title: Isolation, purification and identification of antioxidants in an aqueous aged garlic extract.
abstract: An aqueous aged garlic extract (AGE) was prepared by soaking sliced garlic in water for 20days at room temperature (23-25 °C). In order to locate the antioxidant ingredients of the aqueous AGE, an activity-guided fractionation approach using ABTS assay, DPPH assay and FRAP assay were conducted to guide the fractionation by means of extraction, column chromatography and semi-preparative HPLC. Some phenols and organosulfur compounds were identified as antioxidants in AGE by GC-MS. Furthermore, UV, IR, ESI-MS, NMR and specific rotation experiments led to the identification of l-phenylalanine, l-tryptophan, (3S)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, (1S,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, and (1R,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid as the major antioxidants in the AGE. The EC50 values of these purified tetrahydro-β-carboline derivatives were 0.625-1.334 μmol/mL and 1.063-2.072 μmol/mL in ABTS assay and DPPH assay, respectively. It is the first time for us to identify (3S)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid as an in vitro antioxidant in AGE.
authors.affiliation: Key Laboratory of Food Nutrition and Safety (Tianjin University of Science & Technology), Ministry of Education, Tianjin 300457, China.
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Food Nutrition and Safety (Tianjin University of Science & Technology), Ministry of Education, Tianjin 300457, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.affiliation: Key Laboratory of Food Nutrition and Safety (Tianjin University of Science & Technology), Ministry of Education, Tianjin 300457, China.
authors.forename: Yukun
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory of Food Nutrition and Safety (Tianjin University of Science & Technology), Ministry of Education, Tianjin 300457, China. Electronic address: zm0102@sina.com.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D052160:Benzothiazoles / Q000032:analysis; D002243:Carbolines / Q000032:analysis; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D005737:Garlic / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols / Q000032:analysis; D010649:Phenylalanine / Q000032:analysis; D010936:Plant Extracts / Q000032:analysis*; D013451:Sulfonic Acids / Q000032:analysis; D014364:Tryptophan / Q000032:analysis
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D002243:Carbolines; D010636:Phenols; D010936:Plant Extracts; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D010649:Phenylalanine; C038114:1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid; C054910:1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid; C009804:tryptoline; D014364:Tryptophan
keywords: Aged garlic extract; Antioxidants; Phenols; Tetrahydro-β-carboline derivatives