1
|
Witty DR, Alvaro G, Derjean D, Giblin GMP, Gunn K, Large C, Macpherson DT, Morisset V, Owen D, Palmer J, Rugiero F, Tate S, Hinckley CA, Naik H. Discovery of Vixotrigine: A Novel Use-Dependent Sodium Channel Blocker for the Treatment of Trigeminal Neuralgia. ACS Med Chem Lett 2020; 11:1678-1687. [PMID: 32945812 PMCID: PMC7488392 DOI: 10.1021/acsmedchemlett.0c00263] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022] Open
Abstract
Drugs that block voltage-gated sodium channels (NaVs) have utility in treating conditions including pain, epilepsy, and cardiac arrhythmias and as anesthetics (Lancet Neurol.20109413424; Expert Opin. Ther. Pat.201020755779). The identification of compounds with improved efficacy and safety is a key aim for the discovery of improved NaV blocking drugs (Comprehensive Medicinal Chemistry III; (Elsevier, 2017; pp 131-175). We report the identification of a novel class of brain penetrant and voltage-gated sodium channel blockers, leading to the discovery of vixotrigine, a use-dependent sodium channel blocker with activity in in vivo models of pain. Vixotrigine has excellent physiocochemical properties for drug development, and both preclinical and clinical data support a safety profile suitable for potential use in neuropathic pain and other conditions. It has shown efficacy in a Phase II study for pain associated with trigeminal neuralgia.
Collapse
Affiliation(s)
- David R. Witty
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Giuseppe Alvaro
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Dominique Derjean
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Gerard M. P. Giblin
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Kevin Gunn
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Charles Large
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - David T. Macpherson
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Valerie Morisset
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Davina Owen
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Joanne Palmer
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Francois Rugiero
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Simon Tate
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | | | - Himanshu Naik
- Biogen
Inc., 225 Binney Street, Cambridge, Massachusetts 02142,
United States
| |
Collapse
|
2
|
Wu Y, Wang N, Zhang T, Yan Z, Xu B, Inoa J, Xing Y. Iodine‐Mediated Synthesis of Methylthio‐Substituted Catechols from Cyclohexanones. Adv Synth Catal 2019. [DOI: 10.1002/adsc.201900069] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yue‐Hua Wu
- Technical Institute of Physics and Chemistry & University of Chinese Academy of SciencesChinese Academy of Sciences Beijing 100190 People's Republic of China
| | - Nai‐Xing Wang
- Technical Institute of Physics and Chemistry & University of Chinese Academy of SciencesChinese Academy of Sciences Beijing 100190 People's Republic of China
| | - Tong Zhang
- Technical Institute of Physics and Chemistry & University of Chinese Academy of SciencesChinese Academy of Sciences Beijing 100190 People's Republic of China
| | - Zhan Yan
- Technical Institute of Physics and Chemistry & University of Chinese Academy of SciencesChinese Academy of Sciences Beijing 100190 People's Republic of China
| | - Bao‐Cai Xu
- School of Food and Chemical EngineeringBeijing Technology and Business University Beijing 100048 People's Republic of China
| | - Joan Inoa
- Department of ChemistryWilliam Paterson University of New Jersey New Jersey 07470 United States
| | - Yalan Xing
- Department of ChemistryWilliam Paterson University of New Jersey New Jersey 07470 United States
| |
Collapse
|
3
|
Deng S, Cheng Z, Ingalls C, Kontes F, Yan J, Belvedere S. Synthesis of 2,3,4,5-Tetrahydrobenzo[1,4]thiazepines via N-Acyliminium Cyclization. Org Process Res Dev 2017. [DOI: 10.1021/acs.oprd.7b00260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shixian Deng
- ARMGO Pharma, Inc., 777 Old Saw Mill River Road, Tarrytown, New York 10591, United States
- Department
of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, United States
| | - Zhenzhuang Cheng
- ARMGO Pharma, Inc., 777 Old Saw Mill River Road, Tarrytown, New York 10591, United States
| | - Charles Ingalls
- ARMGO Pharma, Inc., 777 Old Saw Mill River Road, Tarrytown, New York 10591, United States
| | - Ferenc Kontes
- ARMGO Pharma, Inc., 777 Old Saw Mill River Road, Tarrytown, New York 10591, United States
| | - Jiaming Yan
- ARMGO Pharma, Inc., 777 Old Saw Mill River Road, Tarrytown, New York 10591, United States
| | - Sandro Belvedere
- ARMGO Pharma, Inc., 777 Old Saw Mill River Road, Tarrytown, New York 10591, United States
| |
Collapse
|
4
|
Katte TA, Reekie TA, Jorgensen WT, Kassiou M. The Formation of Seven-Membered Heterocycles under Mild Pictet–Spengler Conditions: A Route to Pyrazolo[3,4]benzodiazepines. J Org Chem 2016; 81:4883-9. [DOI: 10.1021/acs.joc.6b00710] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Timothy A. Katte
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Tristan A. Reekie
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - William T. Jorgensen
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Michael Kassiou
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| |
Collapse
|
5
|
Kotha S, Deodhar D, Khedkar P. Diversity-oriented synthesis of medicinally important 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) derivatives and higher analogs. Org Biomol Chem 2015; 12:9054-91. [PMID: 25299735 DOI: 10.1039/c4ob01446d] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1,2,3,4-Tetrahydroisoquinoline-3-carboxylic acid (Tic) is a constrained analog of phenylalanine (Phe). The Tic unit has been identified as a core structural element present in several peptide-based drugs and forms an integral part of various biologically active compounds. This report covers the biological significance of the Tic core and provides a detailed account of various synthetic approaches available for the construction of Tic derivatives. Along with the traditional methods such as the Pictet-Spengler and Bischler-Nepieralski reactions, we cover various recent approaches such as enyne metathesis, [2 + 2 + 2] cycloaddition and the Diels-Alder reaction to generate Tic derivatives. In addition, syntheses of higher analogs of Tic are also discussed.
Collapse
Affiliation(s)
- Sambasivarao Kotha
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai - 400 076, India.
| | | | | |
Collapse
|
6
|
Pesnot T, Gershater MC, Ward JM, Hailes HC. Phosphate mediated biomimetic synthesis of tetrahydroisoquinoline alkaloids. Chem Commun (Camb) 2011; 47:3242-4. [DOI: 10.1039/c0cc05282e] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
7
|
Choi YS, Pennington CL, Wood TD. Stable isotope labeling method targeting terminal tyrosine for relative peptide quantitation using mass spectrometry. Anal Biochem 2010; 401:15-21. [PMID: 20188058 DOI: 10.1016/j.ab.2010.02.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 02/17/2010] [Accepted: 02/20/2010] [Indexed: 01/13/2023]
Abstract
Many neuropeptides lack suitable amino acid residues for modification by existing selective isotope labeling methods and use in relative quantitation by mass spectrometry. To address this issue, a new stable isotope labeling method that targets tyrosine residues by coupling with light cysteine (d(0)) or heavy cysteine (d(2)) in the presence of tyrosinase was developed. Optimal derivatization conditions for 1microM leucine-enkephalin were achieved when 10mM cysteine and 200U/ml tyrosinase at pH 6.8 to 7.2 were used for a 60-min incubation period at room temperature. Under these conditions, leucine-enkephalin present at concentrations as low as 125nM was successfully labeled. When comparisons between the lightly labeled (d(0)) and heavily labeled (d(2)) forms were made, a discrepancy between the actual concentration ratio and the raw peak intensity ratio was observed; this is due to the overlap of an isotopic peak of the d(0) with the monoisotopic peak of d(2). Fortunately, this discrepancy can be corrected by one of two simple computational approaches described. The quantitative labeling of this method to neuropeptides with the terminal tyrosine was confirmed and provides an alternative when other selective isotope-coded affinity tagging methods are not suitable.
Collapse
Affiliation(s)
- Yong Seok Choi
- Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14260, USA
| | | | | |
Collapse
|
8
|
Simon JD, Peles D, Wakamatsu K, Ito S. Current challenges in understanding melanogenesis: bridging chemistry, biological control, morphology, and function. Pigment Cell Melanoma Res 2009; 22:563-79. [PMID: 19627559 DOI: 10.1111/j.1755-148x.2009.00610.x] [Citation(s) in RCA: 263] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Melanin is a natural pigment produced within organelles, melanosomes, located in melanocytes. Biological functions of melanosomes are often attributed to the unique chemical properties of the melanins they contain; however, the molecular structure of melanins, the mechanism by which the pigment is produced, and how the pigment is organized within the melanosome remains to be fully understood. In this review, we examine the current understanding of the initial chemical steps in the melanogenesis. Most natural melanins are mixtures of eumelanin and pheomelanin, and so after presenting the current understanding of the individual pigments, we focus on the mixed melanin systems, with a critical eye towards understanding how studies on individual melanin do and do not provide insight in the molecular aspects of their structures. We conclude the review with a discussion of important issues that must be addressed in future research efforts to more fully understand the relationship between molecular and functional properties of this important class of natural pigments.
Collapse
Affiliation(s)
- John D Simon
- Department of Chemistry, Duke University, Durham, NC, USA.
| | | | | | | |
Collapse
|
9
|
Wakamatsu K, Ohtara K, Ito S. Chemical analysis of late stages of pheomelanogenesis: conversion of dihydrobenzothiazine to a benzothiazole structure. Pigment Cell Melanoma Res 2009; 22:474-86. [PMID: 19493317 DOI: 10.1111/j.1755-148x.2009.00580.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Pheomelanogenesis is a complex pathway that starts with the oxidation of tyrosine (or DOPA, 3,4-dihydroxyphenylalanine) by tyrosinase in the presence of cysteine, which results in the production of 5-S-cysteinyldopa and its isomers. Beyond that step, relatively little has been clarified except for a possible intermediate produced, dihydro-1,4-benzothiazine-3-carboxylic acid (DHBTCA). We therefore carried out a detailed study on the course of pheomelanogenesis using DOPA and cysteine and the physiological enzyme tyrosinase. To elucidate the later stages of pheomelanogenesis, chemical degradative methods of reductive hydrolysis with hydroiodic acid and alkaline peroxide oxidation were applied. The results show that: (1) DHBTCA accumulates after the disappearance of the cysteinyldopa isomers, (2) DHBTCA is then oxidized by a redox exchange with dopaquinone to form ortho-quinonimine, which leads to the production of pheomelanin with a benzothiazine moiety, and (3) the benzothiazine moiety gradually degrades to form a benzothiazole moiety. This latter process is consistent with the much higher ratio of benzothiazole-derived units in human red hair than in mouse yellow hair. These findings may be relevant to the (photo)toxic effects of pheomelanin.
Collapse
Affiliation(s)
- Kazumasa Wakamatsu
- Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi, Japan
| | | | | |
Collapse
|
10
|
Youn SW. THE PICTET-SPENGLER REACTION: EFFICIENT CARBON-CARBON BOND FORMING REACTION IN HETEROCYCLIC SYNTHESIS. ORG PREP PROCED INT 2006. [DOI: 10.1080/00304940609356447] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
11
|
Manini P, Napolitano A, d'Ischia M. Reactions of d-glucose with phenolic amino acids: further insights into the competition between Maillard and Pictet–Spengler condensation pathways. Carbohydr Res 2005; 340:2719-27. [PMID: 16229826 DOI: 10.1016/j.carres.2005.09.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 09/26/2005] [Accepted: 09/28/2005] [Indexed: 02/02/2023]
Abstract
The reactions of 5-S-cysteinyldopa, L-alpha-methyldopa and DL-m-tyrosine with D-glucose were investigated at 90 degrees C in phosphate buffer at pH ranging from 5.0 to 9.0. Whereas gave mainly the double Maillard condensation product N,N'-bis(1''-deoxy-D-fructos-1''-yl)-5-S-cysteinyldopa, as an inseparable mixture of beta-D-fructopyranosyl and alpha,beta-D-fructofuranosyl derivatives, 2 and 3 gave both Maillard and Pictet-Spengler products, although to different extents and with different regio- and stereochemistry. A peculiar pattern of reactivity was displayed by which gave, besides the Maillard product and the expected 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline C-1 diastereoisomeric pairs, the unprecedented 7,8-dihydroxy-1,2,3,4-tetrahydroisoquinoline derivative via the ortho cyclization pathway. Pictet-Spengler cyclization of 2 and 3 proceeded with Felkin-Anh-type asymmetric induction, favouring the 1R isomer throughout the pH range 5.0-9.0. These results, which highlight the first example of carbohydrate-derived 7,8-dihydroxytetrahydroisoquinoline, provide new insights into the factors governing competition between Maillard and Pictet-Spengler condensation pathways.
Collapse
Affiliation(s)
- Paola Manini
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte Sant'Angelo, Via Cinthia 4, I-80126 Naples, Italy
| | | | | |
Collapse
|
12
|
Manini P, Panzella L, Tedesco I, Petitto F, Russo GL, Napolitano A, Palumbo A, d'Ischia M. Tetrahydrobiisoquinoline Derivatives by Reaction of Dopamine with Glyoxal: A Novel Potential Degenerative Pathway of Catecholamines under Oxidative Stress Conditions. Chem Res Toxicol 2004; 17:1190-8. [PMID: 15377152 DOI: 10.1021/tx034268q] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In 0.1 M phosphate buffer, pH 7.4, dopamine reacts with glyoxal, a cytotoxic and genotoxic alpha-oxoaldehyde produced by oxidative degradation of carbohydrates, to give three main products, two of which could be isolated and identified as the isomeric tetrahydrobiisoquinolines 1 and 2 by extensive two-dimensional NMR and mass spectrometric analysis. Time course studies indicated that 1 is the first intermediate in the process and changes slowly to 2 via an unstable species that escaped all efforts at isolation and structural identification. Products 1 and 2 were detected also among the species formed by the interaction of dopamine with oxidized carbohydrates, such as glucose, ribose, and fructose. Mechanistic evidence suggests that the formation of 1 proceeds by an unusual reaction pathway involving intramolecular cyclization of a double Schiff base intermediate followed by glyoxal-induced oxidation of the resulting octahydrobiisoquinoline intermediate (4). Subsequent conversion of 1 to 2 would involve a complex redox mechanism depending on an initial oxidation step. Product 2 was only poorly toxic to PC12 cells, whereas its methylated derivative 3 was as toxic as salsolinol, an established neurotoxin. Overall, these results throw light on a novel pathway of dopamine modification of potential relevance to the mechanisms underlying neurodegenerative changes in Parkinson's disease and other disorders characterized by a prooxidant state.
Collapse
Affiliation(s)
- Paola Manini
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, I-80126 Naples, Italy
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Palumbo A, Napolitano A, d'Ischia M. Nitrocatechols versus nitrocatecholamines as novel competitive inhibitors of neuronal nitric oxide synthase: lack of the aminoethyl side chain determines loss of tetrahydrobiopterin-antagonizing properties. Bioorg Med Chem Lett 2002; 12:13-6. [PMID: 11738563 DOI: 10.1016/s0960-894x(01)00680-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
6-Nitrocatecholamines were recently described as novel neuronal nitric oxide synthase inhibitors competing with both L-arginine and tetrahydrobiopterin (BH(4)). We report now that simple nitrocatechols are also competitive inhibitors, lacking however BH(4)-antagonizing properties. It is argued that 6-nitrocatecholamines interact with the L-arginine- and BH(4)-binding sites through the nitrocatechol and aminoethyl moieties, respectively.
Collapse
Affiliation(s)
- Anna Palumbo
- Laboratory of Biochemistry, Zoological Station "Anton Dohrn", Villa Comunale I-80121, Naples, Italy
| | | | | |
Collapse
|
14
|
Napolitano A, Di Donato P, Prota G. Zinc-catalyzed oxidation of 5-S-cysteinyldopa to 2,2'-bi(2H-1,4-benzothiazine): tracking the biosynthetic pathway of trichochromes, the characteristic pigments of red hair. J Org Chem 2001; 66:6958-66. [PMID: 11597214 DOI: 10.1021/jo010320g] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Trichochromes, the peculiar pigments of red human hair, featuring the Delta(2,2)(')-bi(2H-1,4-benzothiazine) skeleton, are known to arise from cysteinyldopas, mainly the 5-S-isomer (5). However, the mode of formation and the direct precursors have remained largely undefined. To fill this gap, we investigated the oxidation of 5 in air or with chemical and enzymatic agents under biomimetic conditions. In the presence of zinc ions, which occur in epidermal tissues at significant concentrations, the reaction course is diverted toward the formation of a labile 3-carboxy-2H-1,4-benzothiazine intermediate (11), which was identified by direct NMR analysis. Structural formulation was supported by characterization of the analogous compound 13 isolated from oxidation of the model 5-methyl-3-S-cysteinylcatechol (12) after methylation. In the further stages of the oxidation, diastereomeric 2,2'-bi(2H-1,4-benzothiazine) 15 and 14 were obtained from 5 and 12, respectively, the reaction proceeding at a higher rate and to a greater extent in the presence of acids. The dimers were shown to readily convert to each other in the presence of acids. In the case of the methylated dimers 14, a 2,2'-bi(4H-1,4-benzothiazine) intermediate (16) was isolated and characterized. In acidic media, trichochrome C (1a), the most abundant in red human hair, was smoothly formed from aerial oxidation of 15, and under similar conditions, trichochrome-related products (17 and 18) were obtained from 14 prior to or after methylation. The presence of 1a and precursors 5 and 15 was investigated by HPLC analysis of red hair samples following mild proteolytic digestion. On the basis of these data, a likely biosynthetic route to trichochrome pigments of red human hair is depicted.
Collapse
Affiliation(s)
- A Napolitano
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, I-80126 Naples, Italy
| | | | | |
Collapse
|
15
|
Manini P, d'Ischia M, Prota G. An unusual decarboxylative Maillard reaction between L-DOPA and D-glucose under biomimetic conditions: factors governing competition with Pictet-Spengler condensation. J Org Chem 2001; 66:5048-53. [PMID: 11463255 DOI: 10.1021/jo010078d] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In 0.1 M phosphate buffer at pH 7.4 and 37 degrees C, the tyrosine metabolite L-3,4-dihydroxyphenylalanine (L-DOPA) reacts smoothly with D-glucose to afford, besides diastereoisomeric tetrahydroisoquinolines 1 and 2 by Pictet-Spengler condensation, a main product shown to be the unexpected decarboxylated Amadori compound N-(1-deoxy-D-fructos-1-yl)-dopamine (3). Under similar conditions, dopamine gave only tetrahydroisoquinoline products 4 and 5, whereas L-tyrosine gave exclusively the typical Amadori compound 6. Fe(3+) and Cu(2+) ions, which accumulate in relatively high levels in parkinsonian substantia nigra, both inhibited the formation of 3. Cu(2+) ions also inhibited the formation of 1 and 2 to a similar degree, whereas Fe(3+) ions increased the yields of 1 and 2. Apparently, the formation of 3 would not be compatible with a simple decarboxylation of the initial Schiff base adduct, but would rather involve the decarboxylative decomposition of a putative oxazolidine-5-one intermediate assisted by the catechol ring. These results report the first decarboxylative Maillard reaction between an amino acid and a carbohydrate under biomimetic conditions and highlight the critical role of transition metal ions in the competition with Pictet-Spengler condensation.
Collapse
Affiliation(s)
- P Manini
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 4, I-80126 Naples, Italy
| | | | | |
Collapse
|
16
|
Dehn DL, Claffey DJ, Duncan MW, Ruth JA. Nicotine and cotinine adducts of a melanin intermediate demonstrated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Chem Res Toxicol 2001; 14:275-9. [PMID: 11258976 DOI: 10.1021/tx000205l] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pigmentation is a major factor in the incorporation of many drugs into hair. In an attempt to elucidate potential mechanisms of drug-melanin interaction, melanin was synthesized in vitro in the presence of nicotine, which we have shown to have a substantial interaction with melanin, and cotinine, a primary nicotine metabolite. L-DOPA, a precursor of eumelanin, was oxidized and oligomerized with tyrosinase. Nicotine, cotinine, and/or their deuterated analogues were added to the oligomerization reaction mixture in a 10:1 L-DOPA:drug ratio. A black precipitate formed within 60 min. Aliquots were removed from the incubation mixture at 60, 120, and 360 min. MALDI-TOF MS determinations were carried out on each sample to provide a mean and standard error for the masses of interest. Internal calibration allowed accurate mass measurement of the products. A careful comparison of the spectra of samples prepared both with and without drug indicated the presence of masses corresponding to the protonated drug, melanin oligomers, and nicotine or continine adducts of the monomeric melanin intermediate dopaquinone (DOPAQ). Additional support for the presence of drug-melanin adducts was provided by employing deuterated analogues of nicotine and L-DOPA in the reaction and observing that the masses shifted accordingly. Structures of the adducts were further confirmed by select ion gating and postsource decay analysis.
Collapse
Affiliation(s)
- D L Dehn
- Program in Molecular and Environmental Toxicology and Biochemical Mass Spectrometry Facility, School of Pharmacy, The University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
| | | | | | | |
Collapse
|