Saprirearine protects H9c2 cardiomyocytes against hypoxia/ reoxygenation-induced apoptosis by activating Nrf2

Myocardial infarction is a major cause of mortality and disability worldwide. Ischemia/reperfusion injury is the key factor that results in the increase in infarct size in pathogenesis. To find a novel therapy for myocardial infarction, we have evaluated saprirearine, a natural diterpenoid, using H9c2 cardiomyocytes injured by hypoxia/ reoxygenation and explored the possible mechanisms. The results showed that saprirearine improved cell survival by increasing cell viability and blocking the release of lactate dehydrogenase. Meanwhile, saprirearine was found to attenuate mitochondrial dysfunction by inhibiting calcium overload, collapse of the mitochondrial membrane potential, and opening of the mitochondrial permeability transition pore. And oxidative stress resulting from hypoxia/reoxygenation was ameliorated by saprirearine through the reduction of reactive oxygen species and malondialdehyde as well as activation of superoxide dismutase and catalase. Additionally, saprirearine inactivated cysteinyl aspartate-specific proteinase-3, the up-regulated B-cell lymphoma-2 and down-regulated Bcl-2-associated X protein, to inhibit hypoxia/reoxygenation-induced apoptosis. Further research revealed saprirearine-activated nuclear factor E2-related factor-2 in H9c2 cardiomyocytes, which is closely associated with its protective effects. These findings can provide evidence for the discovery of new therapies targeting myocardial infarction and the application of saprirearine in clinical practice.