AKTIVITAS SINGLET OXYGEN QUENCHING SENYAWA FLAVONOID DARI EKSTRAK ETIL ASETAT TONGKOL JAGUNG (Zea mays)

Abstract

ABSTRAK

Penelitian ini bertujuan untuk mengisolasi dan mengkarakterisasi fraksi flavonoid dari ekstrak etil asetat tongkol jagung serta menentukan aktivitas singlet oxygen quenching. Tongkol jagung diekstraksi dengan cara refluk menggunakan etanol 80% selama 2 jam. Setelah itu disaring dan filtratnya diuapkan dengan rotary evaporator. Ekstrak etanol disuspensikan dalam air dan diekstraksi berturut turut dengan petroleum eter, etil asetat, butanol dan air. Fraksi pelarut terbaik difraksinasi dengan kromatografi kolom menggunakan silika gel 60 dan eluen n-heksana: etil asetat (4:6). Fraksi dievaluasi dalam singlet oxygen quenching dengan sistem reaksi fotooksidasi asam linoleat (0,03 M) dalam sistem emulsi yang mengandung 5,68 x 10^-3 mM eritrosin sebagai sensitiser dan campuran reaksi disinari cahaya fluoresen (4000 lux) selama 5 jam. Hasil karakteristik senyawa hasil isolasi (F2) berdasarkan hasil analisa UV-Vis terdapat 2 pita serapan pada panjang gelombang 289 nm (pita I) dan panjang gelombang 313 nm (II) yang mengindikasikan bahwa senyawa hasil isolasi termasuk golongan flavonoid jenis flavanon atau dihidroflavon. Spektra UV senyawa terisolasi dengan pereaksi geser kemungkinan memiliki gugus hidroksi yang terletak pada atom C-5 atau C-7. Analisis spektrofotometer infra merah (IR) menunjukkan adannya bilangan gelombang 3375 cm^-1 (OH, fenol), 2920 cm^-1 (CH), 1462 cm^-1 (C=C aromatik), 1604 cm^-1 (C=0) dan 1031 cm^-1 dan 1167 cm^-1 (C-O-C). Isolat (F2) memiliki aktivitas singlet oxygen quenching (antiphotooxidation) terhadap fotooksidasi asam linoleat yang mengandung eritrosin sebagai sensitizer.

ABSTRACT

The objective of this research was to isolate and characterized flavonoid fractions from corn cob ethyl acetate extract and to determine the singlet oxygen quenching activity. Corn cob was extracted with a reflux method using 80% ethanol solvent for two hours. After the extraction, filttering was occurred and the filtrate was evaporated with rotary evaporator. The ethanol extract was suspended in water and continually extracted with petroleum ether, ethyl acetate, buthanol and water. The best solvent fraction was fractionated with column chromatography using silica gel 60 and n-hexane and ethyl acetate (4:6) as eluent. The fraction was evaluated in singlet oxygen quenching with the photooxidation of linoleic acid (0.03 M) reaction system inside an emultion system that contains 5,68 x 10^-3 mM of eritrosin as sensitizer and the mixed reaction was lit by a fluorescent light (4000 lux) for 5 hours. The characteristic result of the isolated compound (F2) based on the UV-Vis analysis result there are two absorptopn band at 289 nm (band I) and 313 nm wavelength (band II) that indicate that the isolated compound belongs to the flavonoid group as a flavanon or a dihydroflavon type. The UV spectra of isolated compound with shifting reagent showed having a hydroxyl group located at the C-5 or C-7 atom. The infrared (IR) spectrophotometer analysis showed the wave number 3375 cm^-1 (OH, phenol), 2920 cm^-1 (CH), 1462 cm^-1 (C=C aromatic), 1604 cm^-1 (C=O) and 1031 cm^-1 and 1167 cm^-1 (C-O-C). The isolate (F2) has the singlet oxygen quenching activity (antiphotooxidation) on the photooxidation of linoleic acid that contain erythrosine as sensitizer.