Proteins, polysaccharides and their derivatives as macromolecular antioxidant supplements: A review of in vitro screening methods and strategies

Owing to the implications of oxidative stress in disease and ageing process, antioxidant research has been a research hotspot. Antioxidants are derived from among the active components of plant and animal extracts, including macromolecular proteins, peptides and polysaccharides, and some small molecule peptides, phenols and flavonoids, among others. Exogenous antioxidant supplementation is effective in combating oxidative stress and promoting recovery from diseases and disease-associated processes, such as inflammation, atherosclerosis, and neurodegeneration. In clinical studies, antioxidant supplementation has been shown to mitigate disease exacerbation. Therefore, screening of antioxidants and the active substances in natural biological macromolecules is crucial. In vitro studies of antioxidant properties represent the first step in screening. Selection of a suitable method to evaluate the properties of antioxidant substances from biological macromolecules sources is particularly important. However, a critique of existing methods for comparing the antioxidant activities of macromolecular antioxidants is lacking. The aim of this review is to provide a set of redox reaction-based methods and application strategies to evaluate the antioxidant properties of natural biological macromolecules components. The paper describes the mechanisms, advantages, disadvantages and applicability of different in vitro methods for assessing antioxidant properties. In particular, a set of strategies for screening antioxidant supplements are discussed.