Isolasi dan Identifikasi Golongan Senyawa Flavonoida dari Biji Buah Namnam (Cynometra cauliflora L.)

Abstract

Cynometra cauliflora L. is a plant species in the Fabaceae family that had potential as a source of bioactive compounds, but phytochemical studies on its seeds were still limited. This study aims to isolate and identify flavonoid compounds from namnam fruit seeds. Isolation was carried out by macerating the seed powder with methanol solvent. The methanol extract was fractionated with ethyl acetate and liquid-liquid partitions with n-hexane solvent to obtain a concentrated methanol extract. The resulting extract was analyzed by TLC and further fractionated using column chromatography with a silica gel stationary phase and a chloroform:ethyl acetate mobile phase. The ratios that were used were 90:10; 80:20; 70:30; 60:40; 50:50; 40:60; 30:70; 20:80; and 90:10 (v/v). Purification of the pure compound was carried out through preparative TLC with a chloroform:ethyl acetate 60:40 (v/v) eluent. The isolate that was obtained was a yellow-brown amorphous solid weighing 4 mg (Rf = 0.3). The identification of the compound group was performed using UV-Vis spectrophotometry, FT-IR spectrophotometry, and 1H-NMR spectrophotometry techniques. Based on UV-Vis spectrophotometry analysis, two absorption peaks were found at wavelengths (λmax) of 330 nm and 274 nm. The FT-IR spectrum showed the presence of O-H, sp3 C-H, C=O ketone, aromatic C=C, asymmetric and symmetric C-O-C groups at wave numbers 3415.93; 2929.87; 1724.36; 1604.77; 1259.52; 1047.35 cm-1. In the 1H-NMR spectrum, a characteristic signal of the H-3 proton was identified at a chemical shift of δ6.54 ppm. Based on the integration of all data, it was concluded that the pure compound isolated is a flavone compound.