Antioxidant Activity of Ethanolic Extract of Peel and Seed Melinjo (Gnetum gnemon) Based on Color Variations

Abstract

Melinjo (Gnetum gnemon Linn) is a plant of the genus Gnetacea that has been identified as having various biological activities, including antioxidants. This study aimed to analyze the biological activity of Gnetum gnemon for the determination of total phenolics, anti-free radicals (antioxidants), and the identification of chemical compounds contained in ethanol extract from the peel and inner seeds (endosperm). The total phenol and antioxidant activity of the peel and endosperm of G. gnemon seeds based on color variations have been investigated. The total phenolic content was analyzed by the Folin-Ciocalteu method. Antiox-idant activity was analyzed by NO, FRAP, and Trolox as comparison standards which showed antioxidant activity. Identification of compounds in the extract using Thin Layer Chromatography (TLC) and Gas Chromatography-Mass Spec-troscopy (GCSM). The results showed that the endosperm extract of the yellow seed G. gnemon had the highest total phenolic content, at 99.96 mg GAE/g sample and the lowest was in the red peel extract at 27.53 mg GAE/g sample. Likewise, the green seed extract had the highest NO scavenging activity of 43.80% and the lowest was the red peel extract which detected no inhibition of antioxidant activity. On the other hand, in the FRAP test, the activity of G. gnemon peel extract had a stronger reducing power than the endosperm seed extract in all color variations. The compound profile in the test extract showed a fairly clear spot of the compound under UV light at 366 nm and the stain appearance. About 10 compounds were detected in the GC-MS spectrum, which had a similarity index equal to or greater than 90%. However, there was no relationship between the maturity level of the melinjo color and the antioxidant activity tested.