Antioxidant effects of tetrahydro-β-carboline derivatives identified in aged garlic extract

Article type: Research Article

Authors: Ichikawa, Makoto | Ryu, Kenjiro | Yoshida, Jiro | Ide, Nagatoshi | Yoshida, Susumu | Sasaoka, Takashi | Sumi, Shin-Ichiro

Affiliations: Healthcare Research Institute, Wakunaga Pharmaceutical Co., Ltd., 1624, Shimokotachi, Koda-cho, Takata-gun, Hiroshima, 739-1195, Japan

Note: [] Address for correspondence: Nagatoshi Ide, Healthcare Research Institute, Wakunaga Pharmaceutical Co., Ltd., 1624, Shimokotachi, Koda-cho, Takata-gun, Hiroshima, 739-1195, Japan. Tel.: +81 826 45 2331; Fax: +81 826 45 4351; E-mail: [email protected]

Abstract: 1,2,3,4-Tetrahydro-β-carboline derivatives (THβCs) 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 THβCs; 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acids (MTCC) and 1-methyl-1,2,3,4-tetrahydro-β-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 μM. Our data suggest that these compounds are potent antioxidants in AGE, and thus may be useful for prevention of disorders associated with oxidative stress.

Keywords: aged garlic extract, tetrahydro-β-carboline derivatives, Maillard reaction products, antioxidant, LC-MS

Journal: BioFactors, vol. 16, no. 3-4, pp. 57-72, 2002