Evaluating the Potential of Phytochemicals as Natural Substitute for Synthetic Antioxidant: A Review

This study aimed at investigating the antioxidant potential of flavonoids as a subgroup of polyphenols and ultimately entirely and partially substitute the synthetic antioxidant with natural them. All relevant databases were searched for the terms including 'phytochemical', polyphenol', 'flavonoid', 'natural additive', as well as 'antioxidant activity' combined with in vivo and in vitro phrases. Free radicals are among the damaging factors to macromolecules. The oxidative reaction caused by these radicals is one of the reasons for food spoilage, which causes unpleasant odor, loss of taste, damaged tissue and appearance, and loss of nutritional value of exposed material. The common antioxidants employed in foods include Butylated hydroxytoluene (BHT), Butylated hydroxyanisole (BHA), Tert-butyl hydroquinone (TBHQ), and Propyl gallate (P.G.). Synthetic antioxidants have adverse effects such as causing mutation and carcinogenicity in the human body despite their high performance; hence, many studies have been carried out on replacing them with natural antioxidants. Phytochemicals and a widespread group of them known as polyphenols possess a high antioxidant activity. A major subset of polyphenols, Flavonoids, are secondary metabolites in plants with many applications. These compounds are potential antioxidants because of their capabilities, such as scavenging the free radicals donating hydrogen atoms, electrons, and chelate metal cations. The antioxidant mechanism of action of flavonoids is transferring hydrogen toward free radicals. Accordingly, the more the flavonoid structure makes the hydrogen transfer faster and easier, the more the flavonoid's antioxidant power will be. Therefore, the antioxidant activity of the flavonoids with hydroxy groups in their structure is higher among the different flavonoids. Besides health promotion and some disease prevention effects, various in vitro studies have shown that flavonoids possess a high antioxidant activity that is competitive with synthetic antioxidants. However, to make it commercially available, cheaper and high-performance extraction methods of flavonoids will have to be developed.