Latli B, Tomizawa M, Casida J E
Department of Environmental Science, Policy, and Management, University of California, Berkeley 94720-3112, USA.
Bioconjug Chem. 1997 Jan-Feb;8(1):7-14. doi: 10.1021/bc960066c.
The insect nicotinic acetylcholine receptor (nAChR) is the target for the major insecticide imidacloprid (IMI) and for the first candidate photoaffinity probe described here. Addition to 1-[(6-chloro-3-pyridinyl) methyl]-4,5-dihydro-2-nitromethylene-1H-imidazolidine (the nitromethylene analog of the nitroimine IMI) of formaldehyde and any one of several primary amines is known to give hexahydro-8-nitroimidazo[1,2-c]pyrimidine derivatives. These imidazopyrimidines with a wide range of N-substituents were found to inhibit [3H]IMI binding to the Drosophila or Musca nAChR by 50% (IC50) at 0.7-38 nM. Esterification of the N-(2-hydroxyethyl) derivative with 2-azido-5-(trimethylstannyl)-benzoic acid and then iododestannylation using Na125I and chloramine-T provide the candidate photoaffinity probe 6-[2-(2-azido-5-[125I]iodobenzoyl) ethyl]-1-[(6-chloro-3-pyridinyl)methyl]-1,2,3,5,6,7-hexahydro-8 -nitroimidazo[1,2-c]pyrimidine. This compound (unlabeled) has an IC50 of 8 nM for [3H]-IMI binding in Drosophila head membranes, and the 125I-labeled photoaffinity probe labels only a 66 kDa protein(s) at a specific site inhibited by (-)-nicotine, consistent with the insecticide-binding subunit of the nAChR.
昆虫烟碱型乙酰胆碱受体（nAChR）是主要杀虫剂吡虫啉（IMI）以及本文所述的首个候选光亲和探针的作用靶点。已知向1-[(6-氯-3-吡啶基)甲基]-4,5-二氢-2-硝基亚甲基-1H-咪唑烷（硝基亚胺IMI的硝基亚甲基类似物）中加入甲醛和几种伯胺中的任何一种，会生成六氢-8-硝基咪唑并[1,2-c]嘧啶衍生物。发现这些具有广泛N-取代基的咪唑嘧啶在0.7 - 38 nM浓度下可使[3H]IMI与果蝇或家蝇nAChR的结合抑制50%（IC50）。将N-(2-羟乙基)衍生物与2-叠氮基-5-(三甲基锡基)苯甲酸进行酯化反应，然后使用Na125I和氯胺-T进行脱锡碘化反应，得到候选光亲和探针6-[2-(2-叠氮基-5-[125I]碘苯甲酰基)乙基]-1-[(6-氯-3-吡啶基)甲基]-1,2,3,5,6,7-六氢-8-硝基咪唑并[1,2-c]嘧啶。该化合物（未标记）对果蝇头部膜中[3H]-IMI结合的IC50为8 nM，且125I标记的光亲和探针仅在被(-)-尼古丁抑制的特定位点标记一种66 kDa的蛋白质，这与nAChR的杀虫剂结合亚基一致。
