Effect of Chemical Refining on the Reduction of ß-Carboline Content in Sesame Seed Oil.

ß-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 ß-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. ß-carbolines are nonpolar heterocyclic aromatic amines with good solubility in leaching solvents (n-hexane); therefore, the ß-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 ß-carboline content during the refining of leaching sesame seed oil and the key process steps for the removal of ß-carbolines. In this work, the levels of ß-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 ß-carbolines greatly decreased, and the adsorption decolorization was the most effective process in reducing ß-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 ß-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 ß-carbolines.

Identification of Compounds with Potential Therapeutic Uses from Sweet Pepper (Capsicum annuum L.) Fruits and Their Modulation by Nitric Oxide (NO).

Plant species are precursors of a wide variety of secondary metabolites that, besides being useful for themselves, can also be used by humans for their consumption and economic benefit. Pepper (Capsicum annuum L.) fruit is not only a common food and spice source, it also stands out for containing high amounts of antioxidants (such as vitamins C and A), polyphenols and capsaicinoids. Particular attention has been paid to capsaicin, whose anti-inflammatory, antiproliferative and analgesic activities have been reported in the literature. Due to the potential interest in pepper metabolites for human use, in this project, we carried out an investigation to identify new bioactive compounds of this crop. To achieve this, we applied a metabolomic approach, using an HPLC (high-performance liquid chromatography) separative technique coupled to metabolite identification by high resolution mass spectrometry (HRMS). After chromatographic analysis and data processing against metabolic databases, 12 differential bioactive compounds were identified in sweet pepper fruits, including quercetin and its derivatives, L-tryptophan, phytosphingosin, FAD, gingerglycolipid A, tetrahydropentoxylin, blumenol C glucoside, colnelenic acid and capsoside A. The abundance of these metabolites varied depending on the ripening stage of the fruits, either immature green or ripe red. We also studied the variation of these 12 metabolites upon treatment with exogenous nitric oxide (NO), a free radical gas involved in a good number of physiological processes in higher plants such as germination, growth, flowering, senescence, and fruit ripening, among others. Overall, it was found that the content of the analyzed metabolites depended on the ripening stage and on the presence of NO. The metabolic pattern followed by quercetin and its derivatives, as a consequence of the ripening stage and NO treatment, was also corroborated by transcriptomic analysis of genes involved in the synthesis of these compounds. This opens new research perspectives on the pepper fruit's bioactive compounds with nutraceutical potentiality, where biotechnological strategies can be applied for optimizing the level of these beneficial compounds.

LC/MS analysis of three-dimensional model cells exposed to cigarette smoke or aerosol from a novel tobacco vapor product.

A novel tobacco vapor product (NTV) contains tobacco leaves and generates nicotine-containing aerosols using heating elements. Subchronic biological effects have been evaluated previously using three-dimensional bronchial epithelial model cells by repeated exposure to cigarette smoke (CS) and the NTV aerosols; however, the intracellular exposure characteristics have not been studied in detail. In this study, cells were initially exposed to an aqueous extract (AqE) of cigarette smoke (CS) at two concentration levels, and the cell lysate underwent untargeted analysis by LC-high resolution mass spectrometry to determine the exogenous compounds present in the cells. Among the thousands of peaks detected, four peaks showed a CS-dependency, which were reproducibly detected. Two of the peaks were nicotine and nicotine N-oxide, and the other two putative compounds were myosmine and norharman. The cells were then exposed to an AqE of CS in various combinations of exposure and post-exposure culture durations. Post-exposure culturing of cells with fresh medium markedly decreased the peak areas of the four compounds. The in-vitro switching study of CS to NTV aerosols was investigated by intermittently exposing cells to an AqE of CS four times, followed by exposure to either an AqE of CS, NTV aerosol or medium another four times. Switching to NTV reduced myosmine and norharman levels, which are known CS constituents. The results indicate that extracellular compounds inside cells reflect the exposure state outside cells. Thus, monitoring functional changes to cells in these exposure experiments is feasible.

Biosynthesis-inspired mining and identification of untapped alkaloids in Camptotheca acuminate for enzyme discovery using ultra-high performance liquid chromatography coupled with quadrupole-time of flight-mass spectrometry.

Leaves, flowers, fruits and stems (44 sample groups) were collected from mature Camptotheca acuminate during 2017.3-2018.3 and classified by ultra-high performance liquid chromatography coupled with quadrupole-time of flight-mass spectrometry based metabolomics. One hundred metabolites including forty-seven alkaloids, fifteen terpenes, thirty-two polyphenols and six other metabolites were rapidly identified through the in-house database alignment at first glance. Thirty-three alkaloids classified into five groups including camptothecin group (CG1-13), pumiloside group (PG1-5), strictosidinic acid group (SG1-3), vincosamide group (VG1-7), and a new hybrid group, vincosamide-camptothecin group (VC1-5) were mined and further characterized by MS/MS analyses. The identification of two untapped biosynthetic precursors, 2-hydroxypumiloside (PG2) and 16­hydroxy­15, 16-dihydrocamptothecoside (CG3), along with sixteen new alkaloids enables us for a better understanding of camptothecin biogenetic reasoning. The underlying enzymes involved in camptothecin biosynthesis were also proposed according to the guiding metabolic map, thus purposefully mining of enzymes involved in the downstream biosynthetic pathway of camptothecin could be initiated with the help of this map.

Cooking with elaborate recipes can reduce the formation of mutagenic heterocyclic amines and promote co-mutagenic amines.

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.

Development and validation of a liquid chromatography-tandem mass spectrometry assay for the quantification of lurbinectedin in human plasma and urine.

Lurbinectedin is a novel highly selective inhibitor of RNA polymerase II triggering caspase-dependent apoptosis of cancerous cells. This article describes the development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to quantify lurbinectedin in human plasma and urine. Plasma samples were pre-treated with 1 M aqueous ammonia after which they were brought onto supported liquid extraction (SLE) columns. Lurbinectedin was eluted from the columns using tert-butyl methyl ether (TBME). Urine was first diluted in plasma and lurbinectedin was extracted from this matrix by liquid-liquid extraction using TBME. Samples were measured by LC-MS/MS in the positive electron ion spray mode. The method was linear over 0.1-100 ng/mL and 1-1000 ng/mL in plasma and urine, respectively, with accuracies and precisions within ±15% (20% for LLOQ) and below 15% (20% for LLOQ), respectively. The method was developed to support a mass balance study in which patients received a dose of 5 mg lurbinectedin.

Screening and identification of the main metabolites of 2-amino-9H-pyrido[2,3-b]indole (AαC) in liver microsomes and rat urine by using UPLC-Q-TOF-MS/MS.

2-Amino-9H-pyrido[2,3-b]indole (AαC), which has been reported to be 40-258ng per cigarette, was regarded as a probable human carcinogen (Group 2B) and harmful composition in Hoffman list. Thus, it is of great significance to develop an effective method for the accurate identification of AαC and its metabolites. In the present study, we have investigated for the first time the in vivo and in vitro metabolites of AαC using ultra performance liquid chromatography combined with diode array detector and time-of-flight mass spectrometry (UPLC-DAD and UPLC-Q-TOF-MS/MS). A comparative study showed that the metabolic patterns of AαC in beagle, mouse, rat and human liver microsomes were of significant difference with these in rat urine. For the metabolism of AαC in liver microsomes, nine metabolites of AαC, including five hydroxy metabolites, two quinone metabolites and two N-dimer metabolites, have been found. However, metabolism of AαC in rats is a phase II process with complex enzyme catalysis, 23 metabolites including C- and N-oxidation, O- and N-glycosylation, O- and N-sulfonation, and N-acetylation were identified in rat urine. In addition, five new N-acetyl-AαC-OH metabolites were identified for the first time, indicating a possible new pathway for the metabolism. This study significantly enriched our knowledge about the metabolism of AαC, and will be useful for a better understanding of its harmfulness and toxicity.

Slow-release L-cysteine capsule prevents gastric mucosa exposure to carcinogenic acetaldehyde: results of a randomised single-blinded, cross-over study of Helicobacter-associated atrophic gastritis.

INTRODUCTION: Helicobacter-induced atrophic gastritis with a hypochlorhydric milieu is a risk factor for gastric cancer. Microbes colonising acid-free stomach oxidise ethanol to acetaldehyde, a recognised group 1 carcinogen. OBJECTIVE: To assess gastric production of acetaldehyde and its inert condensation product, non-toxic 2-methyl-1,3-thiazolidine-4-carboxylic acid (MTCA), after alcohol intake under treatment with slow-release L-cysteine or placebo. METHODS: Seven patients with biopsy-confirmed atrophic gastritis, low serum pepsinogen and high gastrin-17 were studied in a cross-over single-blinded design. On separate days, patients randomly received 200 mg slow-release L-cysteine or placebo with intragastric instillation of 15% (0.3 g/kg) ethanol. After intake, gastric concentrations of ethanol, acetaldehyde, L-cysteine and MTCA were analysed. RESULTS: Administration of L-cysteine increased MTCA (p < .0004) and decreased gastric acetaldehyde concentrations by 68% (p < .0001). The peak L-cysteine level was 7552 ± 2687 µmol/L at 40 min and peak MTCA level 196 ± 98 µmol/L at 80 min after intake. Gastric L-cysteine and MTCA concentrations were maintained for 3 h. The AUC for MTCA was 11-fold higher than acetaldehyde, indicating gastric first-pass metabolism of ethanol. With placebo, acetaldehyde remained elevated also at low ethanol concentrations representing 'non-alcoholic' beverages and food items. CONCLUSIONS: After gastric ethanol instillation, slow-release L-cysteine eliminates acetaldehyde to form inactive MTCA, which remains in gastric juice for up to 3 h. High acetaldehyde levels indicate a marked gastric first-pass metabolism of ethanol resulting in gastric accumulation of carcinogenic acetaldehyde. Local exposure of the gastric mucosa to acetaldehyde can be mitigated by slow-release L-cysteine capsules.

Identification of anti-cancer chemical compounds using Xenopus embryos.

Cancer tissues have biological characteristics similar to those observed in embryos during development. Many types of cancer cells acquire pro-invasive ability through epithelial-mesenchymal transition (EMT). Similar processes (gastrulation and migration of cranial neural crest cells [CNCC]) are observed in the early stages of embryonic development in Xenopus during which cells that originate from epithelial sheets through EMT migrate to their final destinations. The present study examined Xenopus embryonic tissues to identify anti-cancer compounds that prevent cancer invasion. From the initial test of known anti-cancer drugs, AMD3100 (an inhibitor of CXCR4) and paclitaxel (a cytoskeletal drug targeting microtubules) effectively prevented migration during gastrulation or CNCC development. Blind-screening of 100 synthesized chemical compounds was performed, and nine candidates that inhibited migration of these embryonic tissues without embryonic lethality were selected. Of these, C-157 (an analog of podophyllotoxin) and D-572 (which is an indole alkaroid) prevented cancer cell invasion through disruption of interphase microtubules. In addition, these compounds affected progression of mitotic phase and induced apoptosis of SAS oral cancer cells. SAS tumors were reduced in size after intratumoral injection of C-157, and peritoneal dissemination of melanoma cells and intracranial invasion of glioma cells were inhibited by C-157 and D-572. When the other analogues of these chemicals were compared, those with subtle effect on embryos were not tumor suppressive. These results suggest that a novel chemical-screening approach based on Xenopus embryos is an effective method for isolating anti-cancer drugs and, in particular, targeting cancer cell invasion and proliferation.

Norharmane rhenium(I) polypyridyl complexes: synthesis, structural and spectroscopic characterization.

Two novel Re(i) complexes with the general formula fac-[Re(CO)3(L)(nHo)]CF3SO3, where L = 2,2'-bipyridine (bpy) or 1,10 phenanthroline (phen) and nHo (9H-pyrido[3,4-b]indole; norharmane) have been synthesized. The Re(i)-nHo complexes were characterized by structural X-ray diffraction, (1)H and (13)C NMR, UV-vis absorption and FT-IR spectroscopy, and by a combination of two mass spectrometry techniques, namely ESI-MS and UV-MALDI-MS. All characterizations showed that nHo is coordinated to the metal atom by the pyridine nitrogen of the molecule. X-ray structural analysis revealed that the crystal lattices for both complexes are further stabilized by a strong >N-HO bond between the pyrrole NH group of the pyridoindole ligand and one oxygen atom of the trifluoromethanesulfonate counter-ion. Ground state geometry optimization by DFT calculations showed that in fluid solution the nHo ligand may rotate freely. The nature of the electronic transitions of Re(CO)3(bpy)(nHo)(+) were established by TD-DFT calculations. The set of the most important electronic transitions present in this complex are comprised of π→π* electronic transitions centered on bpy and nHo moieties, LLCTnHo→COs, MLLCTRe(CO)3→bpy and LLCTnHo→bpy transitions. Additionally, TD-DFT calculations predict the existence of another two intense MLLCTRe(CO)3→nHo electronic transitions. Calculated UV-vis absorption spectra are in good agreement with the corresponding experimental data for the bpy-containing complex.

Isolation, purification and identification of antioxidants in an aqueous aged garlic extract.

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-ß-carboline-3-carboxylic acid, (1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid, and (1R,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid as the major antioxidants in the AGE. The EC50 values of these purified tetrahydro-ß-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-ß-carboline-3-carboxylic acid as an in vitro antioxidant in AGE.

Chromatographic analysis of some drugs employed in erectile dysfunction therapy: qualitative and quantitative studies using calixarene stationary phase.

In this study, the effect of change in chromatographic process variables on the retention behavior of four drugs employed in erectile dysfunction therapy on a calixarene stationary phase is described. Three of these drugs are known to treat erectile dysfunction, namely, sildenafil citrate, tadalafil, and apomorphine hydrochloride, and one drug that is used as opioid analgesic, tramadol hydrochloride, which is quiet widely misused to treat premature ejaculation. The results indicate the importance of considering the structure and pKa values of drugs to be separated along with mobile phase composition. A new optimized, rapid, and accurate liquid chromatography method is also established for simultaneous determination of sildenafil citrate, tadalafil, and apomorphine hydrochloride in pharmaceutical preparations and bulk powders. The chromatographic separation of the three pharmaceuticals was achieved on a calixarene column in less than 10 min using a binary mobile phase of 35% acetonitrile and 65% 50 mM sodium perchlorate pH2.5 at 1 mL/min flow rate. The method was validated for system efficiency, linearity, accuracy, precision, limits of detection and quantitation, specificity, stability, and robustness. Statistical analysis proved that the method enabled reproducible and selective quantification of all three analytes in bulk drugs and in pharmaceutical preparations.

Headspace-gas chromatographic fingerprints to discriminate and classify counterfeit medicines.

Counterfeit medicines are a global threat to public health. These pharmaceuticals are not subjected to quality control and therefore their safety, quality and efficacy cannot be guaranteed. Today, the safety evaluation of counterfeit medicines is mainly based on the identification and quantification of the active substances present. However, the analysis of potential toxic secondary components, like residual solvents, becomes more important. Assessment of residual solvent content and chemometric analysis of fingerprints might be useful in the discrimination between genuine and counterfeit pharmaceuticals. Moreover, the fingerprint approach might also contribute in the evaluation of the health risks different types of counterfeit medicines pose. In this study a number of genuine and counterfeit Viagra(®) and Cialis(®) samples were analyzed for residual solvent content using headspace-GC-MS. The obtained chromatograms were used as fingerprints and analyzed using different chemometric techniques: Principal Component Analysis, Projection Pursuit, Classification and Regression Trees and Soft Independent Modelling of Class Analogy. It was tested whether these techniques can distinguish genuine pharmaceuticals from counterfeit ones and if distinct types of counterfeits could be differentiated based on health risks. This chemometric analysis showed that for both data sets PCA clearly discriminated between genuine and counterfeit drugs, and SIMCA generated the best predictive models. This technique not only resulted in a 100% correct classification rate for the discrimination between genuine and counterfeit medicines, the classification of the counterfeit samples was also superior compared to CART. This study shows that chemometric analysis of headspace-GC impurity fingerprints allows to distinguish between genuine and counterfeit medicines and to differentiate between groups of counterfeit products based on the public health risks they pose.

A review on medicinal importance, pharmacological activity and bioanalytical aspects of beta-carboline alkaloid ''Harmine''.

Harmine, a beta-carboline alkaloid, is widely distributed in the plants, marine creatures, insects, mammalians as well as in human tissues and body fluids. Harmine was originally isolated from seeds of Peganum harmal in 1847 having a core indole structure and a pyridine ring. Harmine has various types of pharmacological activities such as antimicrobial, antifungal, antitumor, cytotoxic, antiplasmodial, antioxidaant, antimutagenic, antigenotoxic and hallucinogenic properties. It acts on gamma-aminobutyric acid type A and monoamine oxidase A or B receptor, enhances insulin sensitivity and also produces vasorelaxant effect. Harmine prevents bone loss by suppressing osteoclastogenesis. The current review gives an overview on pharmacological activity and analytical techniques of harmine, which may be useful for researcheres to explore the hidden potential of harmine and and will also help in developing new drugs for the treatment of various diseases.

Identification of amino-tadalafil and rimonabant in electronic cigarette products using high pressure liquid chromatography with diode array and tandem mass spectrometric detection.

A high-pressure liquid chromatography-diode array detection and multi-mode ionization tandem mass spectrometry (HPLC-DAD-MMI-MS/MS) method was used to identify amino-tadalafil and rimonabant in electronic cigarette (e-cigarette) cartridges. Amino-tadalafil is a drug analogue of the commercially approved Cialis™ (i.e. tadalafil). Rimonabant is a drug that was, at one time, approved for weight loss in Europe (although approval has been retracted), but not in the United States. In addition, poor quality control over the e-cigarette products analyzed here is shown by the presence of nicotine in products labeled as containing no nicotine or by the presence of significant amounts of rimonabant oxidative degradant in e-cigarette products containing rimonabant. Identification was accomplished by comparing the retention time of relevant peaks in the sample with those of standard compounds, in addition to comparison of the UV spectra, mass spectra and/or product ion mass spectra.

Electrospray MS-based characterization of beta-carbolines--mutagenic constituents of thermally processed meat.

The beta-carbolines 1-methyl-9H-pyrido [3,4-b]indole and 9H-pyrido[3,4b]indole have been implicated as having causative roles in a number of human diseases, such as Parkinson's disease and cancer. As they can be formed during the heating of protein-rich food, a number of analytical methodologies have been proposed for their detection and quantification in foodstuff. For this purpose, LC-MS and LC-MS/MS have emerged as the most specific analytical methods, and the quantification is based on the occurrence of unusual ions, such as [M+H-(H(*))]+ and [M+H-2H]+. In this study, we have investigated the formation of these ions by accurate-mass electrospray MS/MS and demonstrated that these ions are formed from gas-phase ion-molecule reactions between water vapor present in the collision cell and the protonated molecule of 1-methyl-9H-pyrido [3,4-b]indole and 9H-pyrido[3,4b]indole. Although this reaction has been previously described for heterocyclic amine ions, it has been overlooked in the most of recent LC-MS and LC-MS/MS studies, and no complete data of the fragmentation are reported. Our results demonstrate that additional attention should be given with respect to eliminating water vapor residues in the mass spectrometer when analysis of beta-carbolines is performed, as this residue may affect the reliability in the results of quantification.

Identification of sildenafil, tadalafil and vardenafil by gas chromatography-mass spectrometry on short capillary column.

Sildenafil and its analogues (tadalafil and vardenafil) are phosphodiesterase type 5 inhibitors used in the treatment of male erectile dysfunction. Some dietary supplements, herbal preparations and food products which claim to enhance male sexual function have been found to be adulterated with these drugs. In this study, a gas chromatograph-mass spectrometer (GC-MS) assay was developed for identification of the drugs. In addition to good and short chromatographic separation that can be achieved within 6 min by using a short 10 m capillary column, no prior sample clean-up before GC-MS analysis was required, thus making this assay a cost saving and rapid method. Furthermore, the assay is specific as the identification of sildenafil, tadalafil and vardenafil were done by detection of molecular ions; m/z 474, 389 and 488, [corrected] respectively, and several other characteristic ions resulted from the mass fragmentation of individual molecules. Using our currently developed assay, sildenafil and its analogues were successfully identified in food and herbal matrices.

Analysis of heterocyclic amines and beta-carbolines by liquid chromatography-mass spectrometry in cooked meats commonly consumed in Korea.

Heterocyclic amines (HAs), which form in meats during heating and cooking, are recognized as mutagenic and carcinogenic compounds. In this study, 13 HAs and 2 beta-carbolines (BCs) were analyzed in cooked Korean meat products, including griddled bacon, griddled pork loin, boiled pork loin, boiled chicken meat, chicken meat stock, chicken breast for salad and chicken patty. The samples were either cooked in the laboratory or purchased from local fast-food restaurants. The HAs and BCs in the samples were separated using solid-phase extraction and were analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS). The most frequently detected HAs and BCs in the cooked meats were harman (1-methyl-9H pyrido[4,3-b]indole; 990.9 ng g(-1)), norharman (9H-pyrido[4,3-b]indole; 412.7 ng g(-1)) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine; 258.2 ng g(-1)). The griddled pork loin and bacon contained higher levels of norharman, harman and PhIP than the other cooked meats. PhIP, which is classified as a Group 2B carcinogen by the International Agency for Research on Cancer, had levels of 258.2 and 168.2 ng g(-1) in the griddled pork loin and griddled bacon, respectively. The griddled bacon was the only sample containing TriMeIQx (2-amino-3,4,7,8-tetramethylimidazo[4,5-f]quinoxaline; 79.9 ng g(-1)). IQ (2-amino-3-methyl imidazo[4,5-f]quinoline), 7,8-DiMeIQx (2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline), 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline) and AalphaC (2-amino-9H-pyrido[2,3-b]indole) were detected at trace levels in all samples.

Gas chromatographic analysis of dimethyltryptamine and beta-carboline alkaloids in ayahuasca, an Amazonian psychoactive plant beverage.

INTRODUCTION: Ayahuasca is obtained by infusing the pounded stems of Banisteriopsis caapi in combination with the leaves of Psychotria viridis. P. viridis is rich in the psychedelic indole N,N-dimethyltryptamine, whereas B. caapi contains substantial amounts of beta-carboline alkaloids, mainly harmine, harmaline and tetrahydroharmine, which are monoamine-oxidase inhibitors. Because of differences in composition in ayahuasca preparations, a method to measure their main active constituents is needed. OBJECTIVE: To develop a gas chromatographic method for the simultaneous determination of dimethyltryptamine and the main beta-carbolines found in ayahuasca preparations. METHODOLOGY: The alkaloids were extracted by means of solid phase extraction (C(18)) and detected by gas chromatography with nitrogen/phosphorous detector. RESULTS: The lower limit of quantification (LLOQ) was 0.02 mg/mL for all analytes. The calibration curves were linear over a concentration range of 0.02-4.0 mg/mL (r(2 )> 0.99). The method was also precise (RSD < 10%). CONCLUSION: A simple gas chromatographic method to determine the main alkaloids found in ayahuasca was developed and validated. The method can be useful to estimate administered doses in animals and humans for further pharmacological and toxicological investigations of ayahuasca.

Tobacco smoking and urinary levels of 2-amino-9H-pyrido[2,3-b]indole in men of Shanghai, China.

Carcinogenic heterocyclic aromatic amines (HAA) are formed in cooked meats, poultry, and fish and arise in tobacco smoke. We measured the concentrations of four prevalent HAAs in spot urine samples collected at baseline from 170 participants of the Shanghai Cohort study, a population-based cohort study of adult men recruited during 1986 to 1989 in Shanghai, China. Sixteen (18.6%) of 86 nonsmokers were positive for urinary 2-amino-9H-pyrido[2,3-b]indole (AalphaC) versus 41 (48.8%) of 84 cigarette smokers; the difference was statistically significant (P < 0.001). The number of cigarettes smoked per day was positively and significantly related to urinary levels of AalphaC in study subjects (P < 0.001); the mean level among nonsmokers was 2.54 ng/g creatinine, whereas the means for light (1-19 cigarettes per day) and heavy (20+ cigarettes per day) smokers were 7.50 and 11.92 ng/g creatinine, respectively. 2-Amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline was undetected in the urine of the 170 subjects. Only 5 (2.9%) and 6 (3.5%) subjects, respectively, showed detectable levels of urinary 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, and smoking status was unrelated to levels of either HAA. Quantitative measurements of HAAs in commonly eaten pork and chicken dishes in Shanghai showed low concentrations of HAAs (<1 ng/g meat). Our data indicate that AalphaC represents a major HAA exposure in adult men of Shanghai, China, and that tobacco smoke is an important point source of their AalphaC exposure.