Characterization of Antioxidant Activities in Red Dragon Fruit (Hylocereus polyrhizus) Pulp Water-based Extract

Abstract

The red dragon fruit, Hylocereus polyrhizus, locally known as Buah Naga has become increasingly popular among consumers and growers worldwide due to its antioxidative properties. The present study was conducted to examine the total phenolic content, total flavonoid content and antioxidant activities of water extract from fruit pulp of the species. The antioxidant activities were measured by DPPH (2,2-Diphenyl-1- picrylhydrazyl), ABTS (2-2’-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid), FRAP (Ferric Ion Antioxidant Power) and Phosphomolybdate assays. The total phenolic and flavonoid contents of pulp were recorded at 32.9 ± 0.92 mg GAE/100 mL and 2.26 ± 0.14 mg QE/100 mL of juice, respectively. The antioxidant or free radical scavenging activity, measured by the DPPH and ABTS protocols were 73.38 ± 2.24 % and 92.66 ± 0.22 %, respectively. The antioxidant capacity, determined by FRAP and Phosphomolybdate assays were 132.17 ± 3.74 µmol Fe2+/100 ml and 28.94 ± 0.83 mg AAE/100 mL of juice, respectively. The total phenolic and total flavonoid content in water extracts of pulp showed positively high correlations with DPPH, ABTS, FRAP and Phosphomolybdate assays. The results suggest that water, which is biodegradable and non-toxic, can be utilized to effectively extract active compounds in red dragon fruit pulp.