ISOLASI METABOLIT SEKUNDER DARI JINTEN HITAM LOKAL (Nigella sativa L) DAN UJI AKTIVITAS ANTIOKSIDAN; ISOLATION OF SECONDARY METABOLITES OF LOCAL BLACK CUMIN (Nigella sativa L) AND DETERMINATION OF ANTIOXIDANT ACTIVITY

Andi Suhendi, Nurul Hidayat Aprilita

2014 | Disertasi | PROGRAM STUDI S2 ILMU KIMIA

This study was aimed to isolate secondary metabolites of the local black cumin seeds extract as quality indicator and determine antioxidant activity. Sample was obtained from local market, Pasar Gede, Solo which was origanally planted in Salatiga. This samples did not produce essential oils if it was distilled nwhile samples from Habasyah, Iran, India and Tunisia produced essential oils. Active compound from black cumin is thymoquinon which was identified using NMR and GCMS towards hexane and ethanol fractions. The antioxidant activities of fractions of hexane and ethanol extracts of black cumin were performed by DPPH (1, 1 – diphenyl-2-picryl hydrazyl) method. Compounds that have the potential as chemical markers were isolated in the hexane fraction by radial chromatography. Isolates were characterized by proton and carbon NMR and mass spectrometry. The antioxidant activity of ethanol extracts had IC50 value better than methanol extracts, but this result has not satisfied yet. To confirm the antioxidant activity, hexane and ethanol fractions of ethanol extract were asssessed. The results of hexane and ethanol fraction possesed IC50 value of 400.55 and 835.88 ppm, respectively. Thymoquinon did not identified by NMR and GCMS. Based on the spectra of 1H and 13C-NMR, the major components from hexane fraction were fatty acids derivatives, while in the ethanol fraction were sugar derivatives. Profiling results of hexane fraction extracts of black cumin with GCMS showed that the majority compounds were methyl ester octadeca-9,12-dienoic (32.03% with similarity index (SI) = 97%) and ethyl linoleic (19.84% with SI = 92%), while in the ethanol fraction were hexedecanoic acid methyl ester (31.33% with SI = 97%) and 9-octadecanoic acid methyl ester (25.58% with SI = 97%). Isolate obtained was strongly suspected linoleic acid based on data IR, 1H and 13C-NMR.

Kata Kunci : local black cumin, antioxidant, secondary metabolite, isolate.