Sauchinone augments cardiomyocyte viability by enhancing autophagy proteins -PI3K, ERK(1/2), AMPK and Beclin-1 during early ischemia-reperfusion injury in vitro.

Background. Sauchinone has proved its anti-oxidant and anti-inflammatory properties in various animal tissues. This study sought to illustrate its regulatory nature on autophagy associated proteins (PI3K, ERK1/2, AMPK, and Beclin-1) during early cardiomyocyte ischemia and subsequent reperfusion. Methods. Cultured cardiomyocytes were subjected to simulated Ischemia/reperfusion with and without Sauchinone pretreatment and also in the presence of autophagy inhibitor (3-MA). Colorimetric analysis of CCK-8, LDH antibody assay as well as Western blot analysis were performed to observe the expressions of LC3B (II) and Beclin-1 protein (markers of autophagy), autophagy proteins (PI3K, ERK1/2 and AMPK) and apoptotic proteins (Bax and Bcl-2) and the results were quantified into their grey values and subjected to statistical analysis. Results. Sauchinone demonstrated cell survival enhancing properties with increase in CCK-8 (SD = 0.553±0.012) and decrease in LDH (SD = 0.183±0.054) expressions, both of which were best observed at test dose of 20 µmol/L. At this dose, there was increment in cellular autophagy as demonstrated by peaking of autophagy markers LC3B-II (p<0.05) and Beclin-1 (p<0.05) with strong correlations (r = 0.99). Similarly, the autophagy proteins, compared to control and I/R model, also showed a significant increased level with PI3K (p<0.0001), total p-ERK1/2 (p<0.0001) and p-AMPKα (p<0.0001). Simultaneously, a decrease in expressions of pro-apoptotic molecules Bax (r = 0.989, p<0.0001) with increment of in the anti-apoptotic protein Bcl-2 (r = 0.996, p<0.0001) was observed. The observed effects on cell density, viability and autophagy was abrogated in presence of 3-MA. Conclusions. Sauchinone enhances cell survival by promoting autophagy and inhibiting apoptosis in cardiomyocytes during early stages of Ischemia/reperfusion injury.