Abstract

Rambutan (Nephelium lappaceum) is a tropical fruit belongs to the family (Sapindaceae) and it is native to Southeast Asia. Peel and seed are the by-product usually thrown away which may serve as a source of natural antioxidant. The objectives of this research were to determine the total phenolic content (TPC), total flavonoid content (TFC) and DPPH radical scavenging activity from aqueous and ethanolic extracts of rambutan seed and peel. Total phenolic content and total flavonoids content were evaluated using Folin-Ciocalteu reagent and aluminium chloride method, respectively. The antioxidant activity was tested using 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging assay. Aqueous extract of peel showed significantly (p<0.05) higher extraction yield of 29.97 ± 2.69%. The results showed ethanolic extract of peel exhibited the highest TPC of 244.00 ± 4.34 mg GAE/g. However, ethanolic extract of rambutan seed recorded highest total flavonoid content of 163.33 ± 1.88 QE/g. Rambutan peel demonstrated the highest free radical scavenging activity with inhibitory concentration (IC50) value of 24.99 ± 2.82 and 144.59 ± 1.36 μg/mL for ethanolic and aqueous extract, respectively. Positive correlations between total phenolic content and DPPH scavenging activity of peel and seed extracts were observed (r = 0.77, p<0.01). The present study suggests that rambutan peel can be utilized for the development of functional food.

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