Epigallocatechin-3-gallate, a green tea catechin, protects the heart against regional ischemia–reperfusion injuries through activation of RISK survival pathways in rats

Abstract

Epigallocatechin-3-gallate (EGCG), the major catechin derived from green tea, has been shown to modulate numerous molecular targets in the setting of inflammation. This study aimed to determine whether EGCG protects against regional myocardial ischemia/reperfusion (I/R) injuries and its underlying mechanisms involving the role of reperfusion injury salvage kinase (RISK) pathways (PI3K-Akt and ERK 1/2) and GSK-3β or apoptotic kinases (p38 and JNK). The rats were subjected to I/R injuries consisting of 30 min ischemia followed by 2 h reperfusion. EGCG (10 mg/kg, intravenously) was administered alone or along with wortmannin (PI3K inhibitor, 0.6 mg/kg, intravenously) 5 min before the onset of reperfusion. Wortmannin was administered 10 min before the reperfusion. Infarct size was measured at the end of the reperfusion. The phosphorylation of Akt, GSK-3β, and MAPK kinases (ERK1/2, P38 and JNK) was determined by Western blotting after 10 min of reperfusion. EGCG reduced the infarct size compared with the control (25.4 ± 9.2 versus 43.2 ± 8.2 %, p < 0.05). Wortmannin alone did not affect the infarct size, but abolished the EGCG-induced infarct size limiting effect, indicating that EGCG may protect the heart by modulating the PI3K-Akt. EGCG significantly enhanced the phosphorylation of Akt and GSK-3β but not ERK1/2, while it reduced that of p38 and JNK. These results suggest that EGCG has a protective effect against regional myocardial I/R injuries through activation of the RISK pathway and attenuation of p38 and JNK. EGCG may have cardioprotective effects in patients undergoing surgeries prone to myocardial I/R injuries.