DETERMINATION OF TOTAL PHENOLIC CONTENT (TPC) AND ANTIOXIDANT ACTIVITY OF LONGAN (Euphoria Longana) SEED AND PEEL EXTRACTS

Abstract

Longan (Euphoria longana) is a widely consumed fruit in Indonesia. The flesh is consumed, while the seed and the peel of Longan remain as waste despite of its chemical contents such as phenolic compounds (phenolic acids and flavonoids) with antioxidant properties. This study aimed to determine the total phenolic contents (TPC) and antioxidant activity of Longan seed and peel extract and to find out the relationship between total phenolic content and antioxidant activity. The seed and peel of Longan was separated from the flesh, then mashed and then dried. Furthermore, Longan seed was extracted by soxhletation method and fruit peel was extracted by maceration method using 96% ethanol as a solvent. The diluted extract was evaporated until a concentrated extract was obtained. The TPC was determined using Folin ciocalteu reagent and the absorption was measured using a UV-VIS spectrophotometer at a wavelength of 745 nm. Antioxidant activity was determined using 1,1-diphenyl-2-picryl-hydrazil (DPPH) reagent and the absorption was measured using a UV-VIS spectrophotometer at a wavelength of 516 nm. The TPC of Longan seed extract was 17.24% while fruit peel extract was 9.67%. Antioxidant activity expressed as IC₅₀ for seed extracts was 57.24 ppm(strong antioxidant) and fruit peel extracts was 120.82 ppm (moderate antioxidant). These results indicate that Longan seed extract has a higher TPC and stronger antioxidant activity compared to Longan fruit peel extract. It can be concluded that the higher the TPC the more active the antioxidant activity

Keywords : Longan Seed Extract, Longan Peel Extract, TPC, Antioxidant Activity