Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria. Australia.
Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria. Australia.
Biol Reprod. 2020 Aug 4;103(2):323-332. doi: 10.1093/biolre/ioaa117.
Sympathetically mediated contractions of smooth muscle cells in the vasa deferentia are mediated by neuronally released adenosine 5'-triphosphate (ATP) and noradrenaline, which stimulate P2X1-purinoceptors and α1A-adrenoceptors, respectively. This process is crucial for sperm transport, as demonstrated in knockout mouse studies where simultaneous genetic deletion of P2X1-purinoceptors and α1A-adrenoceptors resulted in male infertility. We hypothesize that dual pharmacological antagonism of these two receptors could inhibit sperm transport sufficiently to provide a novel nonhormonal method of male contraception. To generate a suitable P2X1-purinoceptor antagonist, substituents were introduced on the phenyl moiety of 2-phenyl-5,6,7,8-tetrahydroquinoxaline to create a series of analogues that were tested for P2X1-purinoceptor antagonism in isolated preparations of rat vas deferens. Novel compounds were initially screened for their ability to attenuate contractile responses to electrical field stimulation (EFS: 60 V, 0.5 ms, 0.2 Hz). The addition of polar substituents to the meta, but not ortho, position markedly increased the inhibition of contractions, as did the addition of both polar and aliphatic substituents to the para position. Di-substituted compounds were also synthesized and tested, resulting in a compound 31 (2-hydroxy, 4-fluoro), which exhibited the greatest potency, with an IC50 of 14 μM (95% confidence limits: 12-16 μM). Additionally, compound 31 noncompetitively antagonized contractions mediated by exogenously administered αß-methylene ATP (10 nM-30 μM) but had no inhibitory effect on contractions mediated by exogenously administered noradrenaline (30 nM-100 μM) or acetylcholine (30 nM-100 μM). These results have contributed to a structure-activity relationship profile for the P2X1-purinoceptor that will inform future designs of more potent antagonists.
输精管平滑肌细胞的交感神经介导收缩是由神经元释放的腺苷 5'-三磷酸 (ATP) 和去甲肾上腺素介导的，它们分别刺激 P2X1-嘌呤能受体和 α1A-肾上腺素能受体。这个过程对精子运输至关重要，正如在 knockout 小鼠研究中所证明的那样，同时遗传删除 P2X1-嘌呤能受体和 α1A-肾上腺素能受体导致雄性不育。我们假设这两种受体的双重药理学拮抗作用可以抑制精子运输，足以提供一种新的非激素男性避孕方法。为了生成合适的 P2X1-嘌呤能受体拮抗剂，在 2-苯基-5,6,7,8-四氢喹喔啉的苯基部分引入取代基，以创建一系列类似物，在大鼠输精管的分离制剂中测试它们对 P2X1-嘌呤能受体的拮抗作用。新化合物最初被筛选其减弱对电场刺激（EFS：60 V，0.5 ms，0.2 Hz）收缩反应的能力。在间位而非邻位引入极性取代基可显著增加收缩的抑制作用，在对位引入极性和脂肪取代基也是如此。还合成并测试了二取代化合物，得到化合物 31（2-羟基，4-氟），其抑制作用最强，IC50 为 14 μM（95%置信区间：12-16 μM）。此外，化合物 31 非竞争性拮抗外源性给予的 αß-亚甲基 ATP（10 nM-30 μM）介导的收缩，但对外源性给予的去甲肾上腺素（30 nM-100 μM）或乙酰胆碱（30 nM-100 μM）介导的收缩没有抑制作用。这些结果为 P2X1-嘌呤能受体的构效关系图谱做出了贡献，这将为更有效的拮抗剂的未来设计提供信息。
