Myocardial protection by propolis during prolonged hypothermic preservation

Oxidative stress is involved in the pathogenesis of ischemia-reperfusion during myocardial transplantation. Therefore, graft preservation solutions may be improved by supplementation with antioxidants to minimize graft dysfunction caused by cold ischemic injury. Propolis is a polyphenol-rich substance which has an important antioxidant activity. The protective effect of propolis against oxidative stress induced by prolonged cold preservation of heart was investigated. Mice were subjected to a hypothermic model of ischemia in which hearts were preserved for 24 h at 4 °C in Krebs-Hensleit (KH) solution in the absence or presence of propolis concentrations (50, 150 and 250 μg/ml). Levels of released Lactate dehydrogenase (LDH), Creatine phosphokinase (CPK) and Troponine-I (Trop I) were assessed in the preservation solution and histological assessement of heart ischemia injuries was performed. Oxidative stress biomarkers malondialdehyde (MDA) and advanced oxidation protein products (AOPP) and antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were assessed in cardiac tissue. Mitochondria were isolated from stored hearts and production of reactive oxygen species (ROS) was tested. Propolis supplementation protected efficiently hearts during preservation by reducing significantly levels of lipids and proteins oxidation and restoring activities of antioxidant enzymes. Also, propolis preserved tissue integrity altered by hypothermic ischemia in a concentration-dependent manner. Propolis reduced significantly the rate of H₂O₂ produced by mitochondrial respiration, the best antioxidant effect being obtained at the highest propolis concentration (250 μg/ml). Algerian propolis is a non-temperature sensitive scavenger that protects heart from oxidative damage induced by prolonged hypothermic ischemia.