Sugar, vitamin C, and polyphenols in commercial apple beverages and their effects on antioxidant and anti-inflammatory activities in vitro
The concentrations of sugar, vitamin C, and polyphenols, as well as antioxidant and anti-inflammatory capacity of commercial apple beverage products in Singapore, were not known. The concentrations of vitamin C, total polyphenol content, and specific polyphenols, quercetin, and catechin of commercial apple beverages were determined using their respective high-performance liquid chromatography – ultraviolet detection methods. 1,1-diphenyl-2-picrylhydrazyl assay and in vitro studies were conducted to examine the antioxidant and anti-inflammatory capacity. The apple beverages (n=17) exhibited significant antioxidant (DPPH radical scavenging assay, inhibition of cellular F2-isoprostanes and lipid hydroperoxide formation) and anti-inflammatory (inhibition of cellular leukotriene B4 formation and myeloperoxidase activity) capacity, which were found to be associated with vitamin C (10.35±1.18g/ 100g), total polyphenols (9.9±1.2mg GAE/ 100g), catechin (1.60±0.10mg/ 100g), and quercetin (0.46±0.09mg/ 100g) concentrations in the beverages. A separate simulation experiment demonstrated that antioxidant and anti-inflammatory capacity were augmented by increasing vitamin C, total and specific polyphenol concentrations.