Impact of extract conditions on total phenolic compounds and antioxidant activities of Phu Quoc sim fruits (rhodomyrtus tomentosa (ait.) hassk.)

Abstract

Rhodomyrtus tomentosa is an evergreen shrub that originates from Southeast Asia and grows in abundance with rose-pink flowers and dark-purple edible bell-shaped fruits. In this study, optimal extraction conditions for achieving high contents and antioxidant activities of the total phenolic compound (TPC) from Phu Quoc sim fruits were investigated. It was found that the total phenolic content achieved was upon 179.055mg gallic acid equivalent (GAE)/g dry weight extract (DWE) and the DPPH scavenging activity was 65.112% at concentration of 100µg/ml. The optimal extraction conditions were identified with 80% ethanol, with solid-to-solvent ratio of 1/4 (w/v), and 4 hours of extraction at the temperature of 60°C. Furthermore, the antioxidant activity of ethanol extract was found due to scavenging DPPH (IC₅₀=93.713µg/ml) and ABTS (IC₅₀=83.512µg/ml) radicals. Accordingly, Phu Quoc sim fruits was suggested a potential source of bioactive polyphenols with high antioxidant activities.