title: Antioxidant effects of tetrahydro-beta-carboline derivatives identified in aged garlic extract.
abstract: 1,2,3,4-Tetrahydro-beta-carboline derivatives (THbetaCs) are formed through Pictet-Spengler chemical condensation between tryptophan and aldehydes during food production, storage and processing. In the present study, in order to identify the antioxidants in aged garlic extract (AGE), we fractionated it and identified four THbetaCs; 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids (MTCC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-1,3-dicarboxylic acid (MTCdiC) in both diastereoisomers using liquid chromatography mass spectrometry (LC-MS). Interestingly, these compounds were not detected in raw garlic, but the contents increased during the natural aging process of garlic. In in vitro assay systems, all of these compounds have shown strong hydrogen peroxide scavenging activities. (1S, 3S)-MTCdiC was found to be stronger than the common antioxidant, ascorbic acid. MTCC and MTCdiC inhibited AAPH-induced lipid peroxidation. Both MTCdiCs also inhibited LPS-induced nitrite production from murine macrophages at 10-100 microM. Our data suggest that these compounds are potent antioxidants in AGE, and thus may be useful for prevention of disorders associated with oxidative stress.
authors.affiliation: Healthcare Research Institute, Wakunaga Pharmaceutical Co., Ltd., 1624, Shimokotachi, Koda-cho, Takata-gun, Hiroshima, 739-1195, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ichikawa
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Ryu
authors.forename: Jiro
authors.initials: J
authors.lastname: Yoshida
authors.forename: Nagatoshi
authors.initials: N
authors.lastname: Ide
authors.forename: Susumu
authors.initials: S
authors.lastname: Yoshida
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasaoka
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Sumi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002243:Carbolines / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology*; D002460:Cell Line; D016166:Free Radical Scavengers / Q000494:pharmacology; D005737:Garlic / Q000737:chemistry*; D006861:Hydrogen Peroxide; D015227:Lipid Peroxidation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D051379:Mice; D009573:Nitrites / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry*; D013237:Stereoisomerism; D013997:Time Factors
chemical_list: D000975:Antioxidants; D002243:Carbolines; D016166:Free Radical Scavengers; D009573:Nitrites; D010936:Plant Extracts; C009804:tryptoline; D006861:Hydrogen Peroxide