The Anti-Aging Effects of Polyphenols: The Mitochondrial Perspective ^†

Aging is characterized by a progressive decline in organ and cellular functions, followed by greater susceptibility to various diseases and death. With the continuous rise in the elderly population, aging is identified as one of the major focus points of modern medicine, and targeting hallmarks of aging could represent one possible method of ameliorating aging [1,2,3]. To date, researchers have identified several hallmarks of aging, including mitochondrial dysfunction [4]. Specifically, during aging, there has been an observed increase in reactive oxygen species (ROS) production, reduced ATP synthesis, loss of mitochondrial membrane potential, excessive mutations of the mtDNA, changes in mitochondrial morphology, reduced mitochondrial number, and accumulation of damaged mitochondria [5,6,7,8]. Polyphenols are a group of natural compounds, found in various fruits and vegetables, that possess the ability to target multiple aging hallmarks [9,10]. All of the polyphenol subclasses—flavonoids, tannins, phenolic acids, coumarins, stilbenes, lignans, curcuminoids, and xanthonoids—can influence one or multiple mitochondrial pathways associated with aging: they can reduce ROS concentrations, improve ATP production and adenine nucleotide translocase (ANT) activity, influence electron transport chain function and mitochondrial fission and fusion, promote mitophagy and mitochondrial biogenesis, restore mitochondrial membrane potential, increase NAD⁺ levels, and promote sirtuin activity. The mentioned effects can be observed in vitro and in vivo, and can be accompanied by an improvement in age-related dysfunctions, such as exercise endurance, memory deficit, and visual function. Finally, polyphenols can extend lifespan by modulating mitochondrial functions, while the most prevalent exhibited effect is represented by ROS targeting.