Yu Yao and Amandio Vieira, Simon Fraser University, Canada
Abstract: Dietary antioxidants can complement the body’s endogenous antioxidant activities in moderating oxidative tissue damage. Citrus fruits are widely consumed and are considered an important source of dietary antioxidants, primarily vitamin C. Non-vitamin antioxidants such as flavonids may also contribute to total antioxidant activity of citrus fruits. From a public health perspective, there is growing evidence for decreased risk of major chronic diseases with increased consumption of flavonoid-rich foods such as citrus fruits and other plant-based foods. In this context, we have tested fruit juices from three Citrus species, C. aurantifolia, C. reticulata, and C. sinensis, in a previously standardized oxidation assay with potential pathological relevance. C. aurantifolia exhibited the most potent antioxidant activity, approximately 3-fold greater than the other two (P<0.05). The antioxidant activity of C. aurantifolia was greater than expected if such activity were based only on total phenolic content, or on reported vitamin C and E contents. Overall, this study characterizes the relative antioxidant potency of three Citrus species, identifies C. aurantifolia as the most potent, and suggests a major contribution of non-vitamin factors to total in vitro antioxidant potency of C. aurantifolia. Potential antioxidant factors are also suggested based on reported, relative phytochemical levels in the three species.
Keywords: antioxidant; Citrus aurantifolia; Citrus reticulata; Citrus sinensis; eriodityol; flavonoids; lime; nutrients; orange; polyphenols; vitamins