Evaluation of the Biological Activities of Different Parts of Dragon Fruit

Abstract

In this study, we examined the antioxidant (selenium, total polyphenol, and total flavonoid) contents and physiological activities (antioxidant, enzymatic, and anti-inflammatory effects) of the flesh and peel, which is typically discarded as waste, of Hylocereus undatus (dragon fruit). Selenium, total polyphenol, and flavonoid contents and DPPH and ABTS radical scavenging activities were higher in peel than flesh, and enzymatic activity assays also showed elastase and tyrosinase inhibitory activities were also higher in peel. In addition, flesh and peel extracts (0, 100, 1,000, or 2,000 μg/mL) did not significantly affect cell viability, and peel extract inhibited lipopolysaccharide-induced increases in NO, IL-1β, and IL-6 levels in RAW 264.7 macrophages significantly more than flesh extract. Correlation analysis on relations between antioxidant (selenium, total polyphenol, and total flavonoid) contents of peel extract and physiological activities (antioxidant, enzymatic, and anti-inflammatory) revealed positive relations with antioxidant and enzymatic activities but a negative correlation with inflammation. In conclusion, the peel of Hylocereus undatus was found to possess excellent antioxidant, enzymatic, and anti-inflammatory effects, which suggests its potential use as a new functional material.