Natural antioxidants

Antioxidants are compounds or systems that can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. They are important in prevention of plants pollution damage, disease prevention in both plants and animals and play an important role in the body defense system.

Antioxidants are categorized in two groups of synthetic and natural, which most of them are poly-substituted phenolic compounds. Natural antioxidants, easily obtained from natural sources, possess great potential to be used as preservatives, replacing the synthetic ones.

The use of plant extracts as natural antioxidants has received increased interest due to the concerns on negative health effects developed by the use of synthetic antioxidants. The factors that encourage the use of natural antioxidants are its low cost, compatibility with diet and less harmful effect in the human body.

A variety of plant materials are known to be natural sources of antioxidants, such as herbs, spices, seeds, fruits and vegetables. Also, due to toxicological concerns of synthetic antioxidants, phenolic compounds in plants were used to minimize or retard lipid oxidation in lipid-based food products. Fruits, vegetables and medicinal herbs are the richest sources of antioxidant compounds such as Vitamin A, C, E, β-carotene and important minerals.

Plant phenolics are multifunctional and can act as reducing agents, free radical terminators, metal chelators and singlet oxygen quenchers.

Some peptides with antioxidant activity occur naturally in food. Both glutathione (-Glu-Cys-Gly) and carnosine (β-alanyl-L-histidine) are antioxidants that are naturally present in muscle tissues. They have been found to scavenge hydroxyl radicals and quench singlet oxygen and inhibit lipid peroxidation.

Natural antioxidants from plants may be classified into three main classes: phenolic compounds, vitamins and carotenoids. Some phenolic compounds, in addition to being the major plant-compounds with antioxidant activity, also present antimicrobial and antifungal activities, and have important effects on the flavors and textures of food products.
Natural antioxidants