2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid and tryptoline

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.

Topics: Antioxidants; Benzothiazoles; Carbolines; Chemical Fractionation; Chromatography, High Pressure Liquid; Garlic; Gas Chromatography-Mass Spectrometry; Magnetic Resonance Spectroscopy; Phenols; Phenylalanine; Plant Extracts; Sulfonic Acids; Tryptophan

Tetrahydro-beta-carbolines are biologically active alkaloids that occur and accumulate in mammalian tissues, fluids, and brain, but their ultimate origin or biological role is still uncertain. Four tetrahydro-beta-carboline alkaloids: 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, 1-methyl-1,2,3,4-tetrahydro-beta-carboline, and 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline, are found as naturally occurring substances in some fruit and fruit juices. These compounds occur in the microg/g level in those products, and a characteristic and distinct profile appears to exist depending on the type of fruit and juice involved. Thus, 1-methyl-1,2,3,4-tetrahydro-beta-carboline may appear in tomato, tomato juice, and kiwi; 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline in bananas, pineapple, tomato, and their corresponding juices; and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid in oranges and grapefruits, although it also occurred in most juices. Fruit-occurring tetrahydro-beta-carboline alkaloids acted as antioxidants and free radical scavengers in the ABTS assay when compared with ascorbic acid and Trolox. This suggests that tetrahydro-beta-carboline alkaloids might act as antioxidants when absorbed and accumulated in the body, contributing to the antioxidant effect of fruit products containing these compounds.

Topics: Actinidia; Alkaloids; Ananas; Antioxidants; Benzothiazoles; Beverages; Carbolines; Chromatography, High Pressure Liquid; Citrus; Free Radical Scavengers; Fruit; Mass Spectrometry; Musa; Solanum lycopersicum; Spectrometry, Fluorescence; Sulfonic Acids

Tetrahydro-beta-carboline alkaloids that occur in foods such as wine, seasonings, vinegar and fruit products juices, jams) acted as good radical scavengers (hydrogen- or electron donating) in the ABTS (2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) assay, and therefore, they could contribute to the beneficial antioxidant capacity attributed to foods. In contrast, the fully aromatic beta-carbolines norharman and harman did not show any radical scavenger activity in the same assay. During the reaction with ABTS.+ radical cation, tetrahydro-beta-carboline-3-carboxylic acid such as 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (MTCA) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-1,3-dicarboxylic acid (MTCA-COOH) were converted to harman, whereas 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (THCA) and 1,2,3,4-tetrahydro-beta-carboline-1,3-dicarboxylic acid (THCA-COOH) afforded norharman. These results suggest that food and naturally-occurring tetrahydro-beta-carboline alkaloids if accumulated in tissues, as reported elsewhere, might exhibit antioxidant activity.

Topics: Antioxidants; Benzothiazoles; Carbolines; Cations; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Food Analysis; Free Radicals; Gas Chromatography-Mass Spectrometry; Harmine; Indicators and Reagents; Models, Chemical; Sulfonic Acids; Time Factors