School Of Basic And Applied Sciences

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Author: search.filters.author.Gupta, S.K

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    Drug-metabolizing enzymes: role in drug resistance in cancer
    (Springer, 2020) Kaur, G; Gupta, S.K; Singh, P; Ali, V; Kumar, V; Verma, M.
    Although continuous researches are going on for the discovery of new chemotherapeutic agents, resistance to these anticancer agents has made it really difficult to reach the fruitful results. There are many causes for this resistance that are being studied by the researchers across the world, but still, success is far because there are several factors that are going along unattended or have been studied less. Drug-metabolizing enzymes (DMEs) are one of these factors, on which less study has been conducted. DMEs include Phase I and Phase II enzymes. Cytochrome P450s (CYPs) are major Phase I enzymes while glutathione-S-transferases (GSTs), UDP-glucuronosyltransferases (UGTs), dihydropyrimidine dehydrogenases are the major enzymes belonging to the Phase II enzymes. These enzymes play an important role in detoxification of the xenobiotics as well as the metabolism of drugs, depending upon the tissue in which they are expressed. When present in tumorous tissues, they cause resistance by metabolizing the drugs and rendering them inactive. In this review, the role of these various enzymes in anticancer drug metabolism and the possibilities for overcoming the resistance have been discussed. � 2020, Federaci�n de Sociedades Espa�olas de Oncolog�a (FESEO).
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    4,6-Diphenylpyrimidine Derivatives as Dual Inhibitors of Monoamine Oxidase and Acetylcholinesterase for the Treatment of Alzheimer's Disease
    (American Chemical Society, 2019) Kumar, B; Dwivedi, A.R; Sarkar, B; Gupta, S.K; Krishnamurthy, S; Mantha, Anil K; Parkash, Jyoti; Kumar, Vinod
    Alzheimer's disease (AD) is a neurodegenerative disorder with multifactorial pathogenesis. Monoamine oxidase (MAO) and acetylcholinesterase enzymes (AChE) are potential targets for the treatment of AD. A total of 15 new propargyl containing 4,6-diphenylpyrimidine derivatives were synthesized and screened for the MAO and AChE inhibition activities along with ROS production inhibition and metal-chelation potential. All the synthesized compounds were found to be selective and potent inhibitors of MAO-A and AChE enzymes at nanomolar concentrations. VB1 was found to be the most potent MAO-A and BuChE inhibitor with IC 50 values of 18.34 ± 0.38 nM and 0.666 ± 0.03 μM, respectively. It also showed potent AChE inhibition with an IC 50 value of 30.46 ± 0.23 nM. Compound VB8 was found to be the most potent AChE inhibitor with an IC 50 value of 9.54 ± 0.07 nM and displayed an IC 50 value of 1010 ± 70.42 nM against the MAO-A isoform. In the cytotoxic studies, these compounds were found to be nontoxic to the human neuroblastoma SH-SY5Y cells even at 25 μM concentration. All the compounds were found to be reversible inhibitors of MAO-A and AChE enzymes. In addition, these compounds also showed good neuroprotective properties against 6-OHDA- and H 2 O 2 -induced neurotoxicity in SH-SY5Y cells. All the compounds accommodate nicely to the hydrophobic cavity of MAO-A and AChE enzymes. In the molecular dynamics simulation studies, both VB1 and VB8 were found to be stable in the respective cavities for 30 ns. Thus, 4,6-diphenylpyrimidine derivatives can act as promising leads in the development of dual-acting inhibitors targeting MAO-A and AChE enzymes for the treatment of Alzheimer's disease. © 2018 American Chemical Society.
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    Stability and tunable electronic structure of planar phosphorus nanotubes
    (American Institute of Physics, 2019) Singh, S; Kaur, S; Gupta, S.K; Kumar, Ashok; Srivastava, S.
    The stability and electronic properties of planar phosphorous nanotubes with different chirality are investigated within the formulation of density functional theory. Armchair phosphorous nanotube (APNT) is found to be energetically most favorable with very small formation energy (0.08 eV). APNT also possess highest tensile strength (∼2 GPa), among the considered nanotubes. Armchair and helical PNTs are semiconducting while zigzag PNT is metallic in nature. We found that the application of strain and external electric field greatly modifies the electronic band structure of given PNTs. We believe that planar APNT can be realized and its tunable electronic properties may be useful for nanoelectronics. © 2019 Author(s).