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Fukushima T, Kansaku A, Umino M, Sakamoto T, Onozato M. Evaluation of D-amino acid oxidase activity in rat kidney using a D-kynurenine derivative, 6-methylthio-D-kynurenine: An in vivo microdialysis study. Drug Discov Ther 2024; 17:434-439. [PMID: 38044118 DOI: 10.5582/ddt.2023.01083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
D-Amino acid oxidase (DAO), a D-amino acid metabolizing enzyme, is reportedly associated with the psychiatric disease schizophrenia, suggesting a role for DAO inhibitors in its treatment. We have previously reported that DAO catalyzes the conversion of nonfluorescent 6-methylthio-D-kynurenine (MeS-D-KYN) to fluorescent 5-methylthiokynurenic acid (MeS-KYNA) in vitro. The present study aimed to determine the potential of MeS-D-KYN in evaluating DAO activity in vivo using renal microdialysis technique in rats. Male Sprague-Dawley rats were subjected to linear microdialysis probe implantation in the left kidney. Continuous perfusion of MeS-D-KYN was maintained, and DAO activity in the kidney cortex was evaluated by measuring the MeS-KYNA content in the microdialysate. The microdialysate was collected every 30 min and analyzed by high-performance liquid chromatography with fluorescence detection, monitored at 450 nm with an excitation wavelength of 364 nm. A significant production of MeS-KYNA was observed during, but not before, infusion of MeS-D-KYN, indicating that this compound is not endogenous. MeS-KYNA production was suppressed by the co-infusion of DAO inhibitor, 5-chlorobenzo[d]isoxazol-3-ol (CBIO), suggesting that MeS-D-KYN was converted to MeS-KYNA by renal DAO. Moreover, oral administration of CBIO effectively suppressed DAO activity in a dose-dependent manner. DAO converted MeS-D-KYN to MeS-KYNA in vivo, suggesting the potential of this compound in evaluating DAO activity. The use of the renal microdialysis technique developed in this study facilitates the monitoring of DAO activity in live experimental animals.
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Affiliation(s)
- Takeshi Fukushima
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Ayano Kansaku
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Maho Umino
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Tatsuya Sakamoto
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Mayu Onozato
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
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Sakamoto T, Onozato M, Sugasawa H, Fukushima T. Substituted kynurenic acid derivatives as fluorophore-based probes for D- and L-amino acid oxidase assays and their in vitro application in eels. Analyst 2023; 148:5991-6000. [PMID: 37876282 DOI: 10.1039/d3an01325a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
High levels of D-amino acid oxidase (DAO) are associated with neurological and psychiatric disorders, while L-amino acid oxidase (LAO) exhibits antimicrobial and antitumor properties. The enzymatic conversion of the non-fluorescent kynurenine (KYN) into the endogenous weak fluorescent kynurenic acid (KYNA) by the action of DAO has previously been reported. However, the fluorescence of KYNA can be improved by changing the substituents on the aromatic rings. In this study, we prepared different 6-phenyl-substituted KYNA derivatives and investigated their fluorescence properties. Among them, 2-MePh-KYNA showed the maximum fluorescence quantum yield of 0.881 at 340 nm excitation and 418 nm emission wavelengths. The effects of solvent properties (dielectric constant, pKa, viscosity, and proticity) on the fluorescence intensity (FLI) of the KYNA derivatives were explored. The FLI of 2-MePh-KYNA was significantly large in protic solvents. Subsequently, 2-MePh-D-KYN and 2-MePh-L-KYN were prepared with high enantiopurity (>99.25%) for the enzymatic conversion. 2-MePh-D-KYN exhibited high sensitivity (∼19 times that of a commercial DAO substrate and ∼60 times that of the previously reported MeS-D-KYN) and high selectivity, as it was not cross-reactive towards LAO, while 2-MePh-L-KYN was also converted into 2-MePh-KYNA by LAO. Furthermore, the 2-MePh-D-KYN probe successfully detected DAO in eel liver, kidney, and heparin-anticoagulated plasma in the in vitro study.
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Affiliation(s)
- Tatsuya Sakamoto
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
| | - Mayu Onozato
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
| | - Hiroshi Sugasawa
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
| | - Takeshi Fukushima
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
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Lo YC, Lin CL, Fang WY, Lőrinczi B, Szatmári I, Chang WH, Fülöp F, Wu SN. Effective Activation by Kynurenic Acid and Its Aminoalkylated Derivatives on M-Type K + Current. Int J Mol Sci 2021; 22:ijms22031300. [PMID: 33525680 PMCID: PMC7865226 DOI: 10.3390/ijms22031300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/24/2022] Open
Abstract
Kynurenic acid (KYNA, 4-oxoquinoline-2-carboxylic acid), an intermediate of the tryptophan metabolism, has been recognized to exert different neuroactive actions; however, the need of how it or its aminoalkylated amide derivative N-(2-(dimethylamino)ethyl)-3-(morpholinomethyl)-4-oxo-1,4-dihydroquinoline-2-carboxamide (KYNA-A4) exerts any effects on ion currents in excitable cells remains largely unmet. In this study, the investigations of how KYNA and other structurally similar KYNA derivatives have any adjustments on different ionic currents in pituitary GH3 cells and hippocampal mHippoE-14 neurons were performed by patch-clamp technique. KYNA or KYNA-A4 increased the amplitude of M-type K+ current (IK(M)) and concomitantly enhanced the activation time course of the current. The EC50 value required for KYNA- or KYNA-A4 -stimulated IK(M) was yielded to be 18.1 or 6.4 μM, respectively. The presence of KYNA or KYNA-A4 shifted the relationship of normalized IK(M)-conductance versus membrane potential to more depolarized potential with no change in the gating charge of the current. The voltage-dependent hysteretic area of IK(M) elicited by long-lasting triangular ramp pulse was observed in GH3 cells and that was increased during exposure to KYNA or KYNA-A4. In cell-attached current recordings, addition of KYNA raised the open probability of M-type K+ channels, along with increased mean open time of the channel. Cell exposure to KYNA or KYNA-A4 mildly inhibited delayed-rectifying K+ current; however, neither erg-mediated K+ current, hyperpolarization-activated cation current, nor voltage-gated Na+ current in GH3 cells was changed by KYNA or KYNA-A4. Under whole-cell, current-clamp recordings, exposure to KYNA or KYNA-A4 diminished the frequency of spontaneous action potentials; moreover, their reduction in firing frequency was attenuated by linopirdine, yet not by iberiotoxin or apamin. In hippocampal mHippoE-14 neurons, the addition of KYNA also increased the IK(M) amplitude effectively. Taken together, the actions presented herein would be one of the noticeable mechanisms through which they modulate functional activities of excitable cells occurring in vivo.
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Affiliation(s)
- Yi-Ching Lo
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Correspondence: (Y.-C.L.); (S.-N.W.); Tel.: +886-7-3234686 (Y.-C.L.); +886-6-2353535-5334 (S.-N.W.); Fax: +886-7-3234686 (Y.-C.L.); +886-6-2362780 (S.-N.W.)
| | - Chih-Lung Lin
- Department of Neurosurgery, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan;
- Department of Neurosurgery, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Wei-Yu Fang
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
| | - Bálint Lőrinczi
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
| | - István Szatmári
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
| | - Wan-Hsuan Chang
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Ferenc Fülöp
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
- MTA-SZTE Stereochemistry Research Group, Hungarian Academy of Sciences, Eötvös u. 6, H-6720 Szeged, Hungary
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Correspondence: (Y.-C.L.); (S.-N.W.); Tel.: +886-7-3234686 (Y.-C.L.); +886-6-2353535-5334 (S.-N.W.); Fax: +886-7-3234686 (Y.-C.L.); +886-6-2362780 (S.-N.W.)
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Szűcs E, Stefanucci A, Dimmito MP, Zádor F, Pieretti S, Zengin G, Vécsei L, Benyhe S, Nalli M, Mollica A. Discovery of Kynurenines Containing Oligopeptides as Potent Opioid Receptor Agonists. Biomolecules 2020; 10:biom10020284. [PMID: 32059524 PMCID: PMC7072329 DOI: 10.3390/biom10020284] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/03/2020] [Accepted: 02/06/2020] [Indexed: 12/17/2022] Open
Abstract
Kynurenine (kyn) and kynurenic acid (kyna) are well-defined metabolites of tryptophan catabolism collectively known as "kynurenines", which exert regulatory functions in host-microbiome signaling, immune cell response, and neuronal excitability. Kynurenine containing peptides endowed with opioid receptor activity have been isolated from natural organisms; thus, in this work, novel opioid peptide analogs incorporating L-kynurenine (L-kyn) and kynurenic acid (kyna) in place of native amino acids have been designed and synthesized with the aim to investigate the biological effect of these modifications. The kyna-containing peptide (KA1) binds selectively the m-opioid receptor with a Ki = 1.08 ± 0.26 (selectivity ratio m/d/k = 1:514:10000), while the L-kyn-containing peptide (K6) shows a mixed binding affinity for m, d, and k-opioid receptors, with efficacy and potency (Emax = 209.7 + 3.4%; LogEC50 = -5.984 + 0.054) higher than those of the reference compound DAMGO. This novel oligopeptide exhibits a strong antinociceptive effect after i.c.v. and s.c. administrations in in vivo tests, according to good stability in human plasma (t1/2 = 47 min).
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Affiliation(s)
- Edina Szűcs
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62., H-6726 Szeged, Hungary; (E.S.); (F.Z.); (S.B.)
- Doctoral School of Theoretical Medicine, Faculty of Medicine, University of Szeged, Dómtér 10, H-6720 Szeged, Hungary
| | - Azzurra Stefanucci
- Department of Pharmacy, University of Chieti-Pescara “G. d’Annunzio”, Via dei Vestini 31, 66100 Chieti, Italy; (M.P.D.); (A.M.)
- Correspondence:
| | - Marilisa Pia Dimmito
- Department of Pharmacy, University of Chieti-Pescara “G. d’Annunzio”, Via dei Vestini 31, 66100 Chieti, Italy; (M.P.D.); (A.M.)
| | - Ferenc Zádor
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62., H-6726 Szeged, Hungary; (E.S.); (F.Z.); (S.B.)
| | - Stefano Pieretti
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy;
| | - Gokhan Zengin
- Department of Biology, Science Faculty, Selcuk University, 42250 Konya, Turkey;
| | - László Vécsei
- MTA-SZTE Neuroscience Research Group, Department of Neurology, Interdisciplinary Excellence Centre, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary;
| | - Sándor Benyhe
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62., H-6726 Szeged, Hungary; (E.S.); (F.Z.); (S.B.)
| | - Marianna Nalli
- Laboratory affiliated with the Institute Pasteur Italy-Cenci Bolognetti Foundation, Department of Drug Chemistry and Technologies, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy;
| | - Adriano Mollica
- Department of Pharmacy, University of Chieti-Pescara “G. d’Annunzio”, Via dei Vestini 31, 66100 Chieti, Italy; (M.P.D.); (A.M.)
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5
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Chen Y, Chen H, Shi G, Yang M, Zheng F, Zheng Z, Zhang S, Zhong S. Ultra-performance liquid chromatography-tandem mass spectrometry quantitative profiling of tryptophan metabolites in human plasma and its application to clinical study. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1128:121745. [PMID: 31586884 DOI: 10.1016/j.jchromb.2019.121745] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 07/11/2019] [Accepted: 08/02/2019] [Indexed: 02/05/2023]
Abstract
A sensitive, rapid and reliable ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to assay tryptophan (TRP) and its nine metabolites, including kynurenine (KYN), kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK), 3-hydroxyanthranilic acid (3-HAA), xanthurenic acid (XA), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), 3-indolepropionic acid (IPA) and 3-indoleacetic acid (IAA) in human plasma. Tryptophan-d5 (TRP-d5) and carbamazepine (CAR) were applied to the method quantification, where TRP-d5 was the corresponding internal standard (IS) for TRP and KYN, and CAR was the corresponding IS for the other analytes. Plasma samples were processed by deproteinisation with acetonitrile, followed by separation on an Acquity UPLC HSS T3 column by using gradient elution with 0.1% (v/v) formic acid in water and acetonitrile and detection by electrospray ionisation tandem mass spectrometry in positive ion multiple reaction monitoring (MRM) within a total run time of 5 min. The calibration ranges were 3-600 ng/mL for 3-HK, 1.5-300 ng/mL for 5-HT, 25-5000 ng/mL for KYN, 1-200 ng/mL for XA, 100-20,000 ng/mL for TRP, 5-1000 ng/mL for KYNA, 2-400 ng/mL for 3-HAA, 2.5-500 ng/mL for 5-HIAA and 10-2000 ng/mL for IAA and IPA. All intra- and inter-day analytical variations were acceptable. Matrix effect and recovery evaluation proved that matrix effect can be negligible, and sample preparation approach was effective. The newly developed method can simultaneously determine a panel of TRP metabolites and was successfully applied in the clinical study characterising TRP metabolism in healthy volunteers.
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Affiliation(s)
- Yun Chen
- Clinical Pharmacy Research Center, Shantou University Medical College, Shantou 515031, PR China; Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, PR China
| | - Hui Chen
- Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, PR China
| | - Ganggang Shi
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, PR China
| | - Min Yang
- Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, PR China
| | - Fuchun Zheng
- Pharmaceutical Laboratory, The First Affiliated Hospital, Shantou University Medical College, Shantou 515041, PR China
| | - Zhijie Zheng
- Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, PR China
| | - Shuyao Zhang
- Clinical Pharmacy Research Center, Shantou University Medical College, Shantou 515031, PR China; Department of Pharmacy, Cancer Hospital of Shantou University Medical College, Shantou 515031, PR China; Department of Pharmacy, Guangzhou Red Cross Hospital Affiliated of Jinan University Medical College, Guangzhou 510220, PR China.
| | - Shilong Zhong
- Clinical Pharmacy Research Center, Shantou University Medical College, Shantou 515031, PR China; Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, PR China.
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Fehér E, Szatmári I, Dudás T, Zalatnai A, Farkas T, Lőrinczi B, Fülöp F, Vécsei L, Toldi J. Structural Evaluation and Electrophysiological Effects of Some Kynurenic Acid Analogs. Molecules 2019; 24:molecules24193502. [PMID: 31561643 PMCID: PMC6803921 DOI: 10.3390/molecules24193502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 09/23/2019] [Accepted: 09/24/2019] [Indexed: 01/28/2023] Open
Abstract
Kynurenic acid (KYNA), a metabolite of tryptophan, as an excitatory amino acid receptor antagonist is an effective neuroprotective agent in case of excitotoxicity, which is the hallmark of brain ischemia and several neurodegenerative processes. Therefore, kynurenine pathway, KYNA itself, and its derivatives came into the focus of research. During the past fifteen years, our research group has developed several neuroactive KYNA derivatives, some of which proved to be neuroprotective in preclinical studies. In this study, the synthesis of these KYNA derivatives and their evaluation with divergent molecular characteristics are presented together with their most typical effects on the monosynaptic transmission in CA1 region of the hippocampus of the rat. Their effects on the basic neuronal activity (on the field excitatory postsynaptic potentials: fEPSP) were studied in in vitro hippocampal slices in 1 and 200 μM concentrations. KYNA and its derivative 4 in both 1 and 200 μM concentrations proved to be inhibitory, while derivative 8 only in 200 μM decreased the amplitudes of fEPSPs. Derivative 5 facilitated the fEPSPs in 200 μM concentration. This is the first comparative study which evaluates the structural and functional differences of formerly and newly developed KYNA analogs. Considerations on possible relations between molecular structures and their physiological effects are presented.
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Affiliation(s)
- Evelin Fehér
- Department of Neurology, Interdisciplinary Excellence Centre, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Semmelweis u. 6, H-6725 Szeged, Hungary.
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
| | - István Szatmári
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
- Stereochemistry Research Group of the Hungarian Academy of Sciences, Eötvös utca 6, H-6720 Szeged, Hungary.
- Institute of Pharmaceutical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
| | - Tamás Dudás
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
| | - Anna Zalatnai
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
| | - Tamás Farkas
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
| | - Bálint Lőrinczi
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
- Stereochemistry Research Group of the Hungarian Academy of Sciences, Eötvös utca 6, H-6720 Szeged, Hungary.
| | - Ferenc Fülöp
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
- Stereochemistry Research Group of the Hungarian Academy of Sciences, Eötvös utca 6, H-6720 Szeged, Hungary.
- Institute of Pharmaceutical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
| | - László Vécsei
- Department of Neurology, Interdisciplinary Excellence Centre, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, Semmelweis u. 6, H-6725 Szeged, Hungary.
- MTA-SZTE Neuroscience Research Group, Semmelweis u. 6, H-6725 Szeged, Hungary.
| | - József Toldi
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
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Jayawickrama GS, Nematollahi A, Sun G, Church WB. Improvement of kynurenine aminotransferase-II inhibitors guided by mimicking sulfate esters. PLoS One 2018; 13:e0196404. [PMID: 29689093 PMCID: PMC5915280 DOI: 10.1371/journal.pone.0196404] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/12/2018] [Indexed: 01/08/2023] Open
Abstract
The mammalian kynurenine aminotransferase (KAT) enzymes are a family of related isoforms that are pyridoxal 5’-phosphate-dependent, responsible for the irreversible transamination of kynurenine to kynurenic acid. Kynurenic acid is implicated in human diseases such as schizophrenia where it is found in elevated levels and consequently KAT-II, as the isoform predominantly responsible for kynurenic acid production in the brain, has been targeted for the development of specific inhibitors. One class of compounds that have also shown inhibitory activity towards the KAT enzymes are estrogens and their sulfate esters. Estradiol disulfate in particular is very strongly inhibitory and it appears that the 17-sulfate makes a significant contribution to its potency. The work here demonstrates that the effect of this moiety can be mirrored in existing KAT-II inhibitors, from the development of two novel inhibitors, JN-01 and JN-02. Both inhibitors were based on NS-1502 (IC50: 315 μM), but the deliberate placement of a sulfonamide group significantly improved the potency of JN-01 (IC50: 73.8 μM) and JN-02 (IC50: 112.8 μM) in comparison to the parent compound. This 3–4 fold increase in potency shows the potential of these moieties to be accommodated in the KAT-II active site and the effect they can have on improving inhibitors, and the environments in the KAT-II have been suitably modelled using docking calculations.
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Affiliation(s)
- Gayan S. Jayawickrama
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
| | - Alireza Nematollahi
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
| | - Guanchen Sun
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
| | - William Bret Church
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
- * E-mail:
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Sormacheva ED, Sherin PS, Tsentalovich YP. Dimerization and oxidation of tryptophan in UV-A photolysis sensitized by kynurenic acid. Free Radic Biol Med 2017; 113:372-384. [PMID: 29024806 DOI: 10.1016/j.freeradbiomed.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 11/24/2022]
Abstract
Photoinduced generation of radicals in the eye lens may play an important role in the modification of proteins leading to their coloration, aggregation, and insolubilization. The radicals can be formed via the reactions of photoexcited endogenous chromophores of the human lens with lens proteins, in particular with tryptophan residues. In the present work we studied the reactions induced by UV-A (315-400nm) light between kynurenic acid (KNA), an effective photosensitizer present in the human lens, and N-acetyl-L-tryptophan (NTrpH) under aerobic and anaerobic conditions. Our results show that the reaction mechanism strongly depends on the presence of oxygen in solution. Under aerobic conditions, the generation of singlet oxygen is the major channel of the effective NTrpH oxidation. In argon-bubbled solutions, the quenching of triplet KNA by NTrpH results in the formation of KNA•- and NTrp• radicals. Under laser pulse irradiation, when the radical concentration is high, the main pathway of the radical decay is the back electron transfer with the restoration of initial reagents. Other reactions include (i) the radical combination yielding NTrp dimers and (ii) the oxygen atom transfer from KNA•- to NTrp• with the formation of oxidized NTrp species and deoxygenated KNA products. In continuous-wave photolysis, even trace amounts of molecular oxygen are sufficient to oxidize the majority of KNA•- radicals with the rate constant of (2.0 ± 0.2) × 109M-1s-1, leading to the restoration of KNA and the formation of superoxide radical O2•-. The latter reacts with NTrp• via either the radical combination to form oxidized NTrp (minor pathway), or the electron transfer to restore NTrpH in the ground state (major pathway). As the result, the quantum yields of the starting compound decomposition under continuous-wave anaerobic photolysis are rather low: 1.6% for NTrpH and 0.02% for KNA. The photolysis of KNA with alpha-crystallin yields the same deoxygenated KNA products as the photolysis of KNA with NTrpH, indicating the similarity of the photolysis mechanisms. Thus, inside the eye lens KNA can sensitize both protein photooxidation and protein covalent cross-linking with the minor self-degradation. This may play an important role in the lens protein modifications during the normal aging and cataract development.
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Affiliation(s)
- Ekaterina D Sormacheva
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia.
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia
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9
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Samanta A, Guchhait N, Bhattacharya SC. Photophysical aspects of biological photosensitizer Kynurenic acid from the perspective of experimental and quantum chemical study. Spectrochim Acta A Mol Biomol Spectrosc 2014; 129:457-465. [PMID: 24751782 DOI: 10.1016/j.saa.2014.03.079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/11/2014] [Accepted: 03/21/2014] [Indexed: 06/03/2023]
Abstract
In the present contribution, we have explored ground and excited state spectroscopic properties of an antiexcitotoxic and anticonvulsant drug, Kynurenic acid (KA), through steady-state absorption, emission and time-resolved emission spectroscopy and quantum chemical calculations. The main focus of this article is to illustrate the effects of various parameters such as the nature of the solvents and pH of the medium on the spectral properties of KA which confirms the presence of different neutral and ionic species in the ground and excited states. The molecule KA exists mainly as keto- or anionic form in the ground state, whereas the main contribution of its emission is arising from the keto tautomer in the excited state. Quantum chemical calculations by Density Functional Theory (DFT) method has been effectively employed to correlate the experimental findings. The ground and excited state properties of KA ascertained by means of experimental and theoretical method reveal that it resembles well with other two compounds, 4-hydroxyquinoline and xanthurenic acid formed by the decomposition of UV filters.
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Affiliation(s)
- Anuva Samanta
- Department of Chemistry, Jadavpur University Raja S.C. Mallick Road, Kolkata 700 032, India
| | - Nikhil Guchhait
- Department of Chemistry, University of Calcutta 92, A.P.C. Road, Kolkata 700 009, India.
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10
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Zgrajka W, Turska M, Rajtar G, Majdan M, Parada-Turska J. Kynurenic acid content in anti-rheumatic herbs. Ann Agric Environ Med 2013; 20:800-802. [PMID: 24364456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
INTRODUCTION The use of herbal medicines is common among people living in rural areas and increasingly popular in urbanized countries. Kynurenic acid (KYNA) is a metabolite of kynurenine possessing anti-inflammatory, anti-oxidative and pain reliving properties. Previous data indicated that the content of KYNA in the synovial fluid of patients with rheumatoid arthritis is lower than in patients with osteoarthritis. Rheumatoid arthritis is a chronic, systemic inflammatory disorder affecting about 1% of the world's population. AIM The aim of the presented study was to investigate the content of KYNA in 11 herbal preparations used in rheumatic diseases. MATERIALS AND METHODS The following herbs were studied: bean pericarp, birch leaf, dandelion root, elder flower, horsetail herb, nettle leaf, peppermint leaf and willow bark. An anti-rheumatic mixture of the herbs Reumatefix and Reumaflos tea were also investigated. The herbs were prepared according to producers' directions. In addition, the herbal supplement Devil's Claw containing root of Harpagophytum was used. KYNA content was measured using the high-performance liquid chromatography method, and KYNA was detected fluorometrically. RESULTS KYNA was found in all studied herbal preparations. The highest content of KYNA was found in peppermint, nettle, birch leaf and the horsetail herb. The lowest content of KYNA was found in willow bark, dandelion root and in the extract from the root of Harpagophytum. CONCLUSION These findings indicate that the use of herbal preparations containing a high level of KYNA can be considered as a supplementary measure in rheumatoid arthritis therapy, as well as in rheumatic diseases prevention.
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Affiliation(s)
- Wojciech Zgrajka
- Department of Toxicology, Institute of Rural Health, Lublin, Poland
| | - Monika Turska
- Department of Experimental and Clinical Pharmacology, Medical University, Lublin, Poland
| | - Grażyna Rajtar
- Department of Pharmacology, Medical University, Lublin, Poland
| | - Maria Majdan
- Department of Rheumatology and Connective Tissue Diseases, Medical University, Lublin, Poland
| | - Jolanta Parada-Turska
- Department of Rheumatology and Connective Tissue Diseases, Medical University, Lublin, Poland
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11
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Zhang Y, Jiang S, Xu K, Shi H, Zhou Y, Deng W, Ding L, Peng S. [Chemical constituents contained in seeds of Notopterygium franchetii]. Zhongguo Zhong Yao Za Zhi 2012; 37:941-945. [PMID: 22792794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVE To study the chemical constituents from the seeds of Notopterygium franchetii. METHOD Ethanol extracts of seeds N. franchetii were separated and purified by such methods as normal and reversed phase column chromatographies and thin-layer chromatography and structurally elucidated by MS and NMR evidences. RESULT Twenty nine compounds were separated, they were isoimperatorin (1), [3-sitosterol (2), phellopterin (3), bergapten (4), N-tetra, hexa, octacosanoylanthranilic acid (5-7), daucosterol (8), oxypeucedanin hydrate (9), umbelliferone (10), demethylfuropinnarin (11), (2S, 3S, 4R, 8E)-2-[(2'R)- 2'-hydroxydoco, trico, tetraco, entaco, hexaco sanosylamino] -octadecene-1, 3, 4-triol (12-16), (-)-oxypeucedanin (17), diosmetin (18), bergaptol-O-beta-D-glucopyranoside (19), nodakenin (20), 1'-O-beta-D-glucopyranosyl-(2R, 3S)-3-hydroxynodakenetin (21), uracil (22), decuroside V (23), 8-O-beta-D-glucopyranosyl-5-hydroxypsoralen (24), 8-O-beta-D-glucopyranosyl-5-methoxylpsoralen (25), diosmin (26), alaschanioside C (27), kynurenic acid (28) and mannitol (29). CONCLUSION All of these compounds were separated from the seeds of N. franchetii for the first time. Of them, 18, 22, 26 and 29 were firstly obtained from genus Notopterygium.
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Affiliation(s)
- Yanxia Zhang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
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12
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Szyndler J, Maciejak P, Turzyńska D, Sobolewska A, Walkowiak J, Płaźnik A. The effects of electrical hippocampal kindling of seizures on amino acids and kynurenic acid concentrations in brain structures. J Neural Transm (Vienna) 2012; 119:141-9. [PMID: 21861191 PMCID: PMC3265731 DOI: 10.1007/s00702-011-0700-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 08/08/2011] [Indexed: 11/05/2022]
Abstract
Our study demonstrated that the development of seizures during the electrically induced kindling of seizures is associated with significant changes in the concentration of kynurenic acid (KYNA) and its precursor, tryptophan (TRP). The primary finding of our study was an increase in KYNA levels and the KYNA/TRP ratio (a theoretical index of activity of the kynurenine pathway) in the amygdala and hippocampus of kindled animals. We also found decreases in the concentration of tryptophan in the hippocampus and prefrontal cortex. Changes in the concentration of KYNA and TRP in the amygdala were accompanied by a significant decrease in γ-Aminobutryic Acid (GABA) levels and an increase in the glutamate/GABA ratio. Moreover, we found a significant negative correlation between the local concentrations of KYNA and glutamate in the amygdala of kindled rats. However, there were no changes in the local concentrations of the following amino acids: glutamate, aspartate, glutamine, glycine, taurine and alanine. In conclusion, these new results suggest a modulatory influence of KYNA on the process of epileptogenesis, characterized by a negative relationship between the KYNA and glutamate systems in the amygdala.
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Affiliation(s)
- J Szyndler
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, 26/28 Krakowskie Przedmieście Street, 00-927, Warsaw, Poland.
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13
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Barth MC, Ahluwalia N, Anderson TJT, Hardy GJ, Sinha S, Alvarez-Cardona JA, Pruitt IE, Rhee EP, Colvin RA, Gerszten RE. Kynurenic acid triggers firm arrest of leukocytes to vascular endothelium under flow conditions. J Biol Chem 2009; 284:19189-95. [PMID: 19473985 PMCID: PMC2740542 DOI: 10.1074/jbc.m109.024042] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Indexed: 12/14/2022] Open
Abstract
Recent studies have demonstrated that kynurenic acid (KYNA), a compound produced endogenously by the interferon-gamma-induced degradation of tryptophan by indoleamine 2,3-dioxygenase, activates the previously orphaned G protein-coupled receptor, GPR35. This receptor is expressed in immune tissues, although its potential function in immunomodulation remains to be explored. We determined that GPR35 was most highly expressed on human peripheral monocytes. In an in vitro vascular flow model, KYNA triggered the firm arrest of monocytes to both fibronectin and ICAM-1, via beta(1) integrin- and beta(2) integrin-mediated mechanisms, respectively. Incubation of monocytes with pertussis toxin prior to use in flow experiments significantly reduced the KYNA-induced monocyte adhesion, suggesting that adhesion is triggered by a G(i)-mediated process. Furthermore, KYNA-triggered adhesion of monocytic cells was reduced by short hairpin RNA-mediated silencing of GPR35. Although GPR35 is expressed at slightly lower levels on neutrophils, KYNA induced firm adhesion of these cells to an ICAM-1-expressing monolayer as well. KYNA also elicited neutrophil shedding of surface L-selectin, another indicator of leukocyte activation. Taken together, these data suggest that KYNA could be an important early mediator of leukocyte recruitment.
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Affiliation(s)
- Marita C. Barth
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Neil Ahluwalia
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Thomas J. T. Anderson
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Gregory J. Hardy
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Sumita Sinha
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Jose A. Alvarez-Cardona
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Ivy E. Pruitt
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Eugene P. Rhee
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Richard A. Colvin
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
| | - Robert E. Gerszten
- From the Cardiology Division and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Harvard Medical School, Boston, Massachusetts 02115
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Beretta G, Vistoli G, Caneva E, Anselmi C, Maffei Facino R. Structure elucidation and NMR assignments of two new pyrrolidinyl quinoline alkaloids from chestnut honey. Magn Reson Chem 2009; 47:456-459. [PMID: 19253309 DOI: 10.1002/mrc.2407] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The complete (1)H, (13)C and (15)N NMR spectral assignments of two new alkaloids isolated from chestnut honey and structurally related to kynurenic acid have been made using 1-D and 2-D NMR techniques, including COSY, HMQC and HMBC experiments. The new compounds have been identified as 3-(2'-pyrrolidinyl)-kynurenic acid and its gamma-lactam derivative.
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Affiliation(s)
- Giangiacomo Beretta
- Department of Pharmaceutical Sciences Pietro Pratesi, University of Milan, via Mangiagalli 25, 20133 Milan, Italy.
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15
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Zakharov GA, Popov AV, Savvateeva-Popova EV, Shchegolev BF. [The role of stacking interactions in the mechanisms of binding of the glycine site of NMDA-receptor with antagonists and 3-hydroxykynurenine]. Biofizika 2008; 53:22-29. [PMID: 18488496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ab initio quantum chemical calculations of benzene dimer, benzene dimer with 5,7 clorination of one aromatic ring, 3-hydroxykynurenine, and kunurenic acid molecules situated above Phe484 aromatic ring of receptor binding site fragment were carried out in order to investigate the role of stacking interaction in the binding of agonists and antagonists with the glycine site of the NMDA receptor NR1 subunit. All calculations were done with the help of GAMESS 6.4 software with 6-31G** atomic gaussian basal functions with complete optimization of geometry and taking into account the electron correlation up to the second-order Moller-Plesset perturbation theory. It was shown that the parallel dislodged conformations of the benzene dimer is energetically most advantageous. Successive substitution of chlorine atoms for the protons of one aromatic ring in 7 and 5 positions leads to an increase in stacking-interaction energy and a mutual displacement of aromatic rings. In the case of kunurenic acid and its derivatives, which are NMDA receptor antagonists, the increase in the energy of stacking interactions leads to the strengthening of inhibition of the ion channel, whereas the 3-hydroxykynurenine molecule is neither agonist, nor antagonist for the glycine site of the NMDA receptor due to the sterical constraints.
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Abstract
KYNA, a Trp metabolite, shows neuroprotective activity against excitotoxic amino acids by antagonizing the NMDA receptor (glycine, glutamate). Here we report the identification of KYNA by a combination of ESI-MS/MS and 1D- and 2D-NMR analyses in honey varieties of arboreal origin. KYNA are absent in single-flower honeys from herbal flowers. These different distribution patterns might possibly involve an indirect plant defence mechanism against fungal pathogens and herbivorous parasites, ever-present on wild trees. The presence of KYNA in honey may explain its pain-relieving effects reported in the literature. The substance, acting in concert with honey flavonoids (COX-2 inhibitors), by antagonizing the NMDA receptor may contribute to the antinociceptive effect of honey. Moreover, kynureninates, owing to their antimicrobial properties, can favour the successful outcome of wounds and burns.
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Affiliation(s)
- Giangiacomo Beretta
- Istituto di Chimica Farmaceutica e Tossicologica Pietro Pratesi, Faculty of Pharmacy, University of Milan, Milan, Italy.
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17
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Zhuravlev AV, Shchegolev BF, Savvateeva-Popova EV, Popov AV. [Stacking-interactions in the control-gear binding of kynurenic acid with NR2A- and GluR2-subunits of glutamate ionotropic receptors]. Ross Fiziol Zh Im I M Sechenova 2007; 93:609-24. [PMID: 17850019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Kynurenine products in tryptophan metabolism are of crucial importance in modulation of neurodegenerative processes in the CNS. Kynurenic acid (KYNA): the endogenous antagonist of ionotropic glutamate receptors, displays specific affinity towards glycine site ofNMDA-receptor NR1 subunit. Mechanisms for the selective interaction of KYNA and its derivatives with other glutamate receptor subtypes are studied insufficiently. Ab initio quantum chemical calculations for KYNA-imidazole dimer, as a model for ligand interaction with His88 fragment of NR2A-subunit, along with KYNA-phenol dimer, as a model for ligand interaction with Tyr61 fragment of GluR2-subunit, were carried out in order to investigate stacking-interaction role of KYNA binding by NR2A subunit of NMDA-receptor and GluR2 subunit of AMPA-receptor. Stacking-interaction energy of KYNA-H88 for the assumed ligand orientation in the binding site is 3.0-5.0 kcal/mol and 102. kcal/mol for the optimized dimer KYNA-imidazole geometry. Stacking-interaction energy of KYNA-Tyr61 for the assumed ligand orientation in the binding site is 6.7-8.5 kcal/mol. The obtained values are comparable with the energies of hydrogen bonds. Thus, stacking-interaction should be taken into account while studing ligand glutamate receptor binding mechanisms. Stacking-interaction is evidently important for the initial ligand orientation inside the receptor binding site after which the delicate tuning of hydrogen bonding pattern is realized. On the other hand, the specific affinity of KYNA derivatives to the receptor subunits could be explained by ligand-aromatic receptor aminoacid stacking-interaction geometry difference.
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18
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Forrest CM, Mackay GM, Oxford L, Stoy N, Stone TW, Darlington LG. Kynurenine pathway metabolism in patients with osteoporosis after 2 years of drug treatment. Clin Exp Pharmacol Physiol 2007; 33:1078-87. [PMID: 17042918 DOI: 10.1111/j.1440-1681.2006.04490.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Metabolism of tryptophan along the oxidative pathway via kynurenine results in the production of quinolinic acid and kynurenic acid, which can act on glutamate receptors in peripheral tissues. We have now measured the concentrations of kynurenine pathway metabolites in the plasma of patients with osteoporosis before treatment with drugs, throughout and after 2 years of treatment with the drugs raloxifene or etidronate. Oxidative stress was assessed by measuring levels of the lipid peroxidation products malondialdehyde and 4-hydroxynonenal. Kynurenines were analysed by HPLC. Bone density was measured using dual-energy X-ray absorptiometry scans. 2. Patients with osteoporosis showed significantly lower baseline levels of 3-hydroxyanthranilic acid compared with healthy controls, but significantly higher levels of anthranilic acid and lipid peroxidation products. After 2 years treatment with etidronate and calcium, we observed significant therapeutic responses quantified by bone densitometric scanning. Significant improvements were not seen in patients treated with raloxifene. 3. In parallel, the levels of 3-hydroxyanthranilic acid, anthranilic acid and lipid peroxidation products were restored to control values by both drug treatments studied and tryptophan levels were increased significantly compared with baseline values. 4. The results suggest that tryptophan metabolism is altered in osteoporosis in a manner that could contribute to the oxidative stress and, thus, to progress of the disease. The oxidative metabolism of tryptophan (the kynurenine pathway) could represent a novel target for the development of new drugs for the treatment of osteoporosis. In addition, we noted that etidronate is a more effective drug than raloxifene, but that the simultaneous use of non-steroidal anti-inflammatory drugs may reduce the efficacy of etidronate.
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Affiliation(s)
- Caroline M Forrest
- Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
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19
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Hyun SK, Jung HA, Chung HY, Choi JS. In vitro peroxynitrite scavenging activity of 6-hydroxykynurenic acid and other flavonoids fromGingko biloba yellow leaves. Arch Pharm Res 2006; 29:1074-9. [PMID: 17225453 DOI: 10.1007/bf02969294] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As part of our research on phytochemicals that exert protective effects against diseases related to reactive nitrogen species, we have evaluated the scavenging activity of the yellow leaves of Ginkgo biloba on ONOO-. The methanol extract and ethyl acetate fraction obtained from yellow leaves of G. biloba evidenced a marked scavenging activity on authentic ONOO-. Repeated column chromatography of the active ethyl acetate soluble fraction on silica gel, Sephadex LH-20, and RP-18, resulted in the purification of 15 known compounds, including sciadopitysin (1), ginkgolide B (2), bilobalide (3), isoginkgetin (4), kaempferol (5), luteolin (6), protocatechuic acid (7), bilobetin (8), amentoflavone (9), beta-sitosterol glucopyranoside (10), kaempferol 3-O-rhamnopyranoside (11), kaempferol 3-O-glucopyranoside (12), kaempferol 3-O-[6"'-O-p-coumaroyl-beta-D-glucopyranosyl(1 --> 2)-alpha-L-rhamnopyranoside] (13), kaempferol 3-O-rutinoside (14), and 6-hydroxykynurenic acid (15). Among the compounds isolated, flavonoids (5, 6 and 11-14), protocatechuic acid (7), and 6-hydroxykynurenic acid (15) all exhibited marked scavenging activities on authentic ONOO-. The IC50 values of 5-7, 11-14 and 15 were as follows: 2.86 +/- 0.70, 2.30 +/- 0.04, 2.85 +/- 0.10, 5.60 +/- 0.47, 4.16 +/- 1.65, 2.47 +/- 0.15, 3.02 +/- 0.48, and 6.24 +/- 0.27 microM, respectively. DL-Penicillamine (IC50 = 4.98 +/- 0.27 microM) was utilized as a positive control. However, the other compounds (1-4, 8-10) exerted no effects against ONOO-.
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Affiliation(s)
- Sook Kyung Hyun
- Faculty of Food Science and Biotechnology, Pukyong National University, Busan 608-737, Korea
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20
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Nagata R, Katayama S, Ohtani KI, Tanaka H, Shimago K. Tricyclic Quinoxalinediones, Aza-kynurenic Acids, and Indole-2- Carboxylic Acids as In Vivo Active NMDA-Glycine Antagonists. Curr Top Med Chem 2006; 6:733-45. [PMID: 16719813 DOI: 10.2174/156802606776894500] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This review article describes the development of in vivo active antagonists for the glycine binding site of the N-Methyl-D-Aspartate (NMDA) receptor. There were several difficulties in identifying a class of antagonists with in vivo efficacy and only a few compounds succeeded in emerging with activity in vivo. A series of tricyclic quinoxalinediones was highly potent glycine antagonists in vitro and the derivatives having a zwitterionic moiety including SM-18400 indeed showed in vivo activity. Similarly, tricyclic indole-2-carboxylic acids having a zwitterionic moiety such as SM-31900 were also active in vivo. In fact, SM-18400 and SM-31900 exhibited efficacy in several animal stroke models using intravenous infusion protocols. The practical syntheses of SM-18400 and SM-31900 as well as the novel synthesis of moderately active glycine antagonists, tricyclic azakynurenic acids, were also developed.
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Affiliation(s)
- Ryu Nagata
- Drug Research Division and Technology Research and Development Center, Dainippon Sumitomo Pharma Co., Ltd., Konohana-Ku, Osaka, Japan.
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Moretti L, Pentikäinen OT, Settimo L, Johnson MS. Model structures of the N-methyl-D-aspartate receptor subunit NR1 explain the molecular recognition of agonist and antagonist ligands. J Struct Biol 2004; 145:205-15. [PMID: 14960371 DOI: 10.1016/j.jsb.2003.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2003] [Revised: 10/13/2003] [Indexed: 11/27/2022]
Abstract
Molecular models of the ligand-binding domain of N-methyl-d-aspartate subunit R1 (NR1) were made using the published crystal structures of rat glutamate receptor B (GluRB), the bacterial glutamate receptor (GluR0), and the glutamine-binding protein (QBP) of Escherichia coli. Separate models of NR1 were built to represent the ligand-binding conformation for agonist (glycine, d- and l-isomers of serine and alanine, and the partial agonist ligand d-cycloserine) and antagonist (5,7-dichloro-4-oxo-1,4-dihydroquinoline-2-carboxylic acid (DCKA) and E-3-(2-phenyl-2-carboxyethenyl)-4,6-dichloro-1-H-indole-2-carboxylic acid (MDL 105,519)) ligands. Side-chain conformations of residues within the NR1 ligand-binding site were selected that optimized the hydrophobic packing and hydrogen bonding among residues, while taking into account published data comparing receptor mutants with wild-type NR1. Ligands docked to the model structures provide a rational explanation for the observed differences in binding affinity and receptor activation among agonist and antagonist ligands. NR1 prefers smaller ligands (glycine, serine, and alanine) in comparison with GluRB and GluR0 that bind l-glutamate: the bulky side chain of W731 in NR1 dramatically reduces the size of the ligand-binding site, functioning to selectively restrict recognition to glycine and the d-isomers of serine and alanine. Nevertheless, many of the interactions seen for ligands bound to GluRB, GluR0, and periplasmic-binding proteins are present for the ligands docked to the model structures of NR1.
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MESH Headings
- Alanine/chemistry
- Amino Acid Sequence
- Animals
- Bacterial Proteins
- Binding Sites
- Crystallography, X-Ray
- Cycloserine/chemistry
- Databases as Topic
- Escherichia coli/metabolism
- Excitatory Amino Acid Antagonists/chemistry
- Excitatory Amino Acid Antagonists/pharmacology
- Glycine/chemistry
- Humans
- Hydrogen Bonding
- Indoles/chemistry
- Kynurenic Acid/analogs & derivatives
- Kynurenic Acid/chemistry
- Ligands
- Mice
- Models, Chemical
- Models, Molecular
- Molecular Sequence Data
- Potassium Channels/chemistry
- Proline/chemistry
- Protein Binding
- Protein Conformation
- Protein Isoforms
- Protein Structure, Tertiary
- Rats
- Receptors, AMPA/chemistry
- Receptors, Glutamate/chemistry
- Receptors, N-Methyl-D-Aspartate/agonists
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/chemistry
- Sequence Homology, Amino Acid
- Serine/chemistry
- Threonine/chemistry
- Tryptophan/chemistry
- Water/chemistry
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Affiliation(s)
- Loris Moretti
- Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistökatu 6 A, FIN-20520 Turku, Finland
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Füvesi J, Somlai C, Németh H, Varga H, Kis Z, Farkas T, Károly N, Dobszay M, Penke Z, Penke B, Vécsei L, Toldi J. Comparative study on the effects of kynurenic acid and glucosamine-kynurenic acid. Pharmacol Biochem Behav 2004; 77:95-102. [PMID: 14724046 DOI: 10.1016/j.pbb.2003.10.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Kynurenic acid (KYNA) is the only known endogenous N-methyl-D-aspartate (NMDA) receptor inhibitor and might therefore come into consideration as a therapeutic agent in certain neurobiological disorders. However, its use as a neuroprotective compound is practically excluded because KYNA does not readily cross the blood-brain barrier (BBB). We recently synthetized a new compound, glucosamine-kynurenic acid (KYNA-NH-GLUC), which is presumed to cross the BBB more easily. In this study, the effects of KYNA and KYNA-NH-GLUC on behavior and cortical activity were investigated in adult rats. The results show that (1) on intracerebroventricular application, the behavioral changes induced by KYNA and by KYNA-NH-GLUC are quite similar; (2) on intravenous administration, KYNA (25 mg/kg) has no effect on the somatosensory-evoked cortical potentials, whereas KYNA-NH-GLUC (25 mg/kg) causes transient but appreciable reductions in the amplitudes of the evoked responses within 5 min after application; and (3) the results of in vitro studies demonstrated that both KYNA and KYNA-NH-GLUC reduced the amplitudes of the field excitatory postsynaptic potentials (fEPSPs). These observations suggest that the two compounds have similar effects, but that KYNA-NH-GLUC passes the BBB much more readily than does KYNA. These results imply that the conjugated NH-GLUC is of importance in the passage across the BBB.
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Affiliation(s)
- Judit Füvesi
- Department of Comparative Physiology, University of Szeged, P.O. Box 533, H-6701, Szeged, Hungary
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Kamiński RM, Zielińska E, Dekundy A, van Luijtelaar G, Turski W. Deficit of endogenous kynurenic acid in the frontal cortex of rats with a genetic form of absence epilepsy. Pol J Pharmacol 2003; 55:741-6. [PMID: 14704470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 09/25/2003] [Indexed: 04/27/2023]
Abstract
The present studies sought to determine the concentrations of endogenous kynurenic acid (KYNA) and to measure the activity of kynurenine aminotransferases (KAT) I and II in the discrete brain regions of 3- and 6-month old WAG/Rij rats, a genetic model of absence epilepsy. Analogues experiments were performed using age-matched ACI rats, which served as a non-epileptic control. The age-dependent increase in KYNA concentration in the frontal cortex of WAG/Rij rats was considerably reduced in comparison to what was found in ACI rats. Consequently, the concentration of KYNA in the frontal cortex of epileptic rats was significantly lower than in non-epileptic controls. There were no such strain differences in other brain regions. The activities of KAT I and II also showed age-dependent increase with an exception for KAT II in the frontal cortex. Our data suggest that selective deficits of endogenous KYNA may account for increased excitability in the frontal cortex, which in turn may lead to the development of spontaneous spike-wave discharges in WAG/Rij rats.
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Affiliation(s)
- Rafał M Kamiński
- Department of Toxicology, Institute of Agricultural Medicine, Jaczewskiego 2, PL 20-950 Lublin, Poland
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Abstract
The kynurenine pathway is the main pathway for tryptophan metabolism. It generates compounds that can modulate activity at glutamate receptors and possibly nicotinic receptors, in addition to some as-yet-unidentified sites. The pathway is in a unique position to regulate other aspects of the metabolism of tryptophan to neuroactive compounds, and also seems to be a key factor in the communication between the nervous and immune systems. It also has potentially important roles in the regulation of cell proliferation and tissue function in the periphery. As a result, the pathway presents a multitude of potential sites for drug discovery in neuroscience, oncology and visceral pathology.
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Affiliation(s)
- Trevor W Stone
- Institute of Biomedical and Life Sciences, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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25
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Usov AI, Slanchev KI, Smirnova GP, Ivanova AP, Stefanov KL, Popov SS, Andreev SN. [Polar constituents of the ascidia Botryllus schlosseri]. Bioorg Khim 2002; 28:168-72. [PMID: 11962238 DOI: 10.1023/a:1015073525159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Eighteen compounds were identified by GC-MS of their trimethylsilyl derivatives in n-butanolic extract from the biomass of Botryllus schlosseri. Three of them, 5-oxoproline, 5-hydroxyhydantoin, and kinurenic acid, were found in marine invertebrates for the first time. In addition to cellulose, the biomass was also shown to contain complex water-soluble sulfated polysaccharides. These were extracted and fractionated, and sulfate content and monosaccharide composition were determined in the fractions; fucose, xylose, galactose, mannose, glucose, glucosamine, galactosamine, and uronic acids were found. Unlike several other tunicate species, Botryllus schlosseri does not seem to contain any simple galactan sulfate.
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Affiliation(s)
- A I Usov
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii prosp. 47, GSP-1 Moscow, 119991 Russia.
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26
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Manfredini S, Pavan B, Vertuani S, Scaglianti M, Compagnone D, Biondi C, Scatturin A, Tanganelli S, Ferraro L, Prasad P, Dalpiaz A. Design, synthesis and activity of ascorbic acid prodrugs of nipecotic, kynurenic and diclophenamic acids, liable to increase neurotropic activity. J Med Chem 2002; 45:559-62. [PMID: 11806707 DOI: 10.1021/jm015556r] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To improve the entry of certain drugs into brain, ascorbic acid (AA) conjugates of these drugs were synthesized and their capacity to interact with SVCT2 ascorbate transporters was explored. Kinetic studies clearly indicate that all of the conjugates were able to competitively inhibit ascorbate transport in human retinal pigment epithelial cells (HRPE). In vivo studies, in a mouse model system, demonstrate that conjugate 3 is better absorbed compared to the nonconjugated parent drug.
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27
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Hardeland R, Zsizsik BK, Poeggeler B, Fuhrberg B, Holst S, Coto-Montes A. Indole-3-pyruvic and -propionic acids, kynurenic acid, and related metabolites as luminophores and free-radical scavengers. Adv Exp Med Biol 2000; 467:389-95. [PMID: 10721080 DOI: 10.1007/978-1-4615-4709-9_49] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Chemiluminescence associated with oxidation by free radicals was investigated in an alkaline, hemin-catalysed hydrogen peroxide system, using the following tryptophan metabolites as radical scavengers: indole-3-pyruvic, indole-3-propionic, kynurenic, xanthurenic and quinaldic acids and 4-hydroxy-quinoline. Light emission from oxidation of the indolic compounds was only partially inhibited by the hydroxyl-radical scavenger DMSO, but strongly suppressed by the superoxide-anion scavenger Tiron, whereas chemi-luminescence generated from kynurenic acid was strongly inhibited by either of these compounds. Light emission from oxidation of kynurenic acid lasts for a surprisingly long period of time: At 0.4 mM and 20 degrees C, luminescence increased for 5 hours and continued at a high rate for more than a day. Comparison of structural analogues indicated that the 4-hydroxyl and carboxyl groups of kynurenic acid are essential for effective light emission, and that an additional 8-hydroxyl residue leading to an intramolecular hydrogen bond diminishes the reaction rate.
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Affiliation(s)
- R Hardeland
- Institut für Zoologie und Anthropologie, Universität Göttingen, Germany
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28
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Goda K, Hamane Y, Kishimoto R, Ogishi Y. Radical scavenging properties of tryptophan metabolites. Estimation of their radical reactivity. Adv Exp Med Biol 2000; 467:397-402. [PMID: 10721081 DOI: 10.1007/978-1-4615-4709-9_50] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Radical scavenging properties of tryptophan metabolites were estimated using their radical reactivity. Metabolites of the kynurenine and the melatonin biosynthesis pathway were mainly examined by use of a kinetical model. Their radical reactivity was determined as the reaction rate constant with a stable free radical, such as galvinoxyl; that is a phenoxy radical. The rate constants of the metabolites have a widely ranged spectrum, which can be divided into three groups. The first group (3-hydroxykynurenine, 3-hydroxyanthranilic acid, and indole-3-pyruvic acid) is more reactive than alpha-tocopherol; the reactivity of the second group (xanthurenic acid, serotonin, N-acetylserotonin) is similar to that of butylated hydroxytoluene (BHT); the third group (kynurenic acid, melatonin, and other ones) is less reactive than BHT.
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Affiliation(s)
- K Goda
- Faculty of Nutrition, Kobe Gakuin University, Japan.
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Battaglia G, La Russa M, Bruno V, Arenare L, Ippolito R, Copani A, Bonina F, Nicoletti F. Systemically administered D-glucose conjugates of 7-chlorokynurenic acid are centrally available and exert anticonvulsant activity in rodents. Brain Res 2000; 860:149-56. [PMID: 10727634 DOI: 10.1016/s0006-8993(00)01962-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have synthesized D-glucose or D-galactose esters of 7-chlorokynurenic acid (7ClKynA) as prodrugs to facilitate the transport of 7ClKynA across the blood-brain barrier. Intraperitoneal (i.p.) administration of either 7ClKynA-D-glucopyranos-6'-ylester (7ClKynA/Glu6) or 7ClKynA-D-glucopyranos-3'-yl ester (7ClKynA/Glu3) was protective against seizures induced by N-methyl-D-aspartate (NMDA) in mice, with the former drug showing the highest anticonvulsive activity. Systemic injection of equal amounts of 7ClKynA-D-galactopyranos-6'-yl ester (7ClKynA/Gal6) or free 7ClKynA did not protect against NMDA seizures. Microdialysis in freely moving rats showed the presence of significant amounts of 7ClKynA/Glu6, as well as of 7ClKynA or KynA, in cortical perfusates after i.p. injections of 7ClKynA/Glu6. In contrast, only small amounts of 7ClKynA or KynA were detected after i.p. injection of unconjugated 7ClKynA. Prodrug metabolism has also been examined in mouse cortical cultures containing both neurons and astrocytes. 7ClKynA/Glu6 and 7ClKynA/Gal6 were rapidly metabolized into 7ClKynA and KynA, whereas 7ClKynA/Glu3 was metabolized with a slower kinetics. As a result of its conversion into 7ClKynA and KynA, 7ClKynA/Glu6 protected cortical neurons against NMDA toxicity. We conclude that sugar conjugates of 7ClKynA (and perhaps of other excitatory amino acid receptor antagonists) are prodrugs of potential interest in the experimental therapy of epilepsy and acute or chronic neurodegenerative disorders.
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Abstract
This study investigated the structure-activity relationships and kinetic properties of a library of kynurenate analogues as inhibitors of 3H-L-glutamate transport into rat forebrain synaptic vesicles. The lack of inhibitory activity observed with the majority of the monocyclic pyridine derivatives suggested that the second aromatic ring of the quinoline-based compounds played a significant role in binding to the transporter. A total of two kynurenate derivatives, xanthurenate and 7-chloro-kynurenate, differing only in the carbocyclic ring substituents, were identified as potent competitive inhibitors, exhibiting Ki values of 0.19 and 0.59 mM, respectively. The Km value for L-glutamate was found to be 2.46 mM. Parallel experiments demonstrated that while none of the kynurenate analogues tested effectively inhibited the synaptosomal transport of 3H-D-aspartate, some cross-reactivity was observed with the EAA ionotropic receptors. Molecular modeling studies were carried out with the identified inhibitors and glutamate in an attempt to preliminarily define the pharmacophore of the vesicular transporter. It is hypothesized that the ability of the kynurenate analogues to bind to the transporter may be tied to the capacity of the quinoline carbocyclic ring to mimic the negative charge of the gamma-carboxylate of glutamate. A total of two low energy solution conformers of glutamate were identified that exhibited marked functional group overlap with the most potent inhibitor, xanthurenate. These results help to further refine the pharmacological specificity of the glutamate binding site on the vesicular transporter and identify a series of inhibitors with which to investigate transporter function.
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Affiliation(s)
- R D Bartlett
- Department of Pharmaceutical Sciences, University of Montana, Missoula 59812, USA
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31
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Abstract
Kynurenic acid (KA) is an excitatory amino acid receptor antagonist that is believed to play an important role in a host of diseases of the neuropsychiatric and central nervous system. A method for the determination of KA in microdialysate samples using capillary electrophoresis (CE) separation with laser-induced fluorescence (LIF) detection is described. CE is advantageous for the analysis of microdialysis samples due to its short analysis times and small sample volume requirements. Three complexation approaches were evaluated in an attempt to achieve the best limit of detection. The best approach was found to be pre-column complexation with inclusion of Zn(II) in the background electrolyte. After optimization of the zinc acetate concentration and pH, a limit of detection of 1 nM KA was achieved. However, when KA was present in the dialysate, the limit of detection increased 50-fold. Even though the endogenous levels of KA in rat brain are below this limit of detection, this methodology could be used to monitor the increase of KA levels in rat brain following dosing with its precursors, tryptophan and kynurenine.
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Affiliation(s)
- D K Hansen
- Department of Chemistry, University of Kansas, Lawrence 66047, USA
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Carling RW, Leeson PD, Moseley AM, Baker R, Foster AC, Grimwood S, Kemp JA, Marshall GR. 2-Carboxytetrahydroquinolines. Conformational and stereochemical requirements for antagonism of the glycine site on the NMDA receptor. J Med Chem 1992; 35:1942-53. [PMID: 1534583 DOI: 10.1021/jm00089a003] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
2-Carboxy-1,2,3,4-tetrahydroquinoline derivatives, derived from kynurenic acid, have been synthesized and evaluated for in vitro antagonist activity at the glycine site on the NMDA receptor. 2,3-Dihydrokynurenic acids show reduced potency relative to the parent lead compounds (Table I) possibly as a result of conformational effects. Removal of the 4-oxo group results in further reduced potency, but introduction of a cis-carboxymethyl group to the 4-position restores antagonist activity (Tables III and IV). Replacement of the keto group of 5,7-dichloro-2,3-dihydrokynurenic acid with other alternative H-bonding groups, for example cis- and trans-benzyloxycarbonyl and cis- and trans-carboxamido (Table V), gives comparable activity, but there is negligible stereoselectivity. A significant increase in potency and stereoselectivity is seen within the 4-acetate series (Table VI). The trans-4-acetic acid is significantly more potent than the corresponding lead kynurenic acid and has 100-fold greater affinity than the cis isomer. The results are consistent with a requirement in binding for a pseudoequatorially placed 2-carboxylate and clearly demonstrate the importance for binding of a correctly positioned hydrogen-bond-accepting group at the 4-position. The high-affinity binding of an anionic group in the 4-substituent binding pocket suggests that the glycine site and the neurotransmitter recognition (NMDA) site may have some features in common.
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Affiliation(s)
- R W Carling
- Department of Medicinal Chemistry, Merck Sharp and Dohme Research Laboratories, Harlow, Essex, UK
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Leeson PD, Carling RW, Moore KW, Moseley AM, Smith JD, Stevenson G, Chan T, Baker R, Foster AC, Grimwood S. 4-Amido-2-carboxytetrahydroquinolines. Structure-activity relationships for antagonism at the glycine site of the NMDA receptor. J Med Chem 1992; 35:1954-68. [PMID: 1534584 DOI: 10.1021/jm00089a004] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
trans-2-Carboxy-5,7-dichloro-4-amidotetrahydroquinolines, evolved from the lead 5,7-dichlorokynurenic acid, have been synthesized and tested for in vitro antagonist activity at the glycine site on the N-methyl-D-aspartate (NMDA) receptor. Optimization of the 4-substituent has provided antagonists having nanomolar affinity, including the urea trans-2-carboxy-5,7-dichloro-4[[(phenylamino)carbonyl]amino]-1,2,3, 4-tetrahydroquinoline (35; IC50 = 7.4 nM vs [3H]glycine binding; Kb = 130 nM for block of NMDA responses in the rat cortical slice), which is one of the most potent NMDA antagonists yet found. The absolute stereochemical requirements for binding were found to be 2S,4R, showing that, in common with other glycine-site NMDA receptor ligands, the unnatural configuration at the alpha-amino acid center is required. The preferred conformation of the trans-2,4-disubstituted tetrahydroquinoline system, as shown by X-ray crystallography and 1H NMR studies, places the 2-carboxyl pseudoequatorial and the 4-substituent pseudoaxial. Modifications of the 4-amide show that bulky substituents are tolerated and reveal the critical importance for activity of correct positioning of the carbonyl group. The high affinity of trans-2-carboxy-5,7-dichloro-4-[1-(3-phenyl-2-oxoimidazolidinyl)]- 1,2,3,4-tetrahydroquinoline (55; IC50 = 6 nM) suggests that the Z,Z conformer of the phenyl urea moiety in 35 is recognized by the receptor. Molecular modeling studies show that the 4-carbonyl groups of the kynurenic acids, the tetrahydroquinolines, and related antagonists based on N-(chlorophenyl)glycine, can interact with a single putative H-bond donor on the receptor. The results allow the establishment of a three-dimensional pharmacophore of the glycine receptor antagonist site, incorporating a newly defined bulk tolerance/hydrophobic region.
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Affiliation(s)
- P D Leeson
- Department of Medicinal Chemistry, Merck Sharp and Dohme Research Laboratories, Harlow, Essex
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Moroni F, Alesiani M, Galli A, Mori F, Pecorari R, Carlà V, Cherici G, Pellicciari R. Thiokynurenates: a new group of antagonists of the glycine modulatory site of the NMDA receptor. Eur J Pharmacol 1991; 199:227-32. [PMID: 1720099 DOI: 10.1016/0014-2999(91)90461-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Several substituted derivatives of kynurenic acid were tested on the N-methyl-D-aspartate (NMDA) receptor/ion channel complex present in the guinea pig myenteric plexus, on the binding of [3H]glycine and of [3H]N-[1-(2-thienyl)cyclohexyl]piperidine [( 3H]TCP) to rat cortical membranes and on the depolarization of mice cortical wedges induced by NMDA or quisqualic acid (QA). Kynurenic acid derivatives, having a chlorine (CI) or a fluorine atom in position 5 or 7 but not in position 6 or 8 had significantly lower IC50s than the parent compound when tested on the antagonism of glutamate-induced ileal contraction and in the glycine binding assay. A further significant increase in potency was obtained by substituting a thio group for the hydroxy group in position 4 of kynurenic acid: the IC50 was 160 +/- 20 microM of kynurenic acid and 70 +/- 15 microM of thiokynurenic acid in the myenteric plexus whereas these IC50s for glycine binding were 25 +/- 3 and 9 +/- 2 microM respectively. Several thiokynurenic acid derivatives were synthetized and showed an increased affinity for the glycine recognition site over the corresponding kynurenic acid derivatives. Glycine competitively antagonized the actions of the thiokynurenates in the ileum, in cortical wedges and on [3H]TCP binding. In this preparation, 7-Cl-thiokynurenic acid had an IC50 of 8 microM for antagonizing 10 microM NMDA-induced depolarization while 50% of the 10 microM QA depolarization was antagonized at 300 microM. Thus thiokynurenic acid derivatives seem to be a new group of potent and selective antagonists of strychnine-insensitive glycine receptors.
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Affiliation(s)
- F Moroni
- Department of Preclinical and Clinical Pharmacology, University of Florence, Italy. off
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35
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COPPINI D, BENASSI CA, MONTORSI M. Quantitative determination of tryptophan metabolites (via kynurenine) in biologic fluids. Clin Chem 1959; 5:391-401. [PMID: 13811873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
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