代谢
精神活性β-咔啉生物碱,对5-羟色胺、多巴胺、苯二氮卓和咪唑啉受体具有高亲和力,并能刺激蓝斑神经元的兴奋,是通过色氨酸衍生的吲哚烷胺与醛类通过皮克特-斯彭格勒缩合在植物和哺乳动物体内形成的。细胞色素P450 1A1(18.5)、1A2(20)和2D6(100)催化了哈马林的去甲基化,而CYP1A1(98.5)、CYP1A2(35)、CYP2C9(16)、CYP2C19(30)和CYP2D6(115)催化了哈明的去甲基化(相对活性)。哈马林到哈明的脱氢/芳香化反应不是由芳香化酶(CYP19)、CYP1A2、CYP2C9、CYP2D6、CYP3A4、重组细胞色素P450混合物或人肝微体(HLMs)进行的。计算了每种同工酶和混合HLMs介导的去甲基化的动力学参数。哈马林的K(cat)(min(-1))和Ku(uM)值分别为:CYP1A1,10.8和11.8;CYP1A2,12.3和13.3;CYP2C9,5.3和175;CYP2C19,10.3和160;CYP2D6,39.9和1.4。哈明的值分别为:CYP1A1,45.2和52.2;CYP1A2,9.2和14.7;CYP2C9,11.9和117;CYP2C19,21.4和121;CYP2D6,29.7和7.4。使用单克隆抗体的抑制研究证实,CYP1A2和CYP2D6是混合HLMs中哈马林(分别占20%和50%)和哈明(分别占20%和30%)去甲基化的主要同工酶。CYP2D6的转化数是迄今为止报告的CYP2D6底物中最高的。最后,与野生型小鼠相比,CYP2D6转基因小鼠的哈马林和哈明O-脱甲基酶活性增加。这些发现表明,多态性CYP2D6在哈明和哈马林的药理学和毒理学中发挥作用。
The psychotropic beta-carboline alkaloids, showing high affinity for 5-hydroxytryptamine, dopamine, benzodiazepine, and imidazoline receptors and the stimulation of locus coeruleus neurons, are formed endogenously from tryptophan-derived indolealkylamines through the Pictet-Spengler condensation with aldehydes in both plants and mammals. Cytochromes P450 1A1 (18.5), 1A2 (20), and 2D6 (100) catalyzed the O-demethylation of harmaline, and CYP1A1 (98.5), CYP1A2 (35), CYP2C9 (16), CYP2C19 (30), and CYP2D6 (115) catalyzed that of harmine (relative activities). The dehydrogenation/aromatization of harmaline to harmine was not carried out by aromatase (CYP19), CYP1A2, CYP2C9, CYP2D6, CYP3A4, pooled recombinant cytochromes P450, or human liver microsomes (HLMs). Kinetic parameters were calculated for the O-demethylations mediated by each isozyme and by pooled HLMs. K(cat) (min(-1)) and Ku (uM) values for harmaline were: CYP1A1, 10.8 and 11.8; CYP1A2, 12.3 and 13.3; CYP2C9, 5.3 and 175; CYP2C19, 10.3 and 160; and CYP2D6, 39.9 and 1.4. Values for harmine were: CYP1A1, 45.2 and 52.2; CYP1A2, 9.2 and 14.7; CYP2C9, 11.9 and 117; CYP2C19, 21.4 and 121; and CYP2D6, 29.7 and 7.4. Inhibition studies using monoclonal antibodies confirmed that CYP1A2 and CYP2D6 were the major isozymes contributing to both harmaline (20% and 50%, respectively) and harmine (20% and 30%) O-demethylations in pooled HLMs. The turnover numbers for CYP2D6 are among the highest ever reported for a CYP2D6 substrate. Finally, CYP2D6-transgenic mice were found to have increased harmaline and harmine O-demethylase activities as compared with wild-type mice. These findings suggest a role for polymorphic CYP2D6 in the pharmacology and toxicology of harmine and harmaline.
来源:Hazardous Substances Data Bank (HSDB)