Free radical-mediated degradation of polysaccharides: Mechanism of free radical formation and degradation, influence factors and product properties

Increasing studies focus on the degradation of polysaccharides by free radicals. The review mainly provides an overview of degradation of polysaccharides by free radicals generated from hydrogen peroxide (H2O2). Evidence suggests that free radicals generated from H2O2 can be generated by various mechanisms. It broke glycosidic bonds mainly through hydrogen abstraction, causing the degradation of polysaccharides. Its degradation efficiency is affected by many factors, such as the concentration of polysaccharides and H2O2, temperature and pH. In addition, free radical degradation could change the physicochemical and structural properties of polysaccharides, such as water solubility, thermal stability, molecular weight, monosaccharide composition, apparent morphology, and chain conformation, but it had little effects on the primary structure of polysaccharides. Besides, free radical degradation could also improve the bioactivities of polysaccharides, including antioxidant, antitumor and anticoagulant activities.