AKTIVITAS ANTIOKSIDAN EKSTRAK BUAH, DAUN, DAN RANTING BELIMBING MANIS (AVERRHOA CARAMBOLA L. ) DENGAN METODE DPPH DAN FRAP

• Main Author: Safitri, Irna
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39672
• Institution: Institut Teknologi Bandung

A free radical is a molecule that contains unpaired electron in its outer orbit which can be occurred from external factors such as exposure to cigarette smoke, UV light and pollutant, or pathological conditions. The balance between free radicals and antioxidants is needed for normal physiological functions. If free radicals more than the body's ability to regulate it, oxidative stress was occurred. Phenol and flavonoids are reducing agents and free radical scavengers that usually have antioxidant effects on plants. Star fruit (Averrhoa carambola L.) is a widely spread plant in Indonesia which used traditionally as food and contains a lot of flavonoids and vitamin C which act as an antioxidant. This study aims to examine the antioxidant activity of fruit, leaves, and branches of star fruit (Averrhoa carambola) with DPPH and FRAP methods by determining IC50 DPPH and EC50 FRAP; determine total phenol and total flavonoids and analyze their correlation to IC50 DPPH and EC50 FRAP; and analyze the correlation of IC50 DPPH and EC50 FRAP. Extraction was carried out using the reflux method using three solvents with different polarity, namely n-hexane, ethyl acetate, and ethanol. Determination of IC50 DPPH reduction, EC50 FRAP capacity, total flavonoids and total phenol from each extract was measured using UV-Visible spectrophotometry. Correlation between total flavonoid, phenolic content and IC50 DPPH, EC50 FRAP capacity was analyzed using Pearson method. Antioxidant activity of fruit, leaves and branches extracts of star fruit gave IC50 DPPH in the range of 3.14 - 83.36 µg/mL and EC50 FRAP were 30.19 - 1045.61 µg/mL. Ethyl acetate star fruit leaves extract had the highest total flavonoid content (37.19 g QE/100 g), while the highest total phenol content was given by ethanol star fruit leaves extract (10.14 g GAE/100 g). Total phenolic content in fruit, leaves and branches extracts had a negative and significant correlation with EC50 FRAP. All fruits, leaves, and branches extracts of star fruit were categorized as strong to very strong antioxidant, therefore potential to be developed as a source of natural antioxidants. Phenolic compounds were the main contributors in antioxidant activity of fruit, leaves and branches star fruit extracts using FRAP method. DPPH and FRAP methods did not give linear results in antioxidant activity of all samples.