Antioxidant activities of Rambutan (Nephelium lappaceum L) peel in vitro

Rambutan, Nephelium lappaceum L, peel due to consumption of fresh rambutan fruit is taken into account as waste, therefore the exploration of rambutan peel as a natural antioxidant is highly needed. The aim of this study is to investigate the antioxidant activity of rambutan peel from two cultivars (Aceh and Binjai) using ABTS radical assay of and ferric reducing activity power (FRAP) and to correlate with total phenolics and flavonoids. The powdered rambutan peel is extracted using maceration technique using methanol as extracting solvent. The methanolic extract is added with warm water and fractionated using petroleum ether, chloroform, and ethyl acetate to get corresponding fractions. Rambutan cultivar Binjai revealed the higher ABTS antiradical activity than that of cultivar Aceh. Furthermore, among methanolic extract and its fraction, ethyl acetate fraction exhibited the highest antiradical activity using ABTS radical with IC50 values of 3.10 μg/mL and 0.77 μg/mL for Aceh and Binjai, respectively. The ethyl acetate fraction also revealed the highest FRAP values of 1424.897 ± 28.56 μg/mg fraction sample (Aceh) and 968.57± 7.48 μg/mg fraction sample (Binjai). These activities were correlated with phenolics and flavonoid contents. Rambutan peel exhibited strong antioxidant activities, contained high amounts of phenolics and flavonoid and is potential to be developed as a functional food