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Shyam M, Kumar S, Singh V. Unlocking Opportunities for Mycobacterium leprae and Mycobacterium ulcerans. ACS Infect Dis 2024; 10:251-269. [PMID: 38295025 PMCID: PMC10862552 DOI: 10.1021/acsinfecdis.3c00371] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/25/2023] [Accepted: 12/28/2023] [Indexed: 02/02/2024]
Abstract
In the recent decade, scientific communities have toiled to tackle the emerging burden of drug-resistant tuberculosis (DR-TB) and rapidly growing opportunistic nontuberculous mycobacteria (NTM). Among these, two neglected mycobacteria species of the Acinetobacter family, Mycobacterium leprae and Mycobacterium ulcerans, are the etiological agents of leprosy and Buruli ulcer infections, respectively, and fall under the broad umbrella of neglected tropical diseases (NTDs). Unfortunately, lackluster drug discovery efforts have been made against these pathogenic bacteria in the recent decade, resulting in the discovery of only a few countable hits and majorly repurposing anti-TB drug candidates such as telacebec (Q203), P218, and TB47 for current therapeutic interventions. Major ignorance in drug candidate identification might aggravate the dramatic consequences of rapidly spreading mycobacterial NTDs in the coming days. Therefore, this Review focuses on an up-to-date account of drug discovery efforts targeting selected druggable targets from both bacilli, including the accompanying challenges that have been identified and are responsible for the slow drug discovery. Furthermore, a succinct discussion of the all-new possibilities that could be alternative solutions to mitigate the neglected mycobacterial NTD burden and subsequently accelerate the drug discovery effort is also included. We anticipate that the state-of-the-art strategies discussed here may attract major attention from the scientific community to navigate and expand the roadmap for the discovery of next-generation therapeutics against these NTDs.
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Affiliation(s)
- Mousumi Shyam
- Department
of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mersa, Ranchi, Jharkhand 835215, India
| | - Sumit Kumar
- Holistic
Drug Discovery and Development (H3D) Centre, University of Cape Town, Rondebosch 7701, South Africa
| | - Vinayak Singh
- Holistic
Drug Discovery and Development (H3D) Centre, University of Cape Town, Rondebosch 7701, South Africa
- South
African Medical Research Council Drug Discovery and Development Research
Unit, University of Cape Town, Rondebosch 7701, South Africa
- Institute
of Infectious Disease and Molecular Medicine (IDM), University of Cape Town, Observatory 7925, Cape Town, South Africa
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Shyam M, Bhattacharje G, Daniel C, Kumar A, Yadav P, Mukherjee P, Singh S, Das AK, Narender T, Singh A, Jayaprakash V, Bhakta S. Rationally Designed Novel Phenyloxazoline Synthase Inhibitors: Chemical Synthesis and Biological Evaluation to Accelerate the Discovery of New Antimycobacterial Antibiotics. Molecules 2023; 28:8115. [PMID: 38138601 PMCID: PMC10745776 DOI: 10.3390/molecules28248115] [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] [Received: 10/30/2023] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
The uncontrolled spread of drug-resistant tuberculosis (DR-TB) clinical cases necessitates the urgent discovery of newer chemotypes with novel mechanisms of action. Here, we report the chemical synthesis of rationally designed novel transition-state analogues (TSAs) by targeting the cyclization (Cy) domain of phenyloxazoline synthase (MbtB), a key enzyme of the conditionally essential siderophore biosynthesis pathway. Following bio-assay-guided evaluation of TSA analogues preferentially in iron-deprived and iron-rich media to understand target preferentiality against a panel of pathogenic and non-pathogenic mycobacteria strains, we identified a hit, i.e., TSA-5. Molecular docking, dynamics, and MMPBSA calculations enabled us to comprehend TSA-5's stable binding at the active site pocket of MbtB_Cy and the results imply that the MbtB_Cy binding pocket has a strong affinity for electron-withdrawing functional groups and contributes to stable polar interactions between enzyme and ligand. Furthermore, enhanced intracellular killing efficacy (8 μg/mL) of TSA-5 against Mycobacterium aurum in infected macrophages is noted in comparison to moderate in vitro antimycobacterial efficacy (64 μg/mL) against M. aurum. TSA-5 also demonstrates whole-cell efflux pump inhibitory activity against Mycobacterium smegmatis. Identification of TSA-5 by focusing on the modular MbtB_Cy domain paves the way for accelerating novel anti-TB antibiotic discoveries.
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Affiliation(s)
- Mousumi Shyam
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215, India;
- Mycobacteria Research Laboratory, School of Natural Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK;
| | - Gourab Bhattacharje
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India; (G.B.); (A.K.D.)
| | - Chris Daniel
- Mycobacteria Research Laboratory, School of Natural Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK;
| | - Amrendra Kumar
- Division of Medicinal & Process Chemistry, CSIR-Central Drug Research Institute, Sector 10 Janakipuram Extension, Sitapur Road, Lucknow 226031, India; (A.K.); (P.Y.); (T.N.)
| | - Pragya Yadav
- Division of Medicinal & Process Chemistry, CSIR-Central Drug Research Institute, Sector 10 Janakipuram Extension, Sitapur Road, Lucknow 226031, India; (A.K.); (P.Y.); (T.N.)
| | - Piyali Mukherjee
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, CV Raman Avenue, Bengaluru 560012, India; (P.M.); (S.S.); (A.S.)
| | - Samsher Singh
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, CV Raman Avenue, Bengaluru 560012, India; (P.M.); (S.S.); (A.S.)
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India; (G.B.); (A.K.D.)
| | - Tadigoppula Narender
- Division of Medicinal & Process Chemistry, CSIR-Central Drug Research Institute, Sector 10 Janakipuram Extension, Sitapur Road, Lucknow 226031, India; (A.K.); (P.Y.); (T.N.)
| | - Amit Singh
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, CV Raman Avenue, Bengaluru 560012, India; (P.M.); (S.S.); (A.S.)
| | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215, India;
| | - Sanjib Bhakta
- Mycobacteria Research Laboratory, School of Natural Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK;
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Shyam M, Shilkar D, Rakshit G, Jayaprakash V. Approaches for Targeting the Mycobactin Biosynthesis Pathway for Novel Anti-tubercular Drug Discovery: Where We Stand. Expert Opin Drug Discov 2022; 17:699-715. [PMID: 35575503 DOI: 10.1080/17460441.2022.2077328] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Several decades of antitubercular drug discovery efforts have focused on novel antitubercular chemotherapies. However, recent efforts have greatly shifted towards countering extremely/multi/total drug-resistant species. Targeting the conditionally essential elements inside Mycobacterium is a relatively new approach against tuberculosis and has received lackluster attention. The siderophore, Mycobactin, is a conditionally essential molecule expressed by mycobacteria in iron-stress conditions. It helps capture the micronutrient iron, essential for the smooth functioning of cellular processes. AREAS COVERED The authors discuss opportunities to target the conditionally essential pathways to help develop newer drugs and prolong the shelf life of existing therapeutics, emphasizing the bottlenecks in fast-tracking antitubercular drug discovery. EXPERT OPINION While the lack of iron supply can cripple bacterial growth and multiplication, excess iron can cause oxidative overload. Constant up-regulation can strain the bacterial synthetic machinery, further slowing its growth. Mycobactin synthesis is tightly controlled by a genetically conserved mega enzyme family via up-regulation (HupB) or down-regulation (IdeR) based on iron availability in its microenvironment. Furthermore, the recycling of siderophores by the MmpL-MmpS4/5 orchestra provides endogenous drug targets to beat the bugs with iron-toxicity contrivance. These processes can be exploited as chinks in the armor of Mycobacterium and be used for new drug development.
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Affiliation(s)
- Mousumi Shyam
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, India
| | - Deepak Shilkar
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, India
| | - Gourav Rakshit
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, India
| | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, India
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Shyam M, Verma H, Bhattacharje G, Mukherjee P, Singh S, Kamilya S, Jalani P, Das S, Dasgupta A, Mondal A, Das AK, Singh A, Brucoli F, Bagnéris C, Dickman R, Basavanakatti VN, Naresh Babu P, Sankaran V, Dev A, Sinha BN, Bhakta S, Jayaprakash V. Mycobactin Analogues with Excellent Pharmacokinetic Profile Demonstrate Potent Antitubercular Specific Activity and Exceptional Efflux Pump Inhibition. J Med Chem 2022; 65:234-256. [PMID: 34981940 DOI: 10.1021/acs.jmedchem.1c01349] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study, we have designed and synthesized pyrazoline analogues that partially mimic the structure of mycobactin, to address the requirement of novel therapeutics to tackle the emerging global challenge of antimicrobial resistance (AMR). Our investigation resulted in the identification of novel lead compounds 44 and 49 as potential mycobactin biosynthesis inhibitors against mycobacteria. Moreover, candidates efficiently eradicated intracellularly surviving mycobacteria. Thermofluorimetric analysis and molecular dynamics simulations suggested that compounds 44 and 49 bind to salicyl-AMP ligase (MbtA), a key enzyme in the mycobactin biosynthetic pathway. To the best of our knowledge, these are the first rationally designed mycobactin inhibitors to demonstrate an excellent in vivo pharmacokinetic profile. In addition, these compounds also exhibited more potent whole-cell efflux pump inhibition than known efflux pump inhibitors verapamil and chlorpromazine. Results from this study pave the way for the development of 3-(2-hydroxyphenyl)-5-(aryl)-pyrazolines as a new weapon against superbug-associated AMR challenges.
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Affiliation(s)
- Mousumi Shyam
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India.,Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Harshita Verma
- Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Gourab Bhattacharje
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | | | | | - Sujit Kamilya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Avenue, Bangalore 560012, India
| | - Pushpendu Jalani
- Microbiology Division, CSIR-Central Drug Research Institute, Sector 10 Janakipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Swetarka Das
- Microbiology Division, CSIR-Central Drug Research Institute, Sector 10 Janakipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Arunava Dasgupta
- Microbiology Division, CSIR-Central Drug Research Institute, Sector 10 Janakipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Abhishake Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Avenue, Bangalore 560012, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | | | - Federico Brucoli
- Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, U.K
| | - Claire Bagnéris
- Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Rachael Dickman
- Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, University of London, London WC1N 1AX, U.K
| | | | | | - Vadivelan Sankaran
- Eurofins Advinus Limited, 21 & 22, Peenya Industrial area, Bengaluru 560058, India
| | - Abhimanyu Dev
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India
| | - Barij Nayan Sinha
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India
| | - Sanjib Bhakta
- Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India
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Shyam M, Shilkar D, Verma H, Dev A, Sinha BN, Brucoli F, Bhakta S, Jayaprakash V. The Mycobactin Biosynthesis Pathway: A Prospective Therapeutic Target in the Battle against Tuberculosis. J Med Chem 2020; 64:71-100. [PMID: 33372516 DOI: 10.1021/acs.jmedchem.0c01176] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The alarming rise in drug-resistant clinical cases of tuberculosis (TB) has necessitated the rapid development of newer chemotherapeutic agents with novel mechanisms of action. The mycobactin biosynthesis pathway, conserved only among the mycolata family of actinobacteria, a group of intracellularly surviving bacterial pathogens that includes Mycobacterium tuberculosis, generates a salicyl-capped peptide mycobactin under iron-stress conditions in host macrophages to support the iron demands of the pathogen. This in vivo essentiality makes this less explored mycobactin biosynthesis pathway a promising endogenous target for novel lead-compounds discovery. In this Perspective, we have provided an up-to-date account of drug discovery efforts targeting selected enzymes (MbtI, MbtA, MbtM, and PPTase) from the mbt gene cluster (mbtA-mbtN). Furthermore, a succinct discussion on non-specific mycobactin biosynthesis inhibitors and the Trojan horse approach adopted to impair iron metabolism in mycobacteria has also been included in this Perspective.
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Affiliation(s)
- Mousumi Shyam
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215 Jharkhand, India.,Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Deepak Shilkar
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215 Jharkhand, India
| | - Harshita Verma
- Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Abhimanyu Dev
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215 Jharkhand, India
| | - Barij Nayan Sinha
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215 Jharkhand, India
| | - Federico Brucoli
- Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, U.K
| | - Sanjib Bhakta
- Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, U.K
| | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi 835215 Jharkhand, India
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Shyam M, Johnson TH, Rachana RR, Varatharajan R, Mound LA. Redescription and lectotype designation of <em>Gynaikothrips <em>microchaetus Ananthakrishnan & Jagadish (Thysanoptera: Phlaeothripidae). Zootaxa 2019; 4701:zootaxa.4701.6.8. [PMID: 32229921 DOI: 10.11646/zootaxa.4701.6.8] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Indexed: 11/04/2022]
Abstract
Gynaikothrips microchaetus Ananthakrishnan and Jagadish (1969) was described from Dharwar in Karnataka, and until now has been known only from southern India (Ananthakrishnan & Sen 1980). The original description was based on an unspecified number of syntypes, with no depositary indicated. However, one of the authors (R. Varatharajan) acquired four slides that are labelled by Ananthakrishnan as this species and bear the same collection details as given in the original description. These are assumed to be syntypes, and one female is here designated as lectotype. The other three slides are of males and are considered as paralectotypes. Further, during extensive surveys for thrips at Dampa Tiger Reserve, Mizoram (23.320 N 92.130 E) and Manipur University campus (24.820 N 93.900 E) during 2014-18, we have collected both sexes of this species from the leaves of Ficus curtipes. The freshly collected specimens were mounted onto microscope slides in Canada balsam, and identified using the keys provided by Ananthakrishnan and Sen (1980). Hence, the species is illustrated and re-described with additional features, based on the type material together with freshly collected specimens from north eastern India, Manipur and Mizoram. The following abbreviations are used for pronotal setae: am-anteromarginals; aa-anteroangulars; pa-posteroangulars; ml-midlaterals; po-postocular; epim-epimerals; abdominal tergite IX setae S1, S2 & S3-setal pairs I, II and III respectively (S1 nearest the mid-line).
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Affiliation(s)
- M Shyam
- Centre of Advanced Study in Life Sciences, Manipur University.
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Shyam M, Dev A, Sinha BN, Jayaprakash V. Scaffold Based Search on the Desferithiocin Archetype. Mini Rev Med Chem 2019; 19:1564-1576. [PMID: 30827237 DOI: 10.2174/1389557519666190301151151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/17/2018] [Accepted: 01/21/2019] [Indexed: 01/19/2023]
Abstract
Iron overload disorder and diseases where iron mismanagement plays a crucial role require orally available iron chelators with favourable pharmacokinetic and toxicity profile. Desferrithiocin (DFT), a tridentate and orally available iron chelator has a favourable pharmacokinetic profile but its use has been clinically restricted due to its nephrotoxic potential. The chemical architecture of the DFT has been naturally well optimized for better iron chelation and iron clearance from human biological system. Equally they are also responsible for its toxicity. Hence, subsequent research has been devoted to develop a non-nephrotoxic analogue of DFT without losing its iron clearance ability. The review has been designed to classify the compounds reported till date and to discuss the structure activity relationship with reference to modifications attempted at different positions over pyridine and thiazoline ring of DFT. Compounds are clustered under two major classes: (i) Pyridine analogues and (ii) phenyl analogue and further each class has been further subdivided based on the presence or absence and the number of hydroxy functional groups present over pyridine or phenyl ring of the DFT analogues. Finally a summary and few insights into the development of newer analogues are provided.
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Affiliation(s)
- Mousumi Shyam
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| | - Abhimanyu Dev
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| | - Barij Nayan Sinha
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
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Molla A, Ranjan S, Rao MS, Dar AH, Shyam M, Jayaprakash V, Hussain S. Borax Catalysed Domino Synthesis of Highly Functionalised Spirooxindole and Chromenopyridine Derivatives: X‐Ray Structure, Hirshfeld Surface Analysis and Molecular Docking Studies. ChemistrySelect 2018. [DOI: 10.1002/slct.201801867] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Aniruddha Molla
- Department of ChemistryIndian Institute of Technology Patna, Bihar 801 106
| | - Subham Ranjan
- Department of Chemical SciencesIndian Institute of Science Education and Research (IISER) KolkataMohanpur Campus Mohanpur 741 246 India
| | | | | | - Mousumi Shyam
- Department of Pharmaceutical Sciences and TechnologyBirla Institute of Technology Mesra Ranchi 835 215 India
| | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences and TechnologyBirla Institute of Technology Mesra Ranchi 835 215 India
| | - Sahid Hussain
- Department of ChemistryIndian Institute of Technology Patna, Bihar 801 106
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Abstract
India is the largest manufacturer of tractors in the world. They are used for primary and secondary tillage operations and as a means of transportation. Vibration in tractor driving can cause deafness and disorders of the spinal column and stomach. The effect of implements on tractor ride is not well understood in India. The present study was undertaken to quantify ride vibration of a low horsepower tractor-implement system. Tractor ride vibration levels have been measured at the person-seat interface along three mutually perpendicular axes, longitudinal, lateral and vertical, under different operating conditions. It was observed that the acceleration levels increased as forward speed of travel increased under most of the operating conditions. There was no conclusive difference in measured acceleration levels on a tar-macadam road and a farm road during transport mode. The measured ride vibration levels under different operating conditions were evaluated as per ISO 2631/1 (1985), Geneva, and BS 6841 (1987), London, standards. On the basis of this study, it is concluded that the exposure time for the tractor operator should not exceed 2.5 h during ploughing and harrowing operations. Increasing exposure time may cause severe discomfort, pain and injury.
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Affiliation(s)
- C R Mehta
- Agricultural Energy and Power Division, Central Institute of Agricultural Engineering, Bhopal, India.
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Singh CP, Shyam M, Tuli SK. Nucleus-nucleus multiplicity distributions and quantum chromodynamics. Phys Rev C Nucl Phys 1989; 40:1716-1721. [PMID: 9966158 DOI: 10.1103/physrevc.40.1716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Shyam M, Verma S, Pathak B. Performance of a low-horsepower diesel engine with a blend of rapeseed oil and conventional diesel fuel. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/0167-5826(87)90004-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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