Author/Authors :
Songsungkan, J. Khon Kaen University - Faculty of Science, Center of Excellence for Innovation in Chemistry - Department of Chemistry, Thailand , Chanthai, S. Khon Kaen University - Faculty of Science, Center of Excellence for Innovation in Chemistry - Department of Chemistry, Thailand
Abstract :
This study presented the methanol/ethanol extraction of organosulfurs from a commercially available garlic capsule, commonly used as a herbal drug supplement, comparing with fresh and its baked garlic clove followed by its antioxidant activity evaluation by both 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 1,10-phenanthroline (Phen) methods. Using various ratios of methanol or ethanol in deionized water under stirring at ambient temperature, the highest antioxidant activities of the crude extract obtained from garlic (powder) capsule, fresh garlic clove and baked garlic powder were 224, 189 and 253 μg BHT/g DW for DPPH assay, and 9.5, 9.2 and 9.6 μg Fe/g DW for Phen assay, respectively. However, the garlic crude extract contained rather high contents of total phenolics, as determined by Folin-Ciocalteu reagent, of 554, 1866 and 536 μg GAE/g DW, respectively. When removal of total phenolics at least 10 folds using C18-SPE expecting only for an allicin, its antioxidant activity of the garlic capsule drastically decreased (88%) as the total phenolics decreased about 91%. Concerning the powder of the baked garlic clove, its antioxidant activity also decreased (82%) with removal of the phenolics (93%). While that of fresh garlic remained increase of 14% as its total phenolics decreased 92%. Therefore, the obtained antioxidant activity of which the organosulfurs in the garlic extract would be synergic results from the residual phenolics.
