| Pithecellobium jiringa, known as jengkol in Indonesia, is a tropical plant of the Leguminosae family in Southeast Asia regions. P. jiringa seed has been used in Indonesian typical culinary due to its high nutrition contents, meanwhile its peel is generally applied for natural food dye. In this study, we investigated antioxidant potentials of biomolecule and bioactive fractions from seed and peel parts of P. jiringa using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Biomolecule fractions (protein and polysaccharide) were extracted using precipitation techniques, while bioactive fractions, i.e. polyphenol and essential oil, were obtained from solvent extraction. All fractions were tested for their antioxidant potentials at various concentrations (10-250 µg mL-1). Ascorbic acid and Trolox were used as standard drugs. The optimal extraction yield was reached by polyphenol fractions from both P. jiringa seed and peel with values of 22.68% and 16.80%, respectively. Among all tested fractions, polyphenol fraction from P. jiringa peel at lowest concentration (10 µg mL-1) exerted the highest antioxidant activity (>80%) with the dose-independent profile. Its efficacy was slightly higher than Trolox. Meanwhile, protein and polysaccharide fractions from both seed and peel parts also had ~50% dose-independent antioxidant activity, similar to ascorbic acid. Thus, P. jiringa fractions from peel and seed parts may be potentially used for alternative natural antioxidant candidates with lowest dosage and high efficacy in vitro. |