Evaluation of benzyltetrahydroisoquinolines as ligands for neuronal nicotinic acetylcholine receptors
作者:Richard Exley、Patricio Iturriaga-Vásquez、Ronald J Lukas、Emanuele Sher、Bruce K Cassels、Isabel Bermudez
DOI:10.1038/sj.bjp.0706307
日期:2005.9
Effects of derivatives of coclaurine (C), which mimic the ‘eastern’ or the nonquaternary halves of the alkaloids tetrandrine or d‐tubocurarine, respectively, both of which are inhibitors of nicotinic acetylcholine receptors (nACh), were examined on recombinant, human α7, α4β2 and α4β4 nACh receptors expressed in Xenopus oocytes and clonal cell lines using two‐electrode voltage clamping and radioligand binding techniques.
In this limited series, Cs have higher affinity and are most potent at α4 subunit‐containing‐nACh receptors and least potent at homomeric α7 receptors, and this trend is very marked for the N‐unsubstituted C and its O,O′‐bisbenzyl derivative.
7‐O‐Benzyl‐N‐methylcoclaurine (BBCM) and its 12‐O‐methyl derivative showed the highest affinities and potencies at all three receptor subtypes, and this suggests that lipophilicity at C7 and/or C12 increases potency.
Laudanosine and armepavine (A) were noncompetitive and voltage‐dependent inhibitors of α7, α4β2 or α4β4 receptors, but the bulkier C7‐benzylated 7BNMC (7‐O‐benzyl‐N‐methylcoclaurine) and 7B12MNMC (7‐O‐benzyl‐N,12‐O‐dimethyl coclaurine) were voltage‐independent, noncompetitive inhibitors of nACh receptors. Voltage‐dependence was also lost on going from A to its N‐ethyl analogue.
These studies suggest that C derivatives may be useful tools for studies characterising the antagonist and ion channel sites on human α7, α4β2 or α4β4 nACh receptors and for revealing structure–function relationships for nACh receptor antagonists.
British Journal of Pharmacology (2005) 146, 15–24. doi:10.1038/sj.bjp.0706307
考察了 **酒花碱(C)的衍生物**(分别模拟了四氢protoberberine生物碱——四氢protoberberine *或 d-筒箭毒碱的“东方”部分或非季铵部分)对表达于非洲爪蟾卵母细胞和克隆细胞系中的重组人 **α7、α4β2 和 α4β4型烟碱乙酰胆碱受体(nAChR)**的作用。这些衍生物使用双电极电压钳制技术(two-electrode voltage clamping)和放射配体结合技术进行了体外研究。值得注意的是,这些化合物均为 **nAChR抑制剂**。
在本研究中,**Cs(酒花碱的衍生物)在 α4 亚基依赖型 nAChR 上展现了最高的亲和力和效力,而在同源 α7 受体上的效力最为弱。**这一趋势在 **N-未取代的 C(酒花碱)及其 O,O'-双苯甲基衍生物**中表现得尤为明显。
其中,**7-O-苯甲基-N-甲基酒花碱(BBCM)及其 12-O-甲基衍生物**在所有三种受体亚型(α7、α4β2 和 α4β4)上均展现了最高的亲和力和效力,表明 **C7 和/或 C12 位上的疏水性增加显著提升了活性**。
此外,**甲基丙二胺(Laudanosine)和 B Nedergaard 碱(armepavine,A)**被发现为 **α7、α4β2 或 α4β4 受体的非竞争性和电压依赖性抑制剂。**然而,**体积更大的 C7-苯甲基化衍生物(如 7BNMC 和 7B12MNMC)**则表现为 **电压独立的非竞争性 nAChR 抑制剂。**值得注意的是,**与 A 相比,其 N-乙基类似物也失去了电压依赖性。**
这些研究结果表明,**C 衍生物可能成为研究人 α7、α4β2 或 α4β4 型烟碱乙酰胆碱受体拮抗剂和离子通道位点特征的有用工具,**并且有助于揭示 **烟碱乙酰胆碱受体拮抗剂的结构-功能关系。**
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出处:
*British Journal of Pharmacology* (2005), **146**(1), 15–24.
DOI: [10.1038/sj.bjp.0706307](https://doi.org/10.1038/sj.bjp.0706307)