International journal of tryptophan research : IJTR最新文献

{"title":"Activation of the Kynurenine Pathway and Production of Inflammatory Cytokines by Astrocytes and Microglia Infected With <i>Neospora caninum</i>.","authors":"Deivison Silva Argolo,&nbsp;Julita Maria Pereira Borges,&nbsp;Luciana Dos Santos Freitas,&nbsp;Gizelle Alves Pina,&nbsp;Maria Socorro Grangeiro,&nbsp;Victor Diógenes Amaral da Silva,&nbsp;Alexandre Moraes Pinheiro,&nbsp;Rodrigo Souza Conceição,&nbsp;Alexsandro Branco,&nbsp;Gilles Guillemin,&nbsp;Silvia Lima Costa,&nbsp;Maria de Fátima Dias Costa","doi":"10.1177/11786469211069946","DOIUrl":"https://doi.org/10.1177/11786469211069946","url":null,"abstract":"<p><p>In the central nervous system, astrocytes and microglia contribute to homeostasis, regulating the immune response to infectious agents. <i>Neospora caninum</i> is an obligate intracellular protozoan that infects different animal species and it is encysted in their nervous tissue while triggering an immune response modulated by glia. This study aimed to evaluate the infection of primary cultures of rat glial cells by <i>N. caninum</i> through the catabolites of tryptophan, the expression of inflammatory mediators and the integrity of neural tissue. Infection with this coccidium resulted in morphological and functional changes, particularly astrogliosis and microgliosis, and increased the expression of the inflammatory mediators TNF, IL1β, IL-10, and arginase, as well as mRNA for CCL5 and CCL2, molecules involved in the CNS chemotaxis. The infection with <i>N. caninum</i> in glial cells also triggered the activation of the tryptophan pathway, characterized by increased kynurenine 2,3 monooxygenase (KMO) mRNA expression, and by the production of the excitotoxin quinolinic acid (QUIN). Moreover, glia-neuron co-cultures, when exposed to the secretome derived from <i>N. caninum</i> infected glial cells, presented greater neurons distribution and formation of neurite extensions, associated to morphological changes in astrocytes compatible with neuro-preservation. Considering that the tryptophan catabolism is associated to immune response, these findings suggest that glial activation in <i>N. caninum</i> infection should be responsible for modulating the inflammatory status in an attempt to restore the nervous system homeostasis, since excessive inflammatory response can cause irreversible damage to tissue preservation.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"11786469211069946"},"PeriodicalIF":4.4,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/ee/55/10.1177_11786469211069946.PMC8808026.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39893738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential Effect of Non-Purified and Semi-Purified Standard Diets on Kynurenine and Peripheral Metabolites in Male C57BL/6J Mice.","authors":"Yuhei Yajima,&nbsp;Alato Okuno,&nbsp;Isamu Nakamura,&nbsp;Teruo Miyazaki,&nbsp;Akira Honda,&nbsp;Atsushi Toyoda","doi":"10.1177/11786469211066285","DOIUrl":"https://doi.org/10.1177/11786469211066285","url":null,"abstract":"<p><p>The kynurenine (Kyn) pathway plays crucial roles in several inflammation-induced disorders such as depression. In this study, we measured Kyn and other related molecules in the blood plasma, brain, and urine of male C57BL/6J mice (B6) fed non-purified (MF) and semi-purified (AIN-93G and AIN-93M) standard rodent diets. Mice fed MF had increased plasma Kyn levels compared with those on AIN93-based diets, as well as decreased hippocampal Kyn levels compared with those fed AIN-93G. Previous studies showed that branched chain amino acids (BCAAs) suppress peripheral blood Kyn transportation to the brain, but plasma BCAA levels were not significantly different between the diet groups in our study. Urine metabolome analysis revealed that feed ingredients affected the excretion of many metabolites, and MF-fed mice had elevated excretion of kynurenic and quinolinic acids, pivotal metabolites in the Kyn pathway. Collectively, the level of critical metabolites in the Kyn pathway in the central and peripheral tissues was strongly affected by feed ingredients. Therefore, feed selection is a critical factor to ensure the reproducibility of experimental data in studies involving rodent models.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"11786469211066285"},"PeriodicalIF":4.4,"publicationDate":"2022-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/b0/7a/10.1177_11786469211066285.PMC8733355.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39912756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Indoleamine 2,3-Dioxygenase-1 Expression is Changed During Bladder Cancer Cell Invasion.","authors":"Hellen Joyce Sousa Pereira Santos,&nbsp;Luiz Henrique Gomes Matheus,&nbsp;Aline Silva,&nbsp;Stephanie Vanin Dalmazzo,&nbsp;Andressa Assunção Santos,&nbsp;Letícia Rafaela Alves Rubens Santos,&nbsp;Diego Mota Souza,&nbsp;Sabrina Thalita Reis,&nbsp;Ivan Pereira Nascimento,&nbsp;Humberto Dellê","doi":"10.1177/11786469211065612","DOIUrl":"https://doi.org/10.1177/11786469211065612","url":null,"abstract":"<p><p>The severity of the bladder carcinoma (BC) is directly linked to cell invasion and metastasis. Indoleamine 2,3-dioxygenase-1 (IDO-1) is an INF-γ-induced immunomodulating enzyme that has been linked to the cancer cell invasiveness. Because IDO1 is variable among the tumors, we analyzed its expression in the BC invasion using BC mice models and cell culture. MB49 cells were orthotopically or ectopically inoculated in C57Bl6 mice to evaluate IDO1 by immunohistochemistry. For in vitro experiments, expression of IDO1 and INF-γ was evaluated in grade-1 (RT4) and in grade-3 (T24) BC cell lines. Invading and non-invading T24 cells were separated using the Matrigel/Transwell system, of which total RNA was extracted immediately or after 2 weeks of subculture. Finally, IDO1 was silenced in T24 cells to verify its role on cell invasiveness. In both animal models, IDO1 was differentially expressed between non-invading and invading cells. In cell culture, T24 cells expressed more IDO1 than RT4 cells, independently of the INF-γ expression. IDO1 was differentially expressed between non-invading and invading T24 cells, a difference that was lost by long-time subculture. IDO1 silencing resulted in diminished cell invasiveness. In conclusion, IDO1 expression is changed during bladder carcinoma invasion, playing an important role in this process.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"11786469211065612"},"PeriodicalIF":4.4,"publicationDate":"2022-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/d0/5c/10.1177_11786469211065612.PMC8733347.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39912755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Induction of tryptophan 2,3-dioxygenase expression in human monocytic leukemia/lymphoma cell lines THP-1 and U937.","authors":"Delia Hoffmann,&nbsp;Luc Pilotte,&nbsp;Vincent Stroobant,&nbsp;Benoit J Van den Eynde","doi":"10.1177/1178646919891736","DOIUrl":"https://doi.org/10.1177/1178646919891736","url":null,"abstract":"<p><p>Tumor-associated macrophages are immune cells with diverse functions in tumor development. Among other functions, they downregulate immune-mediated tumor rejection by depriving lymphocytes of nutrients. The essential amino acid tryptophan is metabolized by the enzymes indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase (TDO). Indoleamine 2,3-dioxygenase 1 is expressed in a large number of human tumors, and inhibitors are in development to improve immunotherapy. Tryptophan 2,3-dioxygenase was also found in human tumors and preclinical working models confirmed its immunosuppressive power. We explored a potential expression of TDO by macrophages. This enzyme could be induced in two human cell lines, THP-1 and U937, by incubation with phorbol myristate acetate, lipopolysaccharide, and interferon gamma. Phorbol-myristate-acetate-mediated induction was inhibited by rottlerin, a protein kinase C inhibitor. In contrast to these monocytic cell lines, other cell lines or fresh human monocytes isolated from peripheral blood mononuclear cells and differentiated into proinflammatory or anti-inflammatory macrophages could not be induced to express TDO. Our results suggest that TDO might play an immunosuppressive role in human monocytic leukemias but not in untransformed macrophages.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919891736"},"PeriodicalIF":4.4,"publicationDate":"2019-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919891736","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37512932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lipopolysaccharide Increases Cortical Kynurenic Acid and Deficits in Reference Memory in Mice.","authors":"Lee Peyton,&nbsp;Alfredo Oliveros,&nbsp;Maximilian Tufvesson-Alm,&nbsp;Lilly Schwieler,&nbsp;Phillip Starski,&nbsp;Göran Engberg,&nbsp;Sopie Erhardt,&nbsp;Doo-Sup Choi","doi":"10.1177/1178646919891169","DOIUrl":"https://doi.org/10.1177/1178646919891169","url":null,"abstract":"<p><p>Kynurenic acid (KYNA), a glial-derived metabolite of tryptophan metabolism, is an antagonist of the alpha 7 nicotinic acetylcholine receptor and the glycine-binding site of <i>N</i>-methyl-d-aspartate (NMDA) receptors. Kynurenic acid levels are increased in both the brain and cerebrospinal fluid of several psychiatric disorders including bipolar disorder, schizophrenia, and Alzheimer disease. In addition, pro-inflammatory cytokines have been found to be elevated in the blood of schizophrenic patients suggesting inflammation may play a role in psychiatric illness. As both pro-inflammatory cytokines and KYNA can be elevated in the brain by peripheral lipopolysaccharide (LPS) injection, we therefore sought to characterize the role of neuroinflammation on learning and memory using a well-described dual-LPS injection model. Mice were injected with an initial injection (0.25 mg/kg LPS, 0.50 mg/kg, or saline) of LPS and then administrated a second injection 16 hours later. Our results indicate both 0.25 and 0.50 mg/kg dual-LPS treatment increased l-kynurenine and KYNA levels in the medial pre-frontal cortex (mPFC). Mice exhibited impaired acquisition of CS+ (conditioned stimulus) Pavlovian conditioning. Notably, mice showed impairment in reference memory while working memory was normal in an 8-arm maze. Taken together, our findings suggest that neuroinflammation induced by peripheral LPS administration contributes to cognitive dysfunction.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919891169"},"PeriodicalIF":4.4,"publicationDate":"2019-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919891169","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37508045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of Dipicolinic Acid in \"Natto\" by High-Performance Liquid Chromatography Coupled With Postcolumn Photoirradiation With Zinc Acetate.","authors":"Ken-Ichi Mawatari,&nbsp;Motomasa Atsumi,&nbsp;Fumiya Nakamura,&nbsp;Makoto Yasuda,&nbsp;Tomoko Fukuuchi,&nbsp;Noriko Yamaoka,&nbsp;Kiyoko Kaneko,&nbsp;Kazuya Nakagomi,&nbsp;Naoto Oku","doi":"10.1177/1178646919852120","DOIUrl":"https://doi.org/10.1177/1178646919852120","url":null,"abstract":"<p><p>A system was developed for determining dipicolinic acid in \"natto\" using liquid chromatography with fluorometric detection. The compound was separated by reversed-phase chromatography using a mobile phase of 0.1 mol/L disodium hydrogen phosphate, 0.05 mol/L citric acid buffer (adjusted to pH 3.0) containing 3.0 mmol/L zinc acetate and 35 mmol/L perchloric acid. The compound in the column effluent was irradiated with ultraviolet light to produce fluorescence. This fluorescence was monitored at an excitation at 336 nm and an emission at 448 nm. The calibration curve for dipicolinic acid was observed to be linear in a range of 0.2 to 112 ng. The dipicolinic acid content of natto was 7.24 ± 0.54 mg/100 g (wet weight, mean ± standard deviation [SD], n = 6).</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919852120"},"PeriodicalIF":4.4,"publicationDate":"2019-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919852120","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37377797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microorganisms, Tryptophan Metabolism, and Kynurenine Pathway: A Complex Interconnected Loop Influencing Human Health Status.","authors":"Mona Dehhaghi,&nbsp;Hamed Kazemi Shariat Panahi,&nbsp;Gilles J Guillemin","doi":"10.1177/1178646919852996","DOIUrl":"https://doi.org/10.1177/1178646919852996","url":null,"abstract":"<p><p>The kynurenine pathway is important in cellular energy generation and limiting cellular ageing as it degrades about 90% of dietary tryptophan into the essential co-factor NAD⁺ (nicotinamide adenine dinucleotide). Prior to the production of NAD⁺, various intermediate compounds with neuroactivity (kynurenic acid, quinolinic acid) or antioxidant activity (3-hydroxykynurenine, picolinic acid) are synthesized. The kynurenine metabolites can participate in numerous neurodegenerative disorders (Alzheimer disease, amyotrophic lateral sclerosis, Huntington disease, and Parkinson disease) or other diseases such as AIDS, cancer, cardiovascular diseases, inflammation, and irritable bowel syndrome. Recently, the role of gut in affecting the emotional and cognitive centres of the brain has attracted a great deal of attention. In this review, we focus on the bidirectional communication between the gut and the brain, known as the gut-brain axis. The interaction of components of this axis, namely, the gut, its microbiota, and gut pathogens; tryptophan; the kynurenine pathway on tryptophan availability; the regulation of kynurenine metabolite concentration; and diversity and population of gut microbiota, has been considered.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919852996"},"PeriodicalIF":4.4,"publicationDate":"2019-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919852996","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37377798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glioblastoma: Role of Mitochondria N-acetylserotonin/Melatonin Ratio in Mediating Effects of miR-451 and Aryl Hydrocarbon Receptor and in Coordinating Wider Biochemical Changes.","authors":"George Anderson,&nbsp;Russell J Reiter","doi":"10.1177/1178646919855942","DOIUrl":"https://doi.org/10.1177/1178646919855942","url":null,"abstract":"<p><p>A wide array of different factors and processes have been linked to the biochemical underpinnings of glioblastoma multiforme (GBM) and glioblastoma stem cells (GSC), with no clear framework in which these may be integrated. Consequently, treatment of GBM/GSC is generally regarded as very poor. This article provides a framework that is based on alterations in the regulation of the melatonergic pathways within mitochondria of GBM/GSC. It is proposed that the presence of high levels of mitochondria-synthesized melatonin is toxic to GBM/GSC, with a number of processes in GBM/GSC acting to limit melatonin's synthesis in mitochondria. One such factor is the aryl hydrocarbon receptor, which increases cytochrome P450 (CYP)1b1 in mitochondria, leading to the 'backward' conversion of melatonin to <i>N</i>-acetylserotonin (NAS). <i>N</i>-acetylserotonin has some similar, but some important differential effects compared with melatonin, including its activation of the tyrosine receptor kinase B (TrkB) receptor. TrkB activation is important to GBM/GSC survival and proliferation. A plethora of significant, but previously disparate, data on GBM/GSC can then be integrated within this framework, including miR-451, AMP-activated protein kinase (AMPK)/mTOR, 14-3-3 proteins, sirtuins, tryptophan 2,3-dioxygenase, and the kynurenine pathways. Such a conceptualization provides a framework for the development of more effective treatment for this poorly managed condition.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919855942"},"PeriodicalIF":4.4,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919855942","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37106350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diet-Related Metabolic Perturbations of Gut Microbial Shikimate Pathway-Tryptamine-tRNA Aminoacylation-Protein Synthesis in Human Health and Disease.","authors":"Elena L Paley","doi":"10.1177/1178646919834550","DOIUrl":"https://doi.org/10.1177/1178646919834550","url":null,"abstract":"<p><p>Human gut bacterial Na(+)-transporting NADH:ubiquinone reductase (NQR) sequence is associated with Alzheimer disease (AD). Here, Alzheimer disease-associated sequence (ADAS) is further characterized in cultured spore-forming <i>Clostridium sp</i>. Tryptophan and NQR substrate ubiquinone have common precursor chorismate in microbial shikimate pathway. Tryptophan-derived tryptamine presents in human diet and gut microbiome. Tryptamine inhibits tryptophanyl-tRNA synthetase (TrpRS) with consequent neurodegeneration in cell and animal models. Tryptophanyl-tRNA synthetase inhibition causes protein biosynthesis impairment similar to that revealed in AD. Tryptamine-induced TrpRS gene-dose reduction is associated with TrpRS protein deficiency and cell death. In animals, tryptamine treatment results in toxicity, weight gain, and prediabetes-related hypoglycemia. Sequence analysis of gut microbiome database reveals 89% to 100% ADAS nucleotide identity in American Indian (Cheyenne and Arapaho [C&A]) Oklahomans, of which ~93% being overweight or obese and 50% self-reporting type 2 diabetes (T2D). Alzheimer disease-associated sequence occurs in 10.8% of C&A vs 1.3% of healthy American population. This observation is of considerable interest because T2D links to AD and obesity. Alzheimer disease-associated sequence prevails in gut microbiome of colorectal cancer, which linked to AD. Metabolomics revealed that tryptamine, chorismate precursor quinate, and chorismate product 4-hydroxybenzoate (ubiquinone precursor) are significantly higher, while tryptophan-containing dipeptides are lower due to tRNA aminoacylation deficiency in C&A compared with non-native Oklahoman who showed no ADAS. Thus, gut microbial tryptamine overproduction correlates with ADAS occurrence. Antibiotic and diet additives induce ADAS and tryptamine. Mitogenic/cytotoxic tryptamine cause microbial and human cell death, gut dysbiosis, and consequent disruption of host-microbe homeostasis. Present analysis of 1246 participants from 17 human gut metagenomics studies revealed ADAS in cell death diseases.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919834550"},"PeriodicalIF":4.4,"publicationDate":"2019-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919834550","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37280671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simultaneous Determination of Kynurenine and Kynurenic Acid by High-Performance Liquid Chromatography Photoirradiation System Using a Mobile Phase Containing 18-crown-6.","authors":"Motomasa Atsumi,&nbsp;Ken-Ichi Mawatari,&nbsp;Akari Morooka,&nbsp;Makoto Yasuda,&nbsp;Tomoko Fukuuchi,&nbsp;Noriko Yamaoka,&nbsp;Kiyoko Kaneko,&nbsp;Kazuya Nakagomi,&nbsp;Naoto Oku","doi":"10.1177/1178646919834551","DOIUrl":"https://doi.org/10.1177/1178646919834551","url":null,"abstract":"<p><p>A high-performance liquid chromatography (HPLC) system has been developed for the fluorometric determination of kynurenine (KYN) and kynurenic acid (KYNA) in human serum using a mobile phase containing 18-crown-6. A retention time of KYNA was adjusted with pH of phosphate buffer in 18-crown-6. KYN and KYNA were separated on a CAPCELLPAK C18 (250 × 4.6 mm i.d.). The mobile phase consisted of 35 mmol/L phosphate buffer (pH 8.0)/methanol (85/15, v/v) containing 35 mmol/L hydrogen peroxide and 10 mmol/L 18-crown-6. The retention times of KYN and KYNA were 18and 24 minutes, respectively. The calibration graphs of KYN and KYNA were linear over the range 180 to 2900 and 1 to 84 nmol/L by injecting a 50-μL volume of KYN and KYNA, respectively. Pretreatment of serum was achieved by deproteinization only. The mean recoveries of KYN and KYNA from serum were more than 97%.</p>","PeriodicalId":520654,"journal":{"name":"International journal of tryptophan research : IJTR","volume":" ","pages":"1178646919834551"},"PeriodicalIF":4.4,"publicationDate":"2019-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1178646919834551","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37241655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}