Procyanidines from Vitis vinifera seeds protect rabbit heart from ischemia reperfusion injury: Antioxidant intervention and/or iron and copper sequestering ability

An isolated rabbit heart Langendorff preparation paced electrically was used to evaluate the effects of a highly purified, high molecular weight fraction of oligomeric procyanidines isolated from Vitis vinifera seeds on myocardial reperfusion injury after 40 minutes of low flow (1 ml/min) ischemia. Infusion of the heart with 100 or 200 mu g/ml procyanidines dose-dependently reduced ventricular contracture during ischemia (LVEDP values decreased by 28% and 51%), decreased coronary perfusion pressure (CPP), improved cardiac mechanical performance upon reperfusion, increased the release of 6-keto-PGF(1 alpha) into the perfusate in both the pre-ischemic and the reperfusion periods (by 68% at 200 mu g/ml), and suppressed rhythm irregularity. This antiarrhythmogenic action was confirmed in a more severe model of ischemia (flow rate 0.2 ml/min). The cardioprotective agent allopurinol infused at 20 mu g/ml had effects on the contractility and on the release of 6-keto-PGF(1 alpha) comparable to those of 200 mu g/ml procyanidines. The results of the second part of this study show that procyanidines are potent scavengers of several reactive oxygen species involved in the ischemia/reperfusion damage: the superoxide anion (IC50 = 5.64 mu M; rate constant K = 7.55 x 10(5) M(-1) s(-1), determined by the phenazine methosulfate/NADH method); the hydroxyl radical (IC50 = 28 mu M; rate constant K = 1.2 x 10(12) M(-1) s(-1), determined by the electron spin resonance spectroscopy); peroxyl radicals (IC50 = 0.025 mu M and 0.35 mu M, determined using two different lipid substrates, phosphatidylcholine liposomes and methyl linoleate micelles by UV spectroscopy at 233 nm). Finally, procyanidines interact with Fe2+ and Cu2+ ions (the catalysts of HO. radicals production) giving rise to strong complexes, with stability constants (log K) ranging from 9.35 to approximate to 9.