Procyanidines from Vitis vinifera Seeds Protect Rabbit Heart from Ischemia/Reperfusion Injury: Antioxidant Intervention and/or Iron and Copper Sequestering Ability

Abstract

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 µg/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_1α into the perfusate in both the pre-ischemic and the reperfusion periods (by 68% at 200 µg/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 µg/ml had effects on the contractility and on the release of 6-keto-PGF_1α comparable to those of 200 µg/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 µM; rate constant K = 7.55 × 10⁵M^-1 s^-1, determined by the phenazine methosulfate/NADH method); the hydroxyl radical (IC₅₀ = 28 µM; rate constant K = 1.2 × 10¹²M^-1 s^-1 determined by the electron spin resonance spectroscopy); peroxyl radicals (IC₅₀ = 0.025 µM and 0.35 µM, 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 ≈ 9.

Key words

Procyanidines - Vitis vinifera - Vitaceae - ischemia/reperfusion - antioxidant activity - metal chelators