Prodrugs (MRS7422, MRS7476) of highly selective A₃ adenosine receptor (AR) agonists Cl-IB-MECA and MRS5698, respectively, were synthesized by succinylation of the 2′ and 3′ hydroxyl groups, and the parent, active drug was shown to be readily liberated upon incubation with liver esterases. The prodrug MRS7476 had greatly increased aqueous solubility compared with parent MRS5698 and was fully efficacious and with a longer duration than MRS7422 in reversing mouse neuropathic pain (chronic constriction injury model, 3 μmol/kg, p.o.), a known A₃AR effect. MRS7476 (5 mg/kg, p.o., twice daily) was found to protect against non-alcoholic steatohepatitis (NASH) in the STAM mouse model, indicated by the NAFLD activity score. Hepatocyte ballooning, IL-10 production, and liver histology were significantly normalized in the MRS7476-treated mice, but not liver fibrosis (no change in ACTA2 levels) or inflammation. Hepatic expression of ADORA3 in human NAFLD patients was 1.9-fold lower compared to normal controls. Adora3 expression determined by qPCR in primary mouse liver was associated with the stellate cells, and its mouse full body A₃AR knockout worsened liver markers of inflammation and steatosis. Thus, we have introduced a reversible prodrug strategy that enables water solubility and in vivo activity of masked A₃AR agonists in models of two disease conditions.

高选择性 A ₃腺苷受体 (AR) 激动剂 Cl-IB-MECA 和 MRS5698 的前药（MRS7422、MRS7476）分别通过 2' 和 3' 羟基的琥珀酰化合成，母体活性药物显示出与肝酯酶孵育后很容易释放。与母体 MRS5698 相比，前药 MRS7476 的水溶性大大增加，并且在逆转小鼠神经性疼痛（慢性收缩损伤模型，3 μmol/kg，po）方面完全有效且持续时间比 MRS7422 更长，已知 A ₃AR效果。在 STAM 小鼠模型中发现 MRS7476（5 毫克/千克，口服，每日两次）可预防非酒精性脂肪性肝炎 (NASH)，由 NAFLD 活动评分表示。在 MRS7476 治疗的小鼠中，肝细胞气球样变、IL-10 产生和肝脏组织学显着正常化，但肝纤维化（ACTA2 水平没有变化）或炎症没有。与正常对照相比，人 NAFLD 患者中ADORA3 的肝脏表达低 1.9 倍。qPCR 测定的Adora3在原代小鼠肝脏中的表达与星状细胞相关，其小鼠全身 A ₃AR 敲除使炎症和脂肪变性的肝脏标志物恶化。因此，我们引入了一种可逆的前药策略，该策略使掩蔽的 A ₃ AR 激动剂在两种疾病状况的模型中具有水溶性和体内活性。