代谢
甲氧基苯(MDBs)和结构相关的烯基苯被比较了它们在预防四氯化碳(CCl4)引起的小鼠肝脏坏死的有效性。用异黄樟素、黄樟素、二氢黄樟素和苯并二氧杂环戊烷在剂量低至10 mg/kg的情况下预处理,显著预防了血浆转氨酶水平的升高和与CCl4诱导的肝脏坏死相关的组织化学变化,而胡椒基丁氧化物(PBO)、丁香酚、异丁香酚、芝麻酚和姜黄素即使在200 mg/kg的剂量下也不能预防CCl4的肝毒性。然而,如果毒物给药后10分钟内给予异黄樟素,其仅部分具有肝保护作用。在异黄樟素给药后1小时分离的肝脏微粒体中CYP2E1活性显著降低,而PBO给药后则没有。异黄樟素、黄樟素、二氢黄樟素和苯并二氧杂环戊烷在体外也比丁香酚和异丁香酚更有效地抑制CYP2E1依赖的代谢,而PBO并不抑制CYP2E1活性。因此,异黄樟素、黄樟素和苯并二氧杂环戊烷的保护作用主要归因于它们能够使CYP2E1失活,CYP2E1是参与CCl4生物活化的主要同工酶。在CYP2E1诱导的小鼠中,CCl4肝毒性的显著增强也被异黄樟素而非PBO预处理完全预防,支持异黄樟素通过抑制CYP2E1对其对CCl4的肝保护作用有所贡献的假设。异黄樟素和黄樟素还预防了溴三氯甲烷(BrCCl3)诱导的肝细胞毒性,而PBO则无效。
Methylenedioxybenzenes (MDBs) and structurally related alkenylbenzenes were compared for their effectiveness in preventing carbon tetrachloride (CCl4)-induced liver necrosis in mice. Pretreatment with isosafrole, safrole, dihydrosafrole, and benzodioxole at dosages as low as 10 mg/kg significantly prevented the increase in plasma transaminase levels and histochemical changes associated with CCl4-induced liver necrosis, whereas piperonyl butoxide (PBO), eugenol, isoeugenol, sesamol, and curcumin did not prevent CCl4 hepatotoxicity even at 200 mg/kg. However, isosafrole was only partly hepatoprotective if administered 10 min after the toxicant. Liver microsomes isolated 1 hr after isosafrole but not after PBO administration had a markedly decreased CYP2E1 activity. Isosafrole, safrole, dihydrosafrole, and benzodioxole in vitro also inhibited CYP2E1-dependent metabolism more effectively than eugenol and isoeugenol, whereas PBO did not inhibit CYP2E1 activity. The protective effects of isosafrole, safrole, and benzodioxole were therefore predominantly attributed to their ability to inactivate CYP2E1, the major isozyme involved in CCl4 bioactivation. The marked potentiation of CCl4 hepatotoxicity in CYP2E1-induced mice was also completely prevented by isosafrole but not PBO pretreatment, supporting the hypothesis that CYP2E1 inhibition by isosafrole contributes to its hepatoprotective effect against CCl4. Isosafrole and safrole also prevented bromotrichloromethane (BrCCl3)-induced hepatocyte cytotoxicity, whereas PBO was ineffective.
来源:Hazardous Substances Data Bank (HSDB)