Search

Abstract Background Patients with acute pancreatitis (AP) exhibit specific phenotypes of gut microbiota associated with severity. Gut microbiota and host interact primarily through metabolites; regrettably, little is known about their roles in AP biological networks. This study examines how enterobacterial metabolites modulate the innate immune system in AP aggravation. Methods In AP, alterations in gut microbiota were detected via microbiomics, and the Lactobacillus metabolites of tryptophan were identified by liquid chromatography-tandem mass spectrometry (LC–MS/MS). By culturing Lactobacillus with tryptophan, differential metabolites were detected by LC–MS/MS. Lipopolysaccharide (LPS)-stimulated RAW264.7 cells and mice with cerulein plus LPS-induced AP were used to evaluate the biological effect of norharman on M1 macrophages activation in AP development. Further, RNA sequencing and lipid metabolomics were used for screening the therapeutic targets and pathways of norharman. Confocal microscopy assay was used to detect the structure of lipid rafts. Molecular docking was applied to predict the interaction between norharman and HDACs. Luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to explore the direct mechanism of norharman promoting Rftn1 expression. In addition, myeloid-specific Rftn1 knockout mice were used to verify the role of Rftn1 and the reversed effect of norharman. Results AP induced the dysfunction of gut microbiota and their metabolites, resulting in the suppression of Lactobacillus-mediated tryptophan metabolism pathway. The Lactobacillus metabolites of tryptophan, norharman, inhibited the release of inflammatory factor in vitro and in vivo, as a result of its optimal inhibitory action on M1 macrophages. Moreover, norharman blocked multiple inflammatory responses in AP exacerbation due to its ability to maintain the integrity of lipid rafts and restore the dysfunction of lipid metabolism. The mechanism of norharman’s activity involved inhibiting the enzyme activity of histone deacetylase (HDACs) to increase histone H3 at lysine 9/14 (H3K9/14) acetylation, which increased the transcription level of Rftn1 (Raftlin 1) to inhibit M1 macrophages’ activation. Conclusions The enterobacterial metabolite norharman can decrease HDACs activity to increase H3K9/14 acetylation of Rftn1, which inhibits M1 macrophage activation and restores the balance of lipid metabolism to relieve multiple inflammatory responses. Therefore, norharman may be a promising prodrug to block AP aggravation. Graphical Abstract

芝麻油可能含有杂环胺9H-吡啶并\[3,4-b\]吲哚（norharman）和1-甲基-9H-吡啶并\[3,4-b\]吲哚（harman），为了有效检测芝麻油中杂环胺含量，建立了一种高效液相色谱-荧光检测法（HPLC-FLD），并对不同产地芝麻所制芝麻油中杂环胺含量进行对比。结果表明：所建立的HPLC-FLD能在15 min内实现对芝麻油中杂环胺的测定；在相同炒籽条件下，不同产地芝麻所制芝麻油中杂环胺含量有显著差异（p

Background: Patients with acute pancreatitis (AP) exhibit specific phenotypes of gut microbiota associated with severity. Gut microbiota and host interact primarily through metabolites; regrettably, little is known about their roles in AP biological networks. This study examines how enterobacterial metabolites modulate the innate immune system in AP aggravation. Methods: In AP, alterations in gut microbiota were detected via microbiomics, and the Lactobacillus metabolites of tryptophan were identified by liquid chromatography-tandem mass spectrometry (LC–MS/MS). By culturing Lactobacillus with tryptophan, differential metabolites were detected by LC–MS/MS. Lipopolysaccharide (LPS)-stimulated RAW264.7 cells and mice with cerulein plus LPS-induced AP were used to evaluate the biological effect of norharman on M1 macrophages activation in AP development. Further, RNA sequencing and lipid metabolomics were used for screening the therapeutic targets and pathways of norharman. Confocal microscopy assay was used to detect the structure of lipid rafts. Molecular docking was applied to predict the interaction between norharman and HDACs. Luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to explore the direct mechanism of norharman promoting Rftn1 expression. In addition, myeloid-specific Rftn1 knockout mice were used to verify the role of Rftn1 and the reversed effect of norharman. Results: AP induced the dysfunction of gut microbiota and their metabolites, resulting in the suppression of Lactobacillus-mediated tryptophan metabolism pathway. The Lactobacillus metabolites of tryptophan, norharman, inhibited the release of inflammatory factor in vitro and in vivo, as a result of its optimal inhibitory action on M1 macrophages. Moreover, norharman blocked multiple inflammatory responses in AP exacerbation due to its ability to maintain the integrity of lipid rafts and restore the dysfunction of lipid metabolism. The mechanism of norharman's activity involved inhibiting the enzyme activity of histone deacetylase (HDACs) to increase histone H3 at lysine 9/14 (H3K9/14) acetylation, which increased the transcription level of Rftn1 (Raftlin 1) to inhibit M1 macrophages' activation. Conclusions: The enterobacterial metabolite norharman can decrease HDACs activity to increase H3K9/14 acetylation of Rftn1, which inhibits M1 macrophage activation and restores the balance of lipid metabolism to relieve multiple inflammatory responses. Therefore, norharman may be a promising prodrug to block AP aggravation. [ABSTRACT FROM AUTHOR]

β-carbolines (harman and norharman) are potentially mutagenic and have been reported in some vegetable oils. Sesame seed oil is obtained from roasted sesame seeds. During sesame oil processing, roasting is the key procedure to aroma enhancement, in which β-carbolines are produced. Pressed sesame seed oils cover most market share, while leaching solvents are used to extract oils from the pressed sesame cake to improve the utilization of the raw materials. β-carbolines are nonpolar heterocyclic aromatic amines with good solubility in leaching solvents (n-hexane); therefore, the β-carbolines in sesame cake migrated to the leaching sesame seed oil. The refining procedures are indispensable for leaching sesame seed oil, in which some small molecules can be reduced. Thus, the critical aim is to evaluate the changes in β-carboline content during the refining of leaching sesame seed oil and the key process steps for the removal of β-carbolines. In this work, the levels of β-carbolines (harman and norharman) in sesame seed oil during chemical refining processes (degumming, deacidification, bleaching and deodorization) have been determined using solid phase extraction and high performance liquid chromatography-mass spectrometry (LC-MS). The results indicated that in the entire refining process, the levels of total β-carbolines greatly decreased, and the adsorption decolorization was the most effective process in reducing β-carbolines, which might be related to the adsorbent used in the decolorization process. In addition, the effects of adsorbent type, adsorbent dosage and blended adsorbent on β-carbolines in sesame seed oil during the decolorization process were investigated. It was concluded that oil refining can not only improve the quality of sesame seed oil, but also reduce most of the harmful β-carbolines. [ABSTRACT FROM AUTHOR]

Monoamine oxidase (MAO) oxidizes neurotransmitters and xenobiotic amines, including vasopressor and neurotoxic amines such as the MPTP neurotoxin. Its inhibitors are useful as antidepressants and neuroprotectants. This work shows that diluted soy sauce (1/3) and soy sauce extracts inhibited human MAO-A and -B isozymes in vitro, which were measured with a chromatographic assay to avoid interferences, and it suggests the presence of MAO inhibitors. Chromatographic and spectrometric studies showed the occurrence of the β-carboline alkaloids harman and norharman in soy sauce extracts inhibiting MAO-A. Harman was isolated from soy sauce, and it was a potent and competitive inhibitor of MAO-A (0.4 µM, 44 % inhibition). The concentrations of harman and norharman were determined in commercial soy sauces, reaching 243 and 52 μg/L, respectively. Subsequently, the alkaloids 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (THCA) and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) were identified and analyzed in soy sauces reaching concentrations of 69 and 448 mg/L, respectively. The results show that MTCA was a precursor of harman under oxidative and heating conditions, and soy sauces increased the amount of harman under those conditions. This work shows that soy sauce contains bioactive β-carbolines and constitutes a dietary source of MAO-A and -B inhibitors. [ABSTRACT FROM AUTHOR]

β-carbolines (harman and norharman) are potentially mutagenic and have been reported in some vegetable oils. Sesame seed oil is obtained from roasted sesame seeds. During sesame oil processing, roasting is the key procedure to aroma enhancement, in which β-carbolines are produced. Pressed sesame seed oils cover most market share, while leaching solvents are used to extract oils from the pressed sesame cake to improve the utilization of the raw materials. β-carbolines are nonpolar heterocyclic aromatic amines with good solubility in leaching solvents (n-hexane); therefore, the β-carbolines in sesame cake migrated to the leaching sesame seed oil. The refining procedures are indispensable for leaching sesame seed oil, in which some small molecules can be reduced. Thus, the critical aim is to evaluate the changes in β-carboline content during the refining of leaching sesame seed oil and the key process steps for the removal of β-carbolines. In this work, the levels of β-carbolines (harman and norharman) in sesame seed oil during chemical refining processes (degumming, deacidification, bleaching and deodorization) have been determined using solid phase extraction and high performance liquid chromatography-mass spectrometry (LC-MS). The results indicated that in the entire refining process, the levels of total β-carbolines greatly decreased, and the adsorption decolorization was the most effective process in reducing β-carbolines, which might be related to the adsorbent used in the decolorization process. In addition, the effects of adsorbent type, adsorbent dosage and blended adsorbent on β-carbolines in sesame seed oil during the decolorization process were investigated. It was concluded that oil refining can not only improve the quality of sesame seed oil, but also reduce most of the harmful β-carbolines.

Background: Norhraman is an alkaloid that can damage the nervous system. Objective: This experimental study aimed to investigate the effects of prenatal norharman exposure on seizure severity in adult rats. Methods: A total of 36 Wistar rats were randomly divided into 3 groups as follows: Control, sham (solvent), and norharman (1000 ug/kg). The sham and norharman groups were treated once daily for 8-18 of the fetal period. 2 months after birth, kindling was performed by the daily injection of Pentylenetetrazol (PTZ) (30 mg/kg); then, the seizure behavior was recorded for approximately 30 minutes. The obtained data were analyzed using Analysis of Variance (ANOVA) and Tukey’s posthoc test. Results: The present study data indicated that administrating norharman in the fetal period increased seizure responses to PTZ, i.e., significant in the examined female rats (P

Monoamine oxidase (MAO) oxidizes neurotransmitters and xenobiotic amines, including vasopressor and neurotoxic amines such as the MPTP neurotoxin. Its inhibitors are useful as antidepressants and neuroprotectants. This work shows that diluted soy sauce (1/3) and soy sauce extracts inhibited human MAO-A and -B isozymes in vitro, which were measured with a chromatographic assay to avoid interferences, and it suggests the presence of MAO inhibitors. Chromatographic and spectrometric studies showed the occurrence of the β-carboline alkaloids harman and norharman in soy sauce extracts inhibiting MAO-A. Harman was isolated from soy sauce, and it was a potent and competitive inhibitor of MAO-A (0.4 µM, 44 % inhibition). The concentrations of harman and norharman were determined in commercial soy sauces, reaching 243 and 52 μg/L, respectively. Subsequently, the alkaloids 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (THCA) and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) were identified and analyzed in soy sauces reaching concentrations of 69 and 448 mg/L, respectively. The results show that MTCA was a precursor of harman under oxidative and heating conditions, and soy sauces increased the amount of harman under those conditions. This work shows that soy sauce contains bioactive β-carbolines and constitutes a dietary source of MAO-A and -B inhibitors.

Background: Norhraman is an alkaloid that can damage the nervous system. Objective: This experimental study aimed to investigate the effects of prenatal norharman exposure on seizure severity in adult rats. Methods: A total of 36 Wistar rats were randomly divided into 3 groups as follows: Control, sham (solvent), and norharman (1000 ug/kg). The sham and norharman groups were treated once daily for 8-18 of the fetal period. 2 months after birth, kindling was performed by the daily injection of Pentylenetetrazol (PTZ) (30 mg/kg); then, the seizure behavior was recorded for approximately 30 minutes. The obtained data were analyzed using Analysis of Variance (ANOVA) and Tukey's posthoc test. Results: The present study data indicated that administrating norharman in the fetal period increased seizure responses to PTZ, i.e., significant in the examined female rats (P<0.05). Conclusion: According to the current research findings, the severity of seizures increases in subjects who have been exposed to norharman during the prenatal period. [ABSTRACT FROM AUTHOR]

Abstract Background Although the β-carboline alkaloids harman and norharman are considered as plant metabolites, they can also be secreted by fungi such as the entomopathogen Conidiobolus coronatus. Norharman and harman are also known to be reversible competitive monamine oxidase inhibitors, which increase serotonin concentrations in tissues. In addition, these alkaloids are able to bind to serotonin receptors, an important immune regulatory molecule in both vertebrates and invertebrates. In insects, serotonin modulates hemocyte phagocytosis, nodule formation and the populations of hemocyte classes. The present study examines whether harman and norharman may influence the phagocytic activity of insect hemocytes by regulating serotonin levels. Results Significantly greater serotonin levels and hemocyte phagocytic activity were observed after 24 h of exposure to food contaminated with harman and norharman. Similar responses were noticed 1 h after topical application or addition to in vitro hemocyte cultures. Observations and measurements performed 24 h later revealed decreased responses, suggesting decomposition and/or exertion of alkaloids and/or serotonin. Harman and norharman influenced the activity of Galleria mellonella plasmatocytes and the granulocyte cytoskeleton. Disturbances in hemocyte network formation, abnormal cell shape, naked nuclei, cell aggregates, fragments of disintegrated cells, interrupted cell membrane continuity and actin condensation in cells were observed. Conclusion Our findings may have a considerable impact on research concerning insect physiology, parasitology, immunology and biocontrol of pests. They confirm for the first time that harman and norharman (metabolites of the entomopathogenic fungus C. coronatus) elevate serotonin levels in G. mellonella hemocytes, thus potentially stimulating their phagocytic activity. Our studies shed light on the mechanisms underlying the interaction between innate insect immune responses and entomopathogen metabolites.

Copyright of Journal of Henan University of Technology Natural Science Edition is the property of Henan University of Technology Journal Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The β-carbolines in our diet, mainly including harman and norharman, are a group of biologically active, naturally occurring plant-derived alkaloids. Fragrant sesame seed oil is one of the most popular flavor edible oils in China. Considering that sesame seeds are roasted at 200–240 °C during the processing of flavor sesame seed oils, it is meaningful to investigate the levels of β-carboline compounds in various sesame seed oils. In this work, the levels of β-carbolines (harman and norharman) in different types of sesame seed oils in China (e.g., pressed fragrant sesame oil, ground fragrant sesame oil) have been determined systematically. The results showed that the levels of total β-carbolines in pressed fragrant sesame oils (700.5~2423.2 μg/kg) were higher than that in ground fragrant sesame oils (660.4~1171.7 μg/kg). Roasting sesame seeds at high temperatures (200–240 °C) led to higher levels of β-carbolines (660~2400 μg/kg) in fragrant sesame seed oils. In addition, the loss of tryptophan might be attributed to the formation of β-carbolines in sesame seeds during the roasting process. In general, fragrant sesame seed oils (pressed fragrant sesame oils, ground fragrant sesame oils) contain higher levels of β-carbolines due to the formation of harman and norharman during the roasting sesame seed process.

The β-carbolines, mainly including harman and norharman, are a group of naturally occurring, plant-derived alkaloids, and are also considered as nonpolar heterocyclic aromatic amines. Sesame seed oils contain a high level of β-carbolines (harman and norharman). In China, sesame seed oil blends are one of the most popular types of vegetable oils blends, which can be used as cooking oils or frying oils. Thus, it is meaningful to investigate the degradation of β-carbolines (harman and norharman) in sesame seed oil blends as frying oils during heating. In this work, the loss of harman and norharman in different types of sesame seed oil blends have been investigated. The results showed that the degradation of harman and norharman were dependent both on the type of oil blends, heating temperature and time. Harman and norharman were more degraded during heating (150 °C, 180 °C) in oleic acid-rich oil blends compared to polyunsaturated acid-rich oil blends. Mechanistic investigation suggested that the reduction in harman and norharman in oil blends during heating was mainly due to the oxidative degradation reaction between β-carbolines and lipid oxidation products. Therefore, the contents of β-carbolines (harman and norharman) in sesame seed oil blends when used as frying oils and heated can be decreased with prolonged cooking time.

The beta-carbolines norharman and harman, two heterocyclic aromatic amines with potential mutagenicity, have been determined in vegetable oils. Identification and analysis were carried out by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS). In 88 samples analysed, the concentrations of norharman and harman were < LOD to 336.22 ng/g and < LOD to 505.14 ng/g, respectively. A high variability of norharman and harman levels among different oil types was observed. Sesame-, flaxseed-, sunflower seed-, peanut- and rapeseed oils were most contaminated. Both β-carbolines were most likely formed during roasting of the oilseeds. Oil consumption, especially of oils obtained after roasting of the seeds, was a major dietary source of the β-carbolines norharman and harman. Under existing oil risk factors, this investigation contributes to the unprecedented and essential information for dietary assessments associated with oil consumption. [ABSTRACT FROM AUTHOR]

Heterocyclic amines (HCAs) are foodborne carcinogens for which their formation is highly dependent on cooking conditions. HCAs have been commonly quantified in food items prepared with simple procedures. This approach is suitable for elucidating HCAs' formation, but it only partially reflects the contamination in consumed food. In the current investigation, the generation of HCAs has been investigated in fried beef items prepared with elaborated cooking recipes, and their occurrence has been compared with control beef fried without the addition of ingredients other than oil. The food recipes that included a variety of food ingredients had lower yields of mutagenic HCAs (≥47% reduction, with individual HCA levels ranging between 0.01 and 2.22 ng/g) with respect to the control beef. In contrast, the co-mutagens norharman and harman were formed generally at greater levels (up to three times the contamination in the control fried beef) in the items prepared including a greater variety of ingredients. [ABSTRACT FROM AUTHOR]

The title compound, C21H14N2O2, was prepared by Pictet–Spengler cyclization of tryptamine and 4-formyl coumarin. In the molecule, the dihedral angle between the mean planes of the coumarin and β-carboline ring systems is 63.8 (2)°. In the crystal, molecules are linked via N—H...N hydrogen bonds, forming chains along the b-axis direction. Within the chains, there are a number of offset π–π interactions present [shortest intercentroid distance = 3.457 (2) Å].

Abstract: Aminomethylphenylnorharman (AMPNH) and aminophenylnorharman (APNH) are mutagenic norharman derivatives obtained from o‐toluidine and aniline, respectively. APNH is carcinogenic to the urinary bladder of rats and present in urine samples of healthy volunteers, indicating that norharman derivatives may be associated with cancer development in the urinary bladder of humans. To evaluate the possible role of AMPNH and APNH in bladder carcinogenesis, we examined the formation of γ‐H2AX, a DNA damage response marker, in the urinary bladder of rats. Seven‐week‐old male F344 rats were treated with 400 ppm AMPNH or 40 ppm APNH in the diet for 4 weeks. Animals were killed at the end of administration or after 2 weeks of recovery, and immunohistochemistry for γ‐H2AX and Ki67, a cell proliferation marker, was performed. At week 4, γ‐H2AX formation in bladder epithelial cells was significantly increased by APNH treatment as compared with that in controls. AMPNH also induced upregulation of γ‐H2AX formation, although there was no statistical significance. After the recovery period, γ‐H2AX‐positive cells were reduced but remained significantly higher in AMPNH and APNH groups than in the control group. Ki67‐positive cells were significantly increased by AMPNH and APNH at week 4 and reduced to the same level as the control after 2 weeks of recovery. Expression of KRT14, a bladder stem cell marker, was also increased in the basal layer by the two norharman derivatives. Thus, AMPNH and APNH showed in vivo genotoxicity in the bladder epithelium of rats, and APNH may be a potent causative agent of bladder carcinogenesis. [ABSTRACT FROM AUTHOR]

Rationale and objectives Nicotine and D-amphetamine can strengthen reinforcing effects of unconditioned visual stimuli. We investigated whether these reinforcement-enhancing effects reflect a slowing of stimulus habituation and depend on food restriction. Methods Adult male rats pressed an active lever to illuminate a cue light during daily 60-min sessions. Depending on the experiment, rats were challenged with fixed or varying doses of D-amphetamine (0.25–2 mg/kg IP) and nicotine (0.025– 0.2 mg/kg SC) or with the tobacco constituent norharman (0.03–10 μg/kg IV). Experiment 1 tested for possible reinforcement-enhancing effects of D-amphetamine and norharman. Experiment 2 investigated whether nicotine and amphetamine inhibited the spontaneous within-session decline in lever pressing. Experiment 3 assessed the effects of food restriction. Results Amphetamine (0.25–1 mg/kg) and nicotine (0.1 mg/kg) increased active lever pressing specifically (two- to threefold increase). The highest doses of nicotine and amphetamine also affected inactive lever responding (increase and decrease, respectively). With the visual reinforcer omitted, responding was largely extinguished. Neither drug appeared to slow habituation, as assessed by the within-session decline in lever pressing, and reinforcement-enhancing effects still occurred if the drugs were given after this decline had occurred. Food restriction enhanced the reinforcement-enhancing effect of amphetamine but not that of nicotine. Conclusions Responding remained goal-directed after several weeks of testing. Low doses of D-amphetamine and nicotine produced reinforcement enhancement even in free-feeding subjects, independent of the spontaneous within-session decline in responding. Reinforcement enhancement by amphetamine, but not nicotine, was enhanced by concurrent subchronic food restriction. [ABSTRACT FROM AUTHOR]

Monoamine oxidase inhibition is significant in smokers, but it is still unclear how the inhibition that is seen in the brains and bodies of smokers is brought about. Our aim was to test the contribution of the harman and norharman in tobacco smoke to MAO-A inhibition from tobacco smoke preparations, as part of a re-examination of harman and norharman as the cause of the inhibition of MAO-A inhibition in the brain. Tobacco smoke particulate matter and cigarette smoke particulate matter were prepared and the amounts of harman and norharman measured. The results were compared with the total monoamine oxidase-A inhibitory activity. At a nicotine concentration of 0.6 μM (a "physiological" concentration in blood) the total monoamine oxidase-A inhibitory activity measured in these samples was sufficient to inhibit the enzyme by approximately 10%. Of this inhibitory activity, only a small proportion of the total was found to be due to harman and norharman. These results show that harman and norharman provide only a moderate contribution to the total monoamine oxidase-A inhibitory activity of tobacco smoke, perhaps under 10%. This suggests that other inhibitors (either known or unknown) may be more significant contributors to total inhibitory activity than has yet been established, and deserve closer examination. [ABSTRACT FROM AUTHOR]

The title compound, C21H14N2O2, was prepared by Pictet-Spengler cyclization of tryptamine and 4-formyl coumarin. In the molecule, the dihedral angle between the mean planes of the coumarin and β-carboline ring systems is 63.8 (2)°. In the crystal, molecules are linked via N-H…N hydrogen bonds, forming chains along the β-axis direction. Within the chains, there are a number of offset π-π interactions present [shortest intercentroid distance = 3.457 (2) Å]. [ABSTRACT FROM AUTHOR]

[Display omitted] • 0.1 mmol of acrolein increased harman formation by 1375 %. • 0.1 mmol of acrolein increased norharman formation by 197 %. • 0.2 mmol of acrolein decreased the residue of tryptophan by 63.19 ± 3.81 %. • Acrolein might react with tryptophan, harman and norharman to eliminate them. • Six days of oxidation increased harman formation in roast beef patties by 315%. Harman and norharman were the most abundant β-carboline-type heterocyclic amines (HCAs) detected in various foodstuffs. Unsaturated fatty acids in foods may undergo rapid oxidative deterioration during transportation, storage and heat treatment, forming reactive carbonyl species (RCS). This work studied the effects of acrolein, a highly reactive RCS, on the formation of harman and norharman in the tryptophan model system. Results showed that 0.005, 0.01, 0.015, 0.02, 0.05, 0.1 and 0.2 mmol of acrolein led to harman production increased by 528 %, 752 %, 981 %, 1172 %, 1375 %, 1288 % and 768 % respectively, and led to norharman formation increased by 116 %, 129 %, 152 %, 169 %, and 197 %, 185 % and 157 %, respectively. Furthermore, acrolein addition reduced the residue of tryptophan (up to 63.19 %), but increased the level of the intermediates including formaldehyde (up to 352 %), acetaldehyde (up to 491 %), (1S,3S)-1-Methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA, up to 1936 %), and 1,2,3,4-tetrahydro-β-carboline-3-carboxylicacid (THCA, up to 2142 %) in the tryptophan model system. Acrolein might react with tryptophan, harman and norharman to eliminate them directly. These data suggested that acrolein may contribute to harman and norharman formation through participating in the above complex chemical reactions. In addition, the content of harman and norharman produced in roast beef patties made of minced beef oxidized for 2, 4, 6, 8, and 10 days increased by 118 %, 188 %, 267 %, 137 %, and 48 %, respectively, and led to norharman formation increased by 140 %, 132 %, 90 %, 86 %, and 74 %, respectively compared with those made of fresh minced beef, which further illustrated that lipid oxidation products potentially contributed to harman and norharman formation. [ABSTRACT FROM AUTHOR]

Monoamine oxidase (MAO) enzymes (MAO A and B) catalyze the oxidative deamination of biogenic amines, neurotransmitters, and xenobiotic amines and contribute to the regulation of the content of these active substances in mammalian organisms. The oxidation of biogenic amines by MAO produces hydrogen peroxide (H 2 O 2 ) and aldehydes that represent risk factors for oxidative injury. The inhibitors of MAO are useful as antidepressants and neuroprotective agents. Usually, the assays of MAO determine amine deamination products or measure the H 2 O 2 released by using direct spectrophotometric or fluorimetric methods. Direct methods are more prone to interferences and can afford inaccurate results. Those limitations can be avoided by using chromatographic techniques. This work describes a chromatographic method to assay MAO A and MAO B activity by using kynuramine as a nonselective substrate and the subsequent analysis of 4-hydroxyquinoline by RP-HPLC-DAD-fluorescence and mass spectrometry (MS). Alternatively, the assay uses the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin as a substrate of MAO that is oxidized (bioactivated) to neurotoxic pyridinium cations which are analyzed by HPLC. These methods are applied to assess the inhibition of MAO by bioactive β-carboline alkaloids occurring in foods, plants, and biological systems., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Heterocyclic aromatic amines (HAAs) are a class of hazardous compounds produced in food thermal processing. These compounds raise concerns because they have mutagenic and carcinogenic properties. However, the neurotoxicity of these compounds has received limited attention. Here, the toxic effects of three HAAs, i.e. 9H-pyrido[3,4- b ]indole (Norharman), 1-methyl-9H-pyrido[3,4- b ]indole (Harman), and 2-amino-3-methylimidazole[4,5- f ]quinoline (IQ) were investigated in Neuro-2a cells model. The results showed that the survival rate of cells decreased in a dose-dependent manner and apoptosis occurred after exposure to the three HAAs for 24 h and 48 h. Their neurotoxicity was ranked as Harman > Norharman > IQ. Further, treatment of Harman, Norharman, or IQ at 50 and 100 μM for 48 h led to intracellular REDOX imbalance, which was manifested as increased ROS and malondialdehyde (MDA) levels, decreased GSH/GSSG ratio, and reduced SOD and CAT activities. Moreover, Norharman and Harman up-regulated the expression level of nuclear factor erythroid 2-related factor 2 (Nrf2), as well as the mRNA levels of Heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoredutase1 (NQO1), while IQ had no significant effect on the levels of Nrf2, HO-1, and NQO1. Additionally, Harman, Norharman, or IQ exposure significantly reduced mitochondrial membrane potential and intracellular ATP levels and up-regulated the levels of apoptosis-related genes and proteins. Collectively, our finding suggested that HAAs were neurotoxic, with mechanisms related to induction of oxidative stress and mitochondrial dysfunction. [ABSTRACT FROM AUTHOR]

The β-carboline compounds norharman and harman exhibit neuroactive activity in the human body. Chicory coffee has proved to be a source of β-carboline compounds. This study assessed the norharman and harman contents of traditional and novel raw materials for the production of chicory coffee, as well as in samples of chicory coffee with novel additives. The highest content of the β-carbolines among the traditional raw materials was recorded in roasted sugar beet (2.26 μg/g), while roasting the chicory caused a 25-fold increase in the content of norharman in this raw material (from 0.05 to 1.25 μg/g). In novel raw materials not subjected to the action of high temperature, β-carboline was not detected. Among the roasted novel raw materials, the highest contents of harman and norharman were found in artichokes. High harman levels were also recorded in roasted chokeberry. [ABSTRACT FROM AUTHOR]

The β-carbolines in our diet, mainly including harman and norharman, are a group of biologically active, naturally occurring plant-derived alkaloids. Fragrant sesame seed oil is one of the most popular flavor edible oils in China. Considering that sesame seeds are roasted at 200–240 °C during the processing of flavor sesame seed oils, it is meaningful to investigate the levels of β-carboline compounds in various sesame seed oils. In this work, the levels of β-carbolines (harman and norharman) in different types of sesame seed oils in China (e.g., pressed fragrant sesame oil, ground fragrant sesame oil) have been determined systematically. The results showed that the levels of total β-carbolines in pressed fragrant sesame oils (700.5~2423.2 μg/kg) were higher than that in ground fragrant sesame oils (660.4~1171.7 μg/kg). Roasting sesame seeds at high temperatures (200–240 °C) led to higher levels of β-carbolines (660~2400 μg/kg) in fragrant sesame seed oils. In addition, the loss of tryptophan might be attributed to the formation of β-carbolines in sesame seeds during the roasting process. In general, fragrant sesame seed oils (pressed fragrant sesame oils, ground fragrant sesame oils) contain higher levels of β-carbolines due to the formation of harman and norharman during the roasting sesame seed process. [ABSTRACT FROM AUTHOR]

Highlights: [•] The second derivative synchronous fluorescence method has been developed. [•] Simultaneous determination of harman and norharman was carried out. [•] It is difficult to determine them simultaneously using conventional fluorimetry. [•] Overlapping spectra was resolved by second derivative synchronous fluorimetry. [•] Derivative synchronous spectrum, maintaining a constant difference of Δλ =150nm. [Copyright &y& Elsevier]

Abstract: β-Carbolines (BCs) are considered to be endogenous toxins and have been proposed as possible causative candidates inducing Parkinson''s disease (PD). However, there is controversy about the effect and also effective dose of these compounds in the etiology of PD. This study was designed to further examine the effect of norharman (NH), a BC which in mammalian brain occurs at high levels in the substantia nigra, on the development of Parkinsonism-like behaviors in rats. A small amount (4μl) of NH solution at 2 or 200ng/ml was unilaterally injected into either striatum or substantia nigra (SN) by stereotaxic surgery. The development of Parkinsonism was assessed by three conventional behavioral tests, compared to the effects of unilateral 6-hydroxydopamine (6-OHDA) — induced lesions in the nigrostriatal pathway. An apomorphine‐induced rotational test revealed no Parkinsonism‐like behavior in the NH treated groups. However, rats that received the high concentration of NH into their SN showed significant biased swings in the elevated body swing test. In a rotarod test, NH treated groups showed relatively weak motor performance and their learning patterns were close to that of the 6-OHDA treated rats. Considering that the rotational test is only valid in animals with severe Parkinsonism, but time spent on the rotating rod correlates inversely with severity of Parkinsonism, our results indicate that a single exposure to low amounts of NH is effective in producing moderate Parkinsonism-like behavioral symptoms, possibly through a neurotoxic effect of this agent on the SN dopaminergic neurons. [Copyright &y& Elsevier]

Inhibition of monoamine oxidase is one way to treat depression and anxiety. The information now available on the pharmacokinetics of flavonoids and of the components of tobacco prompted an exploration of whether a healthy diet (with or without smoking) provides active compounds in amounts sufficient to partially inhibit monoamine oxidase. A literature search was used to identify dietary monoamine oxidase inhibitors, the levels of these compounds in foods, the pharmacokinetics of the absorption and distribution, and tissue levels observed. An estimated daily intake and the expected tissue concentrations were compared with the measured efficacies of the compounds as inhibitors of monoamine oxidases. Norharman, harman and quercetin dietary presence, pharmacokinetics, and tissue levels were consistent with significant levels reaching neuronal monoamine oxidase from the diet or smoking; 1,2,3,4-tetrahydroisoquinoline, eugenol, 1-piperoylpiperidine, and coumarin were not. Quercetin was equipotent with norharman as a monoamine oxidase A inhibitor and its metabolite, isorhamnetin, also inhibits. Total quercetin was the highest of the compounds in the sample diet. Although bioavailability was variable depending on the source, a healthy diet contains amounts of quercetin that might give sufficient amounts in brain to induce, by monoamine oxidase A inhibition, a small decrease in neurotransmitter breakdown. [ABSTRACT FROM AUTHOR]

Abstract: β-Carbolines (BCs) are considered as endogenous neurotoxins that may contribute to the pathogenesis of Parkinson''s disease (PD). However, several lines of evidences show that these compounds have neuroprotective effect. This study was designed to assess effect of long term exposure to norharman, a BC compound which in mammalian brain occurs at high levels in the substantia nigra, on the progress of parkinsonism induced by 6-hydroxydopamine (6-OHDA). Animals were daily treated by norharman at doses 100, 200 and 1000μg/kg (i.p.) just before to four weeks after the intrastriatal injection of 6-OHDA. Statistical analysis of apomorphine-induced rotation tests demonstrates that treatment by norharman at doses 200 and 1000μg/kg for four weeks exacerbates significantly behavioral symptoms of the parkinsonism. To explore mechanisms by which norharman affects nigral dopaminergic cells, we studied the role of L-type Ca2+ channels. For this purpose, animals were daily treated with either L-type Ca2+ channel blocker of nifedipine at doses 2 and 5mg/kg (i.p.) or nifedipine together with norharman before to four weeks after the 6-OHDA injection. While treatment with nifedipine improved behavioral symptoms of the parkinsonism, treatment with both nifedipine and norharman had no affect on these symptoms. This data indicates that long term exposure to BCs promote nigral dopaminergic cell death possibly through L-type Ca2+ channels. [Copyright &y& Elsevier]

Abstract: Norharman and harman are two neuroactive β-carbolines present in several plants and thermally processed foods, including roasted coffee. The objective of this study was to evaluate their amounts in commercial instant coffee-based and coffee substitute beverages (n =48), with variable amounts of coffee, chicory, barley, malt, and rye. All samples contained variable amounts of both β-carbolines, always with a higher proportion of norharman than harman. The highest levels (p <0.01) were found in 100% instant coffees, with mean amounts of 3.8μg/g and 1.5μg/g for NH and H, respectively, followed by plain chicory. The lowest amounts were found in 100% barley, with 1.1μg/g for NH and 0.3μg/g for H. The NH and H content was statistically higher (p <0.01) in all mixtures with coffee when compared to those without it. Nevertheless, and except for 100% barley, the amounts provided by beverages based on coffee substitutes are within those reported for standard coffee brews. [Copyright &y& Elsevier]

β-carboline heterocyclic amines (β-CHAs) are substances widely present in food products, and are considered to have synergistic teratogenicity. In this study's experiments, the dry-heated glucose (Glc)-containing soy protein isolate (SPI) was used as a model to examine the effects of tetrahydro-curcumin (THC) on the formation of β-CHAs. The structural characteristics of the protein, ninhydrin-reactive amino nitrogen (NRAN), changes in antioxidant properties, and so on, before and after heat treatments were studied at the same time. The results showed that 1 g/100 g Glc in SPI could inhibit the formation of 1-methyl-9H-pyrido [3,4- b ]indole (Harman), while promoting the formation of 9H-pyrido [3,4- b ]indole (Norharman). THC could inhibit Norharman formation during the dry heat processes of Glc-containing SPI when the addition content was 1 g/100 g (P < 0.05), and the inhibitory effects increased with the increases in the content of THC. In addition, a 5 g/100 g content of THC was observed to significantly inhibit the formation of Harman. β-CHAs and protein structures displayed good correlations, which indicated that interactions between food components may be one of the ways for exogenous additives to inhibit the formation of β-CHAs in protein foods. • Glucose enhanced the formation of Norharman in dry-heated SPI. •The tetrahydrocurcumin had a dose-related inhibition on the formation of Norharman. •The formation of Harman in dry-heated SPI was simultaneously inhibited by glucose. •The 5 g/100 g tetrahydrocurcumin had an inhibition on the formation of Harman. [ABSTRACT FROM AUTHOR]

The β-carbolines, mainly including harman and norharman, are a group of naturally occurring, plant-derived alkaloids, and are also considered as nonpolar heterocyclic aromatic amines. Sesame seed oils contain a high level of β-carbolines (harman and norharman). In China, sesame seed oil blends are one of the most popular types of vegetable oils blends, which can be used as cooking oils or frying oils. Thus, it is meaningful to investigate the degradation of β-carbolines (harman and norharman) in sesame seed oil blends as frying oils during heating. In this work, the loss of harman and norharman in different types of sesame seed oil blends have been investigated. The results showed that the degradation of harman and norharman were dependent both on the type of oil blends, heating temperature and time. Harman and norharman were more degraded during heating (150 °C, 180 °C) in oleic acid-rich oil blends compared to polyunsaturated acid-rich oil blends. Mechanistic investigation suggested that the reduction in harman and norharman in oil blends during heating was mainly due to the oxidative degradation reaction between β-carbolines and lipid oxidation products. Therefore, the contents of β-carbolines (harman and norharman) in sesame seed oil blends when used as frying oils and heated can be decreased with prolonged cooking time. [ABSTRACT FROM AUTHOR]

Abstract: The effects of harman and norharman on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells were investigated. Harman and norharman at a concentration of 20 μM and 100 μM showed 49.4% and 49.5% inhibition of dopamine content for 48 h, respectively. The IC50 values of harman and norharman were 21.2 μM and 103.3 μM. Dopamine content, tyrosine hydroxylase (TH) activity and TH mRNA levels were decreased during the first 6 h, maintained for up to 48 h and then gradually recovered at 72 h after exposure to 20 μM harman and 100 μM norharman. Under the same conditions, the intracellular cyclic AMP levels and Ca2+ concentrations were also decreased by harman and norharman. In addition, harman and norharman at concentrations higher than 80 μM and 150 μM caused cytotoxicity at 48 h in PC12 cells. Non-cytotoxic ranges of 10–30 μM harman and 50–150 μM norharman inhibited L-DOPA (20–50 μM)-induced increases in dopamine content at 48 h. Harman at 20–150 μM and norharman at 100–300 μM also enhanced L-DOPA (20–100 μM)-induced cytotoxicity at 48 h with an apoptotic process. These results suggest that harman and norharman inhibit dopamine biosynthesis by reducing TH activity and enhance L-DOPA-induced cytotoxicity in PC12 cells. [Copyright &y& Elsevier]

The formation of heterocyclic amines (HCAs) was studied during frying of beefburgers with different fat contents (6.7%, 16.1% and 39%). Beefburgers were fried from the frozen state for 60, 90, 120 s, and until the centre temperature had reached 72 °C (approximately 150 s) in a double-sided pan fryer. The beefburgers were analysed for HCAs with solid-phase extraction and LC/MS detection, and 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5- f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP), 1-methyl-9H-pyrido[3,4- b]indole (Harman) and 9H-pyrido[3,4- b]indole (Norharman) were detected in all samples. The concentrations of HCAs ranged between 0 and 2.3 ng g−1. The HCAs concentrations were fitted to a first-order reaction model. The amounts of HCAs in beefburgers fried from the frozen state were in the same range as in beefburgers that have reached room temperature before frying. Furthermore, it was found that the formation of HCAs is not only concentration-controlled but also mass transport-controlled and that kinetic models stated in earlier studies fit relatively well our analysed values on HCAs in fried beefburgers. [ABSTRACT FROM AUTHOR]

The food contaminant norharman structurally resembles MPTP a compound that selectively damages pigmented brain areas. Both compounds are sequestered and retained in melanin-containing neurons. The aim of the study was to examine whether intracellular melanin can modulate the toxicity of norharman in melanin-loaded PC12 cells. Dopamine melanin protected against norharman-induced upregulation of grp78, activation of caspase 3 and necrosis at low concentrations (5 and 50 µM). In contrast, at a high conentration (500 µM) there was a significantly increased expression of grp78, hsp90 and caspase 3 and a disassociation of melanin aggregates leading to dispersal of granules to swollen neurite terminals. In human populations, a long-term low-level exposure to toxicants with a high affinity to melanin will probably result in accumulation in melanin-containing neurons in vivo. Our data suggest that accumulation of a neurotoxicant in melanin-loaded cells may lead to increased cell stress, apoptotic signaling and disassociation of melanin aggregates. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the present study was to determine the effects of harmane, norharmane and harmine on the immobility time in the mouse forced swim test (FST) — an animal model of depression. After 30 min of the β-carbolines injections, mice were placed individually in a vertical glass cylinder (height, 25 cm; diameter, 12 cm) containing water about 15 cm deep at 22±1 °C and forced to swim. Treatment of animals with harmane (5–15 mg/kg, i.p.), norharmane (2.5–10 mg/kg, i.p.) and harmine (5–15 mg/kg, i.p.) reduced dose-dependently the time of immobility. Their antidepressant-like effects were not affected by pretreatment with reserpine at the dose of 5 mg/kg, i.p., 18 h before the test, which did not modify the immobility time. Conversely, when flumazenil (5 mg/kg, i.p.) was administered 30 min before the test, it was able to antagonize completely the antidepressant-like effects of harmane, norharmane and harmine. It was concluded that harmane, norharmane and harmine reduce the immobility time in this test, suggesting an antidepressant-like effect, via an inverse-agonistic mechanism located in the benzodiazepine receptors. [Copyright &y& Elsevier]

The β-carboline norharman is present in cooked food and tobacco smoke and show structural resemblance to the neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. C57BL/6 mice were injected subcutaneously with norharman (3 and 10 mg/kg) twice per day for five consecutive days. Eighteen hours after the last dose an increased expression of glial fibrillary acidic protein and fluoro-jade staining were demonstrated whereas the number of tyrosine hydroxylase positive cells were unchanged in the substantia nigra. Two weeks after the last treatment a decreased motor activity was observed whereas cognitive functions remained intact. In cultured PC12 cells norharman treatment induced mitochondrial dysfunction and increased the number of caspase-3 and TUNEL-positive cells. The results demonstrate that norharman induced apoptosis in cultured cells as well as early neurodegeneration, glial activation and sustained motor deficits in mice and suggest that exposure to norharman may contribute to idiopathic Parkinson’s disease. [ABSTRACT FROM AUTHOR]

Abstract: Monoamine oxidase (MAO) is a mitochondrial outer-membrane flavoenzyme involved in brain and peripheral oxidative catabolism of neurotransmitters and xenobiotic amines, including neurotoxic amines, and a well-known target for antidepressant and neuroprotective drugs. Recent epidemiological studies have consistently shown that coffee drinkers have an apparently lower incidence of Parkinson''s disease (PD), suggesting that coffee might somehow act as a purported neuroprotectant. In this paper, “ready to drink” coffee brews exhibited inhibitory properties on recombinant human MAO A and B isozymes catalyzing the oxidative deamination of kynuramine, suggesting that coffee contains compounds acting as MAO inhibitors. MAO inhibition was reversible and competitive for MAO A and MAO B. Subsequently, the pyrido-indole (β-carboline) alkaloids, norharman and harman, were identified and isolated from MAO-inhibiting coffee, and were good inhibitors on MAO A (harman and norharman) and MAO B (norharman) isozymes. β-carbolines isolated from ready-to-drink coffee were competitive and reversible inhibitors and appeared up to 210 μg/L, confirming that coffee is the most important exogenous source of these alkaloids in addition to cigarette smoking. Inhibition of MAO enzymes by coffee and the presence of MAO inhibitors that are also neuroactive, such as β-carbolines and eventually others, might play a role in the neuroactive actions including a purported neuroprotection associated with coffee consumption. [Copyright &y& Elsevier]

Abstract: This study was designed to determine the affinity and binding profile of β-carbolines for imidazoline I2 receptors and catalytic sites of monoamine oxidase (MAO)-A/B in rat brain and liver. The aim was also directed to assess the in vivo effects of norharman (β-carboline) and LSL 60101 (I2 ligand) on brain 3,4-dihydroxyphenylalanine (DOPA) synthesis in morphine-dependent rats. Competition experiments against [3H]2-BFI revealed that β-carbolines recognize the high- and low-affinity components of the brain imidazoline I2 receptor with the rank order of potency (K iH in nM): noreleagnine (12)>norharman (20)>harmalol (82)>harmaline (177)≫harmine (630)>harman (700)≫FG-7142 (>100,000). In liver, this rank was different: harmine (51)>harmaline (103)=noreleagnine (103)≫harmalol (1290)>harman (2000)≫norharman (12,382)≫FG-7142 (>100,000). In brain and liver, competition curves for β-carbolines against [3H]Ro41-1049 (MAO-A) and [3H]Ro19-6327 (MAO-B) were monophasic and resulted in different drug potencies for the two MAO isozymes (higher affinities for MAO-A) and in similar pharmacological profiles in both tissues. In morphine-dependent rats, naloxone (2 mg/kg, 2 h)-precipitated withdrawal increased the synthesis of DOPA in the cerebral cortex and hippocampus (50%). Pretreatment with norharman (20 mg/kg) or LSL 60101 (20 mg/kg) (30 min before naloxone) fully prevented the stimulatory effect of opiate withdrawal on DOPA synthesis. Norharman and LSL 60101 also attenuated the severity of the withdrawal syndrome. The results indicate that β-carbolines bind with high affinity to imidazoline I2B receptors, and similarly to I2 ligands (LSL 60101) can block the behavioural and biochemical effects of opiate withdrawal. [Copyright &y& Elsevier]

The aim of this study was to investigate the role of the endogenous substance norharman in processes of alcohol and nicotine or tobacco dependence in both humans and animals. For this purpose heavy smokers and excessive alcohol drinkers were recruited, and rats were made dependent on alcohol and nicotine. Plasma concentrations of norharman were measured in drug-naïve, drug-free and drug-taking situations. In addition, craving and nicotine dependence were measured in the group of heavy smokers, while in the animal studies the effect of exogenously administered norharman on the behavioural signs of alcohol and nicotine withdrawal were determined. Humans who abstained from smoking and drinking for a period of 12?h showed normal plasma levels of norharman. Resumption of smoking, but not drinking, generated elevated plasma levels of norharman, especially after smoking self-made non-filter cigarettes. Although craving after a period of abstinence was stronger in smokers with high tobacco dependence compared to those with low dependence, the plasma levels of norharman were only negatively related to craving among low nicotine-dependent smokers. From the animal experiments it was concluded that nicotine intake had no effect on plasma levels of norharman. On the other hand, withdrawal symptoms elicited in nicotine-dependent rats could be attenuated by exogenous administration of norharman. Rats made alcohol-dependent by forced intake of an ethanol-containing diet showed higher norharman levels in plasma and brain compared to alcohol-naïve rats. This increase is caused by a lower clearance of norharman by the liver of alcohol-fed rats. After stopping alcohol intake, behavioural signs of alcohol withdrawal occurred which were inhibited by pretreatment with norharman. The results indicate that norharman is involved in processes of alcohol and tobacco dependence and that this substance may be a candidate adjuvant in alleviating abstinence symptoms. [ABSTRACT FROM AUTHOR]

Abstract: Monoamine oxidase (MAO) is a mitochondrial outer-membrane flavoenzyme involved in brain and peripheral oxidative catabolism of neurotransmitters and xenobiotic amines, including neurotoxic amines, and a well-known target for antidepressant and neuroprotective drugs. Recently, positron emission tomography imaging has shown that smokers have a much lower activity of peripheral and brain MAO-A (30%) and -B (40%) isozymes compared to non-smokers. This MAO inhibition results from a pharmacological effect of smoke, but little is known about its mechanism. Working with mainstream smoke collected from commercial cigarettes we confirmed that cigarette smoke is a potent inhibitor of human MAO-A and -B isozymes. MAO inhibition was partly reversible, competitive for MAO-A, and a mixed-type inhibition for MAO-B. Two β-carboline alkaloids, norharman (β-carboline) and harman (1-methyl-β-carboline), were identified by GC–MS, quantified, and isolated from the mainstream smoke by solid phase extraction and HPLC. Kinetics analysis revealed that β-carbolines from cigarette smoke were competitive, reversible, and potent inhibitors of MAO enzymes. Norharman was an inhibitor of MAO-A (Ki=1.2±0.18μM) and MAO-B (Ki=1.12±0.19μM), and harman of MAO-A (Ki=55.54±5.3nM). β-Carboline alkaloids are psychopharmacologically active compounds that may occur endogenously in human tissues, including the brain. These results suggest that β-carboline alkaloids from cigarette smoke acting as potent reversible inhibitors of MAO enzymes may contribute to the MAO-reduced activity produced by tobacco smoke in smokers. The presence of MAO inhibitors in smoke like β-carbolines and others may help us to understand some of the purported neuropharmacological effects associated with smoking. [Copyright &y& Elsevier]

Norharman and harman are two heterocyclic β-carboline (9 H -pyrido[3,4-b]indole) alkaloids with biological and potential toxicological activity that appear in foodstuffs and environmental sources. To assess the occurrence and distribution of these compounds and to estimate the exposure levels based on the detected amounts, numerous samples of foodstuffs and cigarette smoke were analysed by solid-phase extraction and high-performance liquid chromatography-fluorescence. The levels found of β-carbolines were highly variable. Low processed foodstuffs (i.e. milk, yoghurt, uncooked meats and fish) did not contain norharman and harman above the detection limit. Others, however, contained relatively high concentrations (at the tens of ng g -1 or μg l -1 level) depending on the processing conditions as, for example, 'well-done' cooked meat and fish. The highest amounts of norharman and harman were found in brewed coffee (29-207 μg l -1 ), sauces (soy sauce and Tabasco, among others; 4-252 μg l -1 ), 'well done' cooked meat and fish (57-160 ng g -1 ), toasted bread (42-160 ng g -1 ), and fermented alcoholic beverages (n.d.-41 μg l -1 ). β-Carbolines also occurred in a high amount in the mainstream of cigarette smoke (207-2780 ng/cigarette), which is an important contributor to daily exposure to these compounds. Based on these results, it is concluded that the daily exposure to β-carbolines in humans might be from tens to hundreds of micrograms, with cigarette smoke, coffee, certain seasonings, cooked foods and alcoholic beverages, in this order, being the major contributors. Many other foodstuffs might also contribute with minor amounts of norharman and harman. Foods and tobacco smoke might be potential contributors to the reported endogenous presence of β-carbolines in humans. [ABSTRACT FROM AUTHOR]

We examined the effects of ethanol ingestion to rats on levels of the β-carboline norharman in plasma, brain and liver at the end of ethanol ingestion and 10 h after withdrawal. We also investigated the effect of exogenously administered norharman on the behavioural signs of alcohol withdrawal. Ethanol was given by a liquid diet for 21 days. Norharman plasma levels in alcohol fed rats were significantly elevated compared to both control rats and to rats 10 h after withdrawal. Norharman levels in brains and livers showed a similar pattern. The capacity of the livers of both alcohol-dependent and withdrawal rats to catabolise norharman was significantly reduced compared to control rats. Norharman injected intraperitoneally (6.3 mg/kg) attenuated the behavioural signs of alcohol withdrawal significantly. The mechanism behind the increased norharman levels in alcohol-dependent rats may be inhibition of the synthesis and/or activity of liver enzyme(s) responsible for the breakdown of norharman. [Copyright &y& Elsevier]

Mutagenic 9-(4′-aminophenyl)-9H-pyrido[3,4-b]indole (aminophenylnorharman, APNH), formed from norharman and aniline in the presence of S9 mix, is thought to be accountable for the co-mutagenic action of norharman. Our previous studies suggest that cytochrome P-450s (CYPs) are involved in the generation of APNH. In order to identify the responsible CYP species in the present study, norharman (8 mg) and aniline (4 mg) were incubated with individual recombinant human CYPs (2 nmol) at 37 °C for 20 min. Formation of APNH was observed with CYP1A1, CYP1A2, CYP1B1, CYP2B6, CYP2D6, CYP2E1 and CYP3A4, but not with CYP2A6, CYP2C9 and CYP2C19. The amounts of APNH from norharman and aniline were 33 ng for CYP1A1, 15 ng for CYP3A4, 7 ng for CYP2D6, 6 ng for CYP1A2 and 5 ng for CYP2B6. APNH formation in the presence of CYP1B1 and CYP2E1 was very low at around one fiftieth of that with CYP3A4. When CYP selective chemical inhibitors, such as furafylline for CYP1A2 and ketoconazole for CYP3A4, were added to the reaction mixture of norharman, aniline and human microsomes, formation of APNH was decreased to 14 and 16% of the control level, respectively. Moreover, human lung microsomes also showed the activity of APNH formation from norharman and aniline, albeit at only one hundredth of that with liver microsomes. In general, content in human liver microsomes is rather high for CYP3A4 and CYP1A2 but relatively low for CYP2D6 and CYP2B6, at about 30, 10, 1.5% and less than 1% of the total CYP, respectively. Although CYP1A1 showed the highest APNH formation activity, its expression in human liver is reported to be below the level of detection. Based on these observations, it is suggested that the practical major contributors to the formation of APNH from norharman and aniline are CYP3A4 and CYP1A2, the responsible reactions mainly occurring in the liver. [Copyright &y& Elsevier]