Melanoidins from dry fruit prevent oxidative endothelial cell death by counteracting mitochondrial oxidation and membrane depolarization

The cardiovascular benefits associated with diets rich in fruit and vegetables are thought to be due to phytochemicals contained in fresh plant material. Whether processed plant foods provide the same benefits as unprocessed ones is an open question. Melanoidins from heat-processed plums (prunes) and apricots were isolated and their presence confirmed by hydroxymethylfurfural content, colorimetric analysis and browning index. Oxidative injury of endothelial cells (ECs) is the key step for the onset and progression of cardiovascular diseases (CVD), therefore the potential protective effect of prune and apricot melanoidins on hydrogen peroxide-induced oxidative mitochondrial damage and cell death was explored in human ECs. The redox state of cytoplasmic and mitochondrial compartments was detected by using the redox-sensitive, fluorescent protein (roGFP), while mitochondrial membrane potential (MMP) was assessed with the fluorescent dye, JC-1. ECs exposure to hydrogen peroxide, dose-dependently induced mitochondrial and cytoplasmic oxidation. Additionally detected hydrogen peroxide-induced phenomena were MMP dissipation and ECs death. Pretreatment of ECs with prune and apricot melanoidins, significantly counteracted and ultimately abolished hydrogen peroxide-induced intracellular oxidation, mitochondrial depolarization and cell death, clearly indicating that melanoidins derived from heat processed prunes and apricots protect human ECs against oxidative stress.