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Singh H, Singh H, Latief U, Tung GK, Shahtaghi NR, Sahajpal NS, Kaur I, Jain SK. Myopia, its prevalence, current therapeutic strategy and recent developments: A Review. Indian J Ophthalmol 2022; 70:2788-2799. [PMID: 35918918 PMCID: PMC9672758 DOI: 10.4103/ijo.ijo_2415_21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/12/2022] [Accepted: 02/16/2022] [Indexed: 11/05/2022] Open
Abstract
Myopia is a widespread and complex refractive error in which a person's ability to see distant objects clearly is impaired. Its prevalence rate is increasing worldwide, and as per WHO, it is projected to increase from 22% in 2000 to 52% by 2050. It is more prevalent in developed, industrial areas and affects individuals of all ages. There are a number of treatments available for the control of myopia, such as glasses, contact lenses, laser surgery, and pharmaceuticals agents. However, these treatments are less beneficial and have significant side effects. A novel molecule, 7-methylxanthine (7-MX), has been found to be a highly beneficial alternate in the treatment of myopia and excessive eye elongation. Many preclinical and clinical studies showed that 7-MX is effective for the treatment of myopia and is presently under phase II of clinical investigation. We have also investigated preclinical toxicity studies such as acute, sub-acute, sub-chronic, and chronic on rats. In these studies, 7-MX was found to be non-toxic as compared to other reported anti-myopic agents. Moreover, as an ideal drug, 7-MX is observed to have no or low toxicity, brain permeability, non-allergic, higher oral administration efficacy, and low treatment costs and thus qualifies for the long-term treatment of myopia. This review article on 7-MX as an alternative to myopia treatment will highlight recent findings from well-designed preclinical and clinical trials and propose a potential future therapy.
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Affiliation(s)
- Harjeet Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, Punjab, India
- Department of Pharmacy, Government Polytechnic College, Amritsar, Punjab, India
| | - Harmanpreet Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Uzma Latief
- Center for Basic and Translational Research in Health Science, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Gurleen Kaur Tung
- Center for Basic and Translational Research in Health Science, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Navid Reza Shahtaghi
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, Punjab, India
| | | | - Inderjit Kaur
- Department of Ophthalmology, Baba Farid University of Health Sciences, Faridkot, Punjab, India
| | - Subheet Kumar Jain
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, Punjab, India
- Center for Basic and Translational Research in Health Science, Guru Nanak Dev University, Amritsar, Punjab, India
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Andries A, Feyaerts A, Mekahli D, Van Schepdael A. Quantification of allantoin and other metabolites of the purine degradation pathway in human plasma samples using a newly developed HILIC‐LC‐MS/MS method. Electrophoresis 2022; 43:1010-1018. [DOI: 10.1002/elps.202100265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 01/10/2022] [Accepted: 01/17/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Asmin Andries
- Department of Pharmaceutical and Pharmacological Sciences Pharmaceutical Analysis KU Leuven – University of Leuven Leuven Belgium
| | - Alan Feyaerts
- Department of Pharmaceutical and Pharmacological Sciences Pharmaceutical Analysis KU Leuven – University of Leuven Leuven Belgium
| | - Djalila Mekahli
- Department of Development and Regeneration Laboratory of Pediatrics KU Leuven – University of Leuven Leuven Belgium
- Department of Pediatric Nephrology University Hospitals Leuven Leuven Belgium
| | - Ann Van Schepdael
- Department of Pharmaceutical and Pharmacological Sciences Pharmaceutical Analysis KU Leuven – University of Leuven Leuven Belgium
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Singh H, Singh H, Sahajpal NS, Paul S, Kaur I, Jain SK. Sub-chronic and chronic toxicity evaluation of 7-methylxanthine: a new molecule for the treatment of myopia. Drug Chem Toxicol 2020; 45:1383-1394. [PMID: 33076712 DOI: 10.1080/01480545.2020.1833904] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Myopia (nearsightedness) is a vision disorder with a blurring of far objects, affect millions worldwide. 7-methylxanthine (7-MX) is a molecule that is presently under clinical investigation for the treatment of myopia. In the present study, we have investigated sub-chronic and chronic toxicity of 7-MX in comparison to other clinically used methylxanthines i.e., caffeine and theobromine as per OECD guidelines 408 and 452. 7-MX was administered orally for 90 days at three different doses of 250, 500, and 1000 mg/kg for sub-chronic toxicity evaluation, and at a limit dose of 1000 mg/kg in 180 days chronic toxicity evaluation in rats. In sub-chronic treatment, 7-MX showed no mortality and signs for toxicity in any group, whereas 10% and 40% mortality with signs for toxicity were observed in caffeine and theobromine treated groups, respectively. A similar, safety profile was observed with 7-MX in 180 days of chronic toxicity study. Further, to confirm any morphological changes in organs; ultrasound and X-rays analysis were performed and no changes in the size of organs, cyst formation, fluid retention, or crystal formation was observed. Thus, the repeated dose study of 7-MX for 180 days may augment the possibility of using 7-MX clinically for the safe and effective treatment of myopia.
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Affiliation(s)
- Harjeet Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Harmanpreet Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | | | - Surinder Paul
- Department of Pathology, Government Medical College, Amritsar, India
| | - Inderjit Kaur
- Department of Opthalmology, Baba Farid University of Health Sciences, Faridkot, Punjab
| | - Subheet Kumar Jain
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
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Akram M, Asghar MN, Saleem Khan M, Shahid S, Abdur Rahman HM, Nadeem I. Development and validation of an economical uric acid-Fe3+/Fe2+-ferrozine-based colorimetric assay to estimate uric acid level of pure and biological samples. Biosci Biotechnol Biochem 2020; 84:1967-1974. [DOI: 10.1080/09168451.2020.1781593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Abstract
This work presents the development and validation of a simple, rapid, and cost-effective spectrophotometric method for quantitative analysis of uric acid in biological samples. The method relies upon uric acid-led reduction of Fe(III) to Fe(II) of sample/standard solutions which stoichiometrically engages ferrozine to form a magenta-colored complex. Different parameters including pH, metal and chelator concentrations, temperature, etc., were optimized for the maximum intensity and stability of the complex. The uric acid concentrations of synthetic/plasma solutions were determined by comparing the color intensity of Fe(ferrozine)32+ complex produced by test solution with the standard curve formed by known uric acid concentrations. The method was validated in accordance with ICH guidelines and subjected to human plasma analysis. The results obtained were compared with a reference (enzymatic) method which revealed that there was no significant difference between the two methods at 95% confidence level. The method is highly specific, precise, linear, accurate, and robust.
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Affiliation(s)
- Maryam Akram
- Department of Chemistry, Forman Christian College (A Chartered University), Lahore, Pakistan
| | - Muhammad Nadeem Asghar
- Department of Chemistry, Forman Christian College (A Chartered University), Lahore, Pakistan
| | - Maria Saleem Khan
- Department of Chemistry, Forman Christian College (A Chartered University), Lahore, Pakistan
| | - Sammia Shahid
- Department of Chemistry, School of Science and Technology, University of Management and Technology, Lahore, Pakistan
| | | | - Iram Nadeem
- Department of Chemistry, COMSATS University Islamabad, Lahore Campus, Pakistan
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Singh H, Sahajpal NS, Singh H, Vanita V, Roy P, Paul S, Singh SK, Kaur I, Jain SK. Pre-clinical and cellular toxicity evaluation of 7-methylxanthine: an investigational drug for the treatment of myopia. Drug Chem Toxicol 2019; 44:575-584. [DOI: 10.1080/01480545.2019.1635615] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Harjeet Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Nikhil Shri Sahajpal
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Harmanpreet Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Vanita Vanita
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, India
| | - Partha Roy
- Department of Biotechnology, Indian Institute of Technology, Roorkee, India
| | - Surinder Paul
- Department of Pathology, Government Medical College, Amritsar, India
| | - Shashank Kumar Singh
- Cancer Pharmacology Division, Indian Institute of Integrative Medicine, Jammu, India
| | - Inderjit Kaur
- Department of Ophthalmology, Baba Farid University of Health Sciences, Punjab, India
| | - Subheet Kumar Jain
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
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Polyák P, Rácz P, Rózsa P, Nagy GN, Vértessy BG, Pukánszky B. The novel technique of vapor pressure analysis to monitor the enzymatic degradation of PHB by HPLC chromatography. Anal Biochem 2017; 521:20-27. [DOI: 10.1016/j.ab.2017.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Revised: 01/03/2017] [Accepted: 01/05/2017] [Indexed: 11/16/2022]
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Ultra-high performance liquid chromatography with ultraviolet and tandem mass spectrometry for simultaneous determination of metabolites in purine pathway of rat plasma. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1036-1037:84-92. [DOI: 10.1016/j.jchromb.2016.09.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 09/12/2016] [Accepted: 09/16/2016] [Indexed: 11/22/2022]
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Characterizing Blood Metabolomics Profiles Associated with Self-Reported Food Intakes in Female Twins. PLoS One 2016; 11:e0158568. [PMID: 27355821 PMCID: PMC4927065 DOI: 10.1371/journal.pone.0158568] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/19/2016] [Indexed: 12/15/2022] Open
Abstract
Using dietary biomarkers in nutritional epidemiological studies may better capture exposure and improve the level at which diet-disease associations can be established and explored. Here, we aimed to identify and evaluate reproducibility of novel biomarkers of reported habitual food intake using targeted and non-targeted metabolomic blood profiling in a large twin cohort. Reported intakes of 71 food groups, determined by FFQ, were assessed against 601 fasting blood metabolites in over 3500 adult female twins from the TwinsUK cohort. For each metabolite, linear regression analysis was undertaken in the discovery group (excluding MZ twin pairs discordant [≥1 SD apart] for food group intake) with each food group as a predictor adjusting for age, batch effects, BMI, family relatedness and multiple testing (1.17x10-6 = 0.05/[71 food groups x 601 detected metabolites]). Significant results were then replicated (non-targeted: P<0.05; targeted: same direction) in the MZ discordant twin group and results from both analyses meta-analyzed. We identified and replicated 180 significant associations with 39 food groups (P<1.17x10-6), overall consisting of 106 different metabolites (74 known and 32 unknown), including 73 novel associations. In particular we identified trans-4-hydroxyproline as a potential marker of red meat intake (0.075[0.009]; P = 1.08x10-17), ergothioneine as a marker of mushroom consumption (0.181[0.019]; P = 5.93x10-22), and three potential markers of fruit consumption (top association: apple and pears): including metabolites derived from gut bacterial transformation of phenolic compounds, 3-phenylpropionate (0.024[0.004]; P = 1.24x10-8) and indolepropionate (0.026[0.004]; P = 2.39x10-9), and threitol (0.033[0.003]; P = 1.69x10-21). With the largest nutritional metabolomics dataset to date, we have identified 73 novel candidate biomarkers of food intake for potential use in nutritional epidemiological studies. We compiled our findings into the DietMetab database (http://www.twinsuk.ac.uk/dietmetab-data/), an online tool to investigate our top associations.
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Arthur KL, Eiceman GA, Reynolds JC, Creaser CS. Analysis of Supramolecular Complexes of 3-Methylxanthine with Field Asymmetric Waveform Ion Mobility Spectrometry Combined with Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:800-809. [PMID: 26914231 DOI: 10.1007/s13361-016-1351-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 01/22/2016] [Accepted: 01/23/2016] [Indexed: 06/05/2023]
Abstract
Miniaturised field asymmetric waveform ion mobility spectrometry (FAIMS), combined with mass spectrometry (MS), has been applied to the study of self-assembling, noncovalent supramolecular complexes of 3-methylxanthine (3-MX) in the gas phase. 3-MX forms stable tetrameric complexes around an alkali metal (Na(+), K(+)) or ammonium cation, to generate a diverse array of complexes with single and multiple charge states. Complexes of (3-MX)n observed include: singly charged complexes where n = 1-8 and 12 and doubly charged complexes where n = 12-24. The most intense ions are those associated with multiples of tetrameric units, where n = 4, 8, 12, 16, 20, 24. The effect of dispersion field on the ion intensities of the self-assembled complexes indicates some fragmentation of higher order complexes within the FAIMS electrodes (in-FAIMS dissociation), as well as in-source collision induced dissociation within the mass spectrometer. FAIMS-MS enables charge state separation of supramolecular complexes of 3-MX and is shown to be capable of separating species with overlapping mass-to-charge ratios. FAIMS selected transmission also results in an improvement in signal-to-noise ratio for low intensity complexes and enables the visualization of species undetectable without FAIMS.
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Affiliation(s)
- Kayleigh L Arthur
- Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK
| | - Gary A Eiceman
- Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK
- Department of Chemistry and Biochemistry, New Mexico State University, MSC 3C, P.O. Box 3001, Las Cruces, NM, 88003-8001, USA
| | - James C Reynolds
- Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.
| | - Colin S Creaser
- Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.
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Zare HR, Ghanbari Z, Nasirizadeh N, Benvidi A. Simultaneous determination of adrenaline, uric acid, and cysteine using bifunctional electrocatalyst of ruthenium oxide nanoparticles. CR CHIM 2013. [DOI: 10.1016/j.crci.2013.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Talik P, Krzek J, Ekiert RJ. Analytical Techniques Used for Determination of Methylxanthines and their Analogues—Recent Advances. SEPARATION AND PURIFICATION REVIEWS 2012. [DOI: 10.1080/15422119.2011.569047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Babu RS, Prabhu P, Narayanan SS. Selective electrooxidation of uric acid in presence of ascorbic acid at a room temperature ionic liquid/nickel hexacyanoferarrate nanoparticles composite electrode. Colloids Surf B Biointerfaces 2011; 88:755-63. [DOI: 10.1016/j.colsurfb.2011.08.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 08/05/2011] [Accepted: 08/12/2011] [Indexed: 11/25/2022]
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13
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Electrochemical Sensor Based on Oxidation of 2,8-Dihydroxyadenine to Monitor DNA Damage in Calf Thymus DNA. ELECTROANAL 2011. [DOI: 10.1002/elan.201000753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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15
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Simultaneous LC–UV–MS–MS Analysis of Nine Pivotal Metabolites in Human Serum: Application to Studies of Impaired Glucose Tolerance. Chromatographia 2011. [DOI: 10.1007/s10337-010-1833-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Kasawar G, Razzak M, Zaheer Z, Farooqui M. VALIDATED RP-LC-MS/MS METHOD FOR THE SIMULTANEOUS DETERMINATION OF ALLOPURINOL AND ITS MAJOR METABOLITE, OXYPURINOL, IN HUMAN PLASMA. J LIQ CHROMATOGR R T 2011. [DOI: 10.1080/10826076.2011.534692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Gajanan Kasawar
- a Post Graduate and Research Centre, Maulana Azad College , Aurangabad, India
| | - Mushtaq Razzak
- a Post Graduate and Research Centre, Maulana Azad College , Aurangabad, India
| | - Zahid Zaheer
- b Y. B. Chavan College of Pharmacy, Dr. Rafiq Zakaria Campus , Rauza Bagh, Aurangabad, India
| | - Mazahar Farooqui
- a Post Graduate and Research Centre, Maulana Azad College , Aurangabad, India
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Hason S, Stepankova S, Kourilova A, Vetterl V, Lata J, Fojta M, Jelen F. Simultaneous Electrochemical Monitoring of Metabolites Related to the Xanthine Oxidase Pathway Using a Grinded Carbon Electrode. Anal Chem 2009; 81:4302-7. [DOI: 10.1021/ac900201g] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stanislav Hason
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
| | - Sona Stepankova
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
| | - Alena Kourilova
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
| | - Vladimir Vetterl
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
| | - Jan Lata
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
| | - Miroslav Fojta
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
| | - Frantisek Jelen
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Kralovopolska 135, CZ-612 65 Brno, Czech Republic, Department of Internal Medicine and Hepatogastroenterology, University Hospital and Faculty of Medicine, Masaryk University, CZ-625 00 Brno, Czech Republic
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Ly SY, Lee CH, Jung YS. Voltammetric Bioassay of Caffeine using Sensor Implant. Neuromolecular Med 2009; 11:20-7. [DOI: 10.1007/s12017-008-8057-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 12/11/2008] [Indexed: 10/21/2022]
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Jin CH, Lee JW, Row KH. Prediction of elution bandwidth for purine compounds by a retention model in reversed-phase HPLC with linear-gradient elution. J Sep Sci 2008; 31:23-9. [PMID: 18064619 DOI: 10.1002/jssc.200700244] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In reversed-phase liquid chromatography, the retention mechanism of solute has been studied under linearly programmed gradient mobile-phase conditions. The separation of a mixture of four purine compounds (purine, theobromine, theophylline, and caffeine) was considered as a practical case in two binary mobile phase systems, water/methanol and water/acetonitrile. The retention model which describes how the retention factor is related to the mobile-phase composition has been developed in various mathematical forms to predict the retention time in both linear and gradient elutions. For a pulse injection of sample, two important factors, the retention time and the bandwidth of solute, might be computable to predict the elution profiles estimated by the distribution function, such as the Gaussian distribution function. In this work, a prediction method based on the analogue of the retention model was proposed to calculate the bandwidth in linear gradient elutions. Band broadening was caused by the different migration velocities of the front and rear ends of the solute band in a chromatographic column. Therefore, the migration behaviors of the front and rear ends of the solute band were explained with the same retention model which had been used to predict the retention time of solute. For the well retained solutes, theophylline and caffeine, the predicted bandwidth and experimentally obtained bandwidth showed good agreement in both isocratic and gradient elutions.
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Affiliation(s)
- Chun Hua Jin
- ERC for Advanced Bioseparation Technology and Department of Chemical Engineering, Inha University, Incheon, Korea
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Quiming NS, Denola NL, Saito Y, Catabay AP, Jinno K. Chromatographic Behavior of Uric Acid and Methyl Uric Acids on a Diol Column in HILIC. Chromatographia 2008. [DOI: 10.1365/s10337-008-0559-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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21
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Chi Y, Dong Y, Chen G. Investigation on the electrochemiluminescent behaviors of oxypurinol in alkaline Ru(bpy)32+ solution using a flow injection analytical system. Electrochem commun 2007. [DOI: 10.1016/j.elecom.2006.09.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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22
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Diculescu VC, Piedade JAP, Oliveira-Brett AM. Electrochemical behaviour of 2,8-dihydroxyadenine at a glassy carbon electrode. Bioelectrochemistry 2006; 70:141-6. [PMID: 16713382 DOI: 10.1016/j.bioelechem.2006.03.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Indexed: 11/25/2022]
Abstract
The electrochemical behaviour of 2,8-dihydroxyadenine (2,8-DHA)- the main adenine oxidation product- has been investigated over a wide pH range at a glassy carbon electrode (GCE) using cyclic, differential pulse and square wave voltammetry. The oxidation of 2,8-DHA is a quasi-reversible process, pH dependent and occurs with the formation of a main oxidation product, P(2,8-DHA), that strongly adsorbs on the electrode surface. The reduction of 2,8-DHA also occurs and is a reversible process in the absence of molecular oxygen. In electrolytes with pH between 4 and 9 two consecutive reversible charge transfer reactions were identified. However, it was observed that O(2) interfered with the reductive electron transfer process of 2,8-DHA and that, in the presence of oxygen, the reduction of 2,8-DHA occurs at less negative potentials than in the absence of oxygen.
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Affiliation(s)
- Victor C Diculescu
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal
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Kachoosangi R, Banks C, Compton R. Simultaneous Determination of Uric Acid and Ascorbic Acid Using Edge Plane Pyrolytic Graphite Electrodes. ELECTROANAL 2006. [DOI: 10.1002/elan.200603470] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
BACKGROUND The aim of the study was to measure the content of methylated purines that appear as admixtures in uric acid stones. METHODS We analyzed urinary calculi from 48 residents of Western Pomerania who underwent surgery at the urology ward in Szczecin. Stone samples were dissolved in 0.1 mol/L NaOH. Extracts were diluted in 50 mmol/L KH(2)PO(4) and analyzed by reversed-phase HPLC with ultraviolet detection and use of a gradient of methanol concentration and pH. RESULTS Uric acid was the main component of 9 stones. All 9 showed admixtures of 9 other purine derivatives: endogenous purine breakdown products (xanthine, hypoxanthine, and 2,8-dihydroxyadenine) and exogenous methyl derivatives of uric acid and xanthine (1-, 3-, and 7-methyluric acid; 1,3-dimethyluric acid; and 3- and 7-methylxanthine). Amounts of these purine derivatives ranged from the limit of detection to 12 mg/g of stone weight and showed a strong positive correlation (Spearman rank correlation coefficients, 0.63-0.94) with the uric acid content of the samples. The main methylated purine in the stones was 1-methyluric acid. CONCLUSIONS Urinary purines at concentrations below their saturation limits may coprecipitate in samples supersaturated with uric acid and appear as admixtures in urinary stones. The amount of each purine depends on its average urinary excretion, similarity to the chemical structure of uric acid, and concentration of the latter in the stone. These findings suggest that purines in stones represent a substitutional solid solution with uric acid as solvent. Methylxanthines, which are ubiquitous components of the diet, drugs, and uric acid calculi, may be involved in the pathogenesis of urolithiasis.
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Affiliation(s)
- Krzysztof Safranow
- Department of Biochemistry and Chemistry, Pomeranian Medical University, Szczecin, Poland.
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