Abstract: Nephelium lappaceum is a tropical fruit whose peel possesses antioxidant
properties. Experiments on the isolation and identification of the active constituents were
conducted, and on their antioxidant activity using a lipid peroxidation inhibition assay. The
methanolic extract of N. lappaceum peels exhibited strong antioxidant properties.
Sephadex LH-20 chromatography was utilized in the isolation of each constituent and the
antioxidant properties of each was studied. The isolated compounds were identified as
ellagic acid (EA) (1), corilagin (2) and geraniin (3). These compounds accounted for
69.3% of methanolic extract, with geraniin (56.8%) as the major component, and exhibited
much greater antioxidant activities than BHT in both lipid peroxidation (77-186 fold) and
DPPH•
(42-87 fold) assays. The results suggest that the isolated ellagitannins, as the
principal components of rambutan peels, could be further utilized as both a medicine and
in the food industry.