Antioxidant properties of small-molecule non-enzymatic compounds

Reactive oxygen species are molecules capable of independent existence, containing at least one oxygen atom and one or more unpaired electrons. Excessive formation of these molecules leads to oxidative stress. In recent years, there has been a growing interest in substances with antioxidant properties, reducing or preventing the harmful effects of free radicals. The compounds involved in antioxidant defence include endogenous and exogenous antioxidants, protecting body cells against the negative effects of oxygen radicals. The most important small-molecule non-enzymatic compounds found in food include ascorbic acid, retinol, β-carotene, tocopherol and polyphenolic compounds. Products of plant origin may provide a valuable source of bioactive compounds with antioxidant properties. It is believed that a diet rich in antioxidants may reduce the risk of developing several nutrition-related conditions as well as delay the ageing process. The aim of this review was to elucidate this topic and the state of the art about the role of plant orgin substances in counteraction of free radical reactions in human body.