Antioxidant effects of tetrahydro‐β‐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.

Formation, nutritional value, and enhancement of characteristic components in black garlic: A review for maximizing the goodness to humans

“…Using liquid chromatography–mass spectrometry (LC–MS), NMR, and hydrogen peroxide scavenging assay, Ichikawa et al. () identified alkaloids with significant antioxidant activity in an aged garlic extract: 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) diastereoisomers (as shown in Figure ). Sato, Kohno, and Niwano () reported that the contents of (1R, 3S)‐MTCC and (1S, 3S)‐MTCC in BG increased significantly after spontaneous fermentation at 60 to 70 °C and 85% to 95% relative humidity for 40 days, compared with those in FG (trace amounts).…”

“…The initial content of -carbolines in FG is mostly very low, but aging (for example, in aqueous ethanol, at room temperature, for 4 to 10 months) and thermal treatment (for example, 60 to 90 • C for 10 to 70 days) of FG can significantly increase the content of 1-methyl-1,2,3,4-tetrahydro--carboline derivatives (TH Cs), causing an increase in the hydrogen peroxide scavenging activity (Ichikawa et al, 2006). Using liquid chromatography-mass spectrometry (LC-MS), NMR, and hydrogen peroxide scavenging assay, Ichikawa et al (2002) identified alkaloids with significant antioxidant activity in an aged garlic extract: 1-methyl-1,2,3,4-tetrahydro-carboline-3-carboxylic acids (MTCC) and 1-methyl-1,2,3,4tetrahydro--carboline-1,3-dicarboxylic acid (MTCdiC) diastereoisomers (as shown in Figure 2). reported that the contents of (1R, 3S)-MTCC and (1S, 3S)-MTCC in BG increased significantly after spontaneous fermentation at 60 to 70 • C and 85% to 95% relative humidity for 40 days, compared with those in FG (trace amounts).…”

The Antioxidant Mechanisms Underlying the Aged Garlic Extract- and S-Allylcysteine-Induced Protection

“…Besides SAC, there are other compounds in AGE exhibiting antioxidant properties: (a) S-allylmercaptocysteine scavenges • OH and 1 O 2 [37]; (b) alliin scavenges • OH [38], O 2 •− [32], and H 2 O 2 [22] and inhibits lipid peroxidation [22]; (c) N α -(1-deoxy-D-fructos-1-yl)-L-arginine scavenges H 2 O 2 [8, 39] and also inhibits the Cu 2+ -induced low-density lipoprotein (LDL) oxidation and peroxides release during the coincubation of macrophages with oxidized LDL [39]; (d) tetrahydro-beta-carbolines show a strong H 2 O 2 scavenging activity while inhibit 2,2′-azobis(2-amidinopropane) hydrochloride-induced lipid peroxidation and nitrite production induced by lipopolysaccharide in murine macrophages [9, 10]. …”

Clinical and Experimental Study of the Toxic Neuropsychiatric Effects of Formaldehyde Exposure: Has Garlic a Protective Role?

“…The effectiveness of garlic has been related to its potent antioxidant properties [87] [88] [89]. Several studies were done on the health benefits of garlic, usually stated its sulfur containing metabolites as allicin and its derivatives.…”