Discovery of 5-(3,4-dihydroxybenzylidene)-1,3-dimethylpyrimidine- 2,4,6(1H,3H,5H)-trione as a novel and effective cardioprotective agent via dual anti-inflammatory and anti-oxidative activities.

Myocardial ischemia/reperfusion (MI/R) injury is still the huge unmet medical need without effective therapy in clinic. It is critical to develop pharmacological intervention to scavenge ROS and inhibit NLRP3 activation to have a double benefit against MI/R injury. Cinnamamide derivatives have been demonstrated to possess anti-oxidative and anti-inflammatory activities. Previously, we have reported that a cinnamamide derivative 2 exerts excellent cardioprotective effect via mediation of intracellular oxidative stress via Nrf2 up-regulation against MI/R. In the present study, seventeen compounds have been optimized using cinnamamide-barbiturate hybrid 2 as the lead compound and their cardioprotective activities against MI/R were further determined in vitro and in vivo. Among them, compound 7 showed the most potent cardioprotective effect and low cytotoxicity. While cardiomyocytes were invased by hydrogen peroxide, compound 7 exhibited more excellent cardioprotective effect than that of luteolin and metoprolol, the positive control employed in the present study, as demonstrated by dramatically elevated cell survival rate and decreased LDH leakage rate. Moreover, compound 7 markedly inhibited cardiac expressions of inflammasome activation and pro-inflammatory cytokines release (i.e. NLRP3, IL-1β, IL-18), simultaneouly increasing endogenous antioxidative proteins (i.e. Nrf2, HO-1 and SOD) in vitro. In the rat MI/R model, compound 7 pretreatment profoundly reduced cardiac infarct size in MI/R rats and reversed abnormal changes in myocardial enzymes and lipid peroxidation levels in heart tissues. Mechanistically, compound 7 revealed significant cardioprotective effects by inhibiting NLRP3 and its downstream inflammatory chemokine IL-1β, as well as up-regulating Nrf2 in vivo. Furthermore, at the active site of the co-crystal of NLRP3 and Nrf2, compound 7 exhibited higher binding force in the molecular docking study, which was consistent with the in vitro results. Therefore, compound 7 is expected to be a potential cardioprotective agent possessing dual anti-inflammatory and anti-oxidative activities. Our work provides an important therapeutic strategy for the treatment of ischemic-reperfused heart disease.