 were explored as potent inhibitors of CYP3A4 and CYP2A6 catalytic activity. Among the tested polymers, the rank order for CYP3A4 inhibition was PAA-cysteine (100 kDa)>brij 35>thiolated PEG-g-PEI copolymer (16 kDa)>myrj 52>PAA (100 kDa)>PAA-cysteine (450 kDa)>verapamil>PAA (450 kDa)>chitosan-TGA (150 kDa)>chitosan (150 kDa). On the other hand, the rank order of CYP2A6 inhibition was brij 35>PAA-cysteine (100kDa)>chitosan-TGA (150 kDa)>PAA (100 kDa)>thiolated PEG-g-PEI copolymer (16 kDa)>PAA-cysteine (450 kDa)>chitosan (150 kDa)>verapamil>PAA (450 kDa)>myrj 52. Thus, this study suggests that (thiolated) polymers display a promising potential to inhibit cytochrome P450s activity and might turn out to be potentially valuable tools for improving the oral bioavailability of actively secreted compounds by avoiding intestinal metabolism.
本研究旨在一方面考察不同巯基化聚合物（硫醇）对 CYP450 酶催化活性的潜在影响，另一方面探索新的 CYP 活性抑制剂。几种巯基化聚合物，包括聚（丙烯酸）-半胱氨酸（PAA-半胱氨酸）、壳聚糖-硫代乙醇酸（壳聚糖-TGA）和巯基化 PEG-g-PEI 共聚物，以及 Brij 35、Myrj 52 和经证实的 CYP450 抑制剂维拉帕米，被筛选用于其 CYP3A4 和 CYP2A6 抑制活性，并测定其 IC50 值。两种酶抑制测定均在 96 孔微量滴定板中进行。7-苄氧基-4-（三氟甲基）-香豆素（BFC）和 7-羟基香豆素（7-HC）分别用作荧光底物，以分别确定 CYP3A4 和 CYP2A6 的催化活性。所有研究的化合物均抑制 CYP3A4 和 CYP2A6 活性。所有测试的（巯基化）聚合物均被发现比 CYP2A6 催化活性对 CYP3A4 更有效。除了已知的 CYP3A4 抑制剂维拉帕米外，Brij 35 和 Myrj 52 也被探索为 CYP3A4 和 CYP2A6 催化活性的有效抑制剂。在所测试的聚合物中，CYP3A4 抑制的等级顺序为 PAA-半胱氨酸（100 kDa）>Brij 35>巯基化 PEG-g-PEI 共聚物（16 kDa）>Myrj 52>PAA（100 kDa）>PAA-半胱氨酸（450 kDa）>维拉帕米>PAA（450 kDa）>壳聚糖-TGA（150 kDa）>壳聚糖（150 kDa）。另一方面，CYP2A6 抑制的等级顺序为 Brij 35>PAA-半胱氨酸（100 kDa）>壳聚糖-TGA（150 kDa）>PAA（100 kDa）>巯基化 PEG-g-PEI 共聚物（16 kDa）>PAA-半胱氨酸（450 kDa）>壳聚糖（150 kDa）>维拉帕米>PAA（450 kDa）>Myrj 52。因此，本研究表明（巯基化）聚合物显示出抑制细胞色素 P450 酶活性的有前途的潜力，并可能成为通过避免肠道代谢来提高主动分泌化合物口服生物利用度的潜在有价值工具。
