Preparation of proanthocyanidin–chitosan complex and its antioxidant and antibacterial properties

Abstract

Chitosan (CS) is a natural polysaccharide with beneficial effects on human health. To further strengthen its biological properties, a CS-based complex was prepared by combining it with proanthocyanidin (PA) and named it as PA–CS in this study. The successful preparation of PA–CS was confirmed by Fourier transform infrared spectroscopy. The size of PA–CS particles was distributed between 10 and 100 µm with a mean value of 30.6 µm and low pH and high salt concentration could increase their swelling ratio. The loading capacity of PA in PA–CS particles was 82.2 ± 1.7 mg/g, and an increased release of PA from the complex occurred at low pH and high salt concentration. After combination, PA–CS complex exhibited better antioxidant activity than CS, which is a result of the synergistic effects of PA and CS. The reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of PA–CS complex are mainly attributed to PA, whereas the superoxide radical scavenging activity of PA–CS complex largely depends on CS. Moreover, PA–CS complex showed similar diameters of inhibitory zone and identical minimal inhibitory concentrations compared with CS, suggesting that the antibacterial potential of PA–CS complex is similar to that of CS. In addition, after 20 days storage, PA–CS complex did not exhibit significant changes in DPPH radical scavenging activity and antibacterial activity, indicating the good stability of this complex.