The amino-3,5-dicyanopyridine derivatives belong to an intriguing series of adenosine receptor (AR) ligands that has been developed by both academic researchers and industry. Indeed, the studies carried out to date underline the versatility of the dicyanopyridine scaffold to obtain AR ligands with not only a wide range of affinities but also with diverse degrees of efficacies at the different ARs. These observations prompted us to investigate on the structure–activity relationships (SARs) of this series leading to important previously reported results. The present SAR study has helped to confirm the 1H-imidazol-2-yl group at R2 position as an important feature for producing potent AR agonists. Moreover, the nature of the R1 substituent highly affects not only affinity/activity at the hA1 and hA2B ARs but also selectivity versus the other subtypes. Potent hA1 and hA2B AR ligands were developed, and among them, the 2-amino-6-[(1H-imidazol-2-ylmethyl)sulfanyl]-4-[4-(prop-2-en-1-yloxy)phenyl]pyridine-3,5-dicarbonitrile (3) is active in the low nanomolar range at these subtypes and shows a good trend of selectivity versus both the hA2A and hA3 ARs. This combined hA1/hA2B partial agonist activity leads to a synergistic effect on glucose homeostasis and could potentially be beneficial in treating diabetes and related complications.
氨基-3,5-二氰吡啶衍生物属于一个引人注目的腺苷受体(AR)配体系列,这个系列是由学术研究人员和工业界共同开发的。事实上,迄今为止进行的研究强调了二氰吡啶骨架的多功能性,可以获得不仅具有广泛亲和力而且在不同AR上具有不同效力的AR配体。这些观察结果促使我们对这个系列的结构-活性关系(SARs)进行研究,从而得到了重要的先前报道的结果。当前的SAR研究有助于确认R2位置的1H-咪唑-2-基团是产生有效AR激动剂的重要特征。此外,R1取代基的性质不仅高度影响对hA1和hA2B AR的亲和力/活性,还影响对其他亚型的选择性。开发了有效的hA1和hA2B AR配体,其中2-氨基-6-[(1H-咪唑-2-基甲基)硫基]-4-[4-(丙-2-烯-1-氧基)苯基]吡啶-3,5-二腈(3)在这些亚型中的活性处于低纳摩尔范围,并显示出对hA2A和hA3 AR的良好选择性趋势。这种结合的hA1/hA2B部分激动剂活性对葡萄糖稳态产生协同效应,可能有助于治疗糖尿病及相关并发症。