Jaspreet Kaur

Publications of Jaspreet Kaur

• In silico screening, structure-activity relationship, and biologic evaluation of selective pteridine reductase inhibitors targeting visceral leishmaniasis.

  Authors: Jaspreet Kaur, Pranav Kumar, Sargam Tyagi, Richa Pathak, Sanjay Batra, Prashant Singh, Neeloo Singh

  Antimicrobial agents and chemotherapy. 02/2011; 55(2):659-66.

  In this study we utilized the concept of rational drug design to identify novel compounds with optimal selectivity, efficacy and safety, which would bind to the target enzyme pteridine reductase 1In this study we utilized the concept of rational drug design to identify novel compounds with optimal selectivity, efficacy and safety, which would bind to the target enzyme pteridine reductase 1 (PTR1) in Leishmania parasites. Twelve compounds afforded from Baylis-Hillman chemistry were docked by using the QUANTUM program into the active site of Leishmania donovani PTR1 homology model. The biological activity for these compounds was estimated in green fluorescent protein-transfected L. donovani promastigotes, and the most potential analogue was further investigated in intracellular amastigotes. Structure-activity relationship based on homology model drawn on our recombinant enzyme was substantiated by recombinant enzyme inhibition assay and growth of the cell culture. Flow cytometry results indicated that 7-(4-chlorobenzyl)-3-methyl-4-(4-trifluoromethyl-phenyl)-3,4,6,7,8,9-hexahydro-pyrimido[1,2-a]pyrimidin-2-one (compound 7) was 10 times more active on L. donovani amastigotes (50% inhibitory concentration [IC(50)] = 3 μM) than on promastigotes (IC(50) = 29 μM). Compound 7 exhibited a K(i) value of 0.72 μM in a recombinant enzyme inhibition assay. We discovered that novel pyrimido[1,2-a]pyrimidin-2-one systems generated from the allyl amines afforded from the Baylis-Hillman acetates could have potential as a valuable pharmacological tool against the neglected disease visceral leishmaniasis.

• Bioinformatic Analysis of Leishmania donovani Long-Chain Fatty Acid-CoA Ligase as a Novel Drug Target.

  Authors: Jaspreet Kaur, Rameshwar Tiwari, Arun Kumar, Neeloo Singh

  Molecular biology international. 01/2011; 2011:278051.

  Fatty acyl-CoA synthetase (fatty acid: CoA ligase, AMP-forming; (EC 6.2.1.3)) catalyzes the formation of fatty acyl-CoA by a two-step process that proceeds through the hydrolysis of pyrophosphate.Fatty acyl-CoA synthetase (fatty acid: CoA ligase, AMP-forming; (EC 6.2.1.3)) catalyzes the formation of fatty acyl-CoA by a two-step process that proceeds through the hydrolysis of pyrophosphate. Fatty acyl-CoA represents bioactive compounds that are involved in protein transport, enzyme activation, protein acylation, cell signaling, and transcriptional control in addition to serving as substrates for beta oxidation and phospholipid biosynthesis. Fatty acyl-CoA synthetase occupies a pivotal role in cellular homeostasis, particularly in lipid metabolism. Our interest in fatty acyl-CoA synthetase stems from the identification of this enzyme, long-chain fatty acyl-CoA ligase (LCFA) by microarray analysis. We found this enzyme to be differentially expressed by Leishmania donovani amastigotes resistant to antimonial treatment. In the present study, we confirm the presence of long-chain fatty acyl-CoA ligase gene in the genome of clinical isolates of Leishmania donovani collected from the disease endemic area in India. We predict a molecular model for this enzyme for in silico docking studies using chemical library available in our institute. On the basis of the data presented in this work, we propose that long-chain fatty acyl-CoA ligase enzyme serves as an important protein and a potential target candidate for development of selective inhibitors against leishmaniasis.

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• Molecular docking, structure-activity relationship and biological evaluation of the anticancer drug monastrol as a pteridine reductase inhibitor in a clinical isolate of Leishmania donovani.

  Authors: Jaspreet Kaur, Shyam Sundar, Neeloo Singh

  The Journal of antimicrobial chemotherapy. 08/2010; 65(8):1742-8.

  Using the pteridine reductase (PTR1) enzyme of Leishmania as the target, the objective of our study was to find a drug candidate that can enter the clinical development process after being evaluatedUsing the pteridine reductase (PTR1) enzyme of Leishmania as the target, the objective of our study was to find a drug candidate that can enter the clinical development process after being evaluated for safety and efficacy in animals. Monastrol (R) and (S) enantiomers were docked using the QUANTUM program into the active site of a Leishmania donovani PTR1 (LdPTR1) homology model. A structure-activity relationship based on a homology model of a recombinant enzyme was substantiated by a recombinant enzyme inhibition assay. We adapted an L. donovani (transfected with green fluorescent protein) intramacrophage amastigote screening assay as a cellular model for leishmaniasis. Furthermore, since the clinicopathological features and immunopathological mechanisms of visceral leishmaniasis (VL) in a hamster model are remarkably similar to those of human disease, systemic infection of hamsters with L. donovani was utilized to collect in vivo data for monastrol. Both monastrol (R) and (S) enantiomers fit well in the ligand-binding pocket of LdPTR1. Monastrol exhibits a K(i) value of 0.428 microM in the recombinant enzyme inhibition assay. We confirm monastrol as a potent inhibitor of PTR1 in Leishmania; it inhibits proliferation of amastigotes with an IC(50) (50% inhibitory concentration) of 10 microM in macrophage cultures infected with an L. donovani clinical isolate, with no host cytotoxicity. We also show that in experimental animals, oral administration of a 5 mg/kg dose of monastrol on two alternate days inhibits 50% of parasite growth, giving therapeutic backing to the use of monastrol as a potent antileishmanial in human VL cases. To our knowledge, this is the first report presenting monastrol as a potent oral antileishmanial.

• Leishmania donovani: oral therapy with glycosyl 1,4-dihydropyridine analogue showing apoptosis like phenotypes targeting pteridine reductase 1 in intracellular amastigotes.

  Authors: Jaspreet Kaur, Nasib Singh, Biswajit Kumar Singh, Anuradha Dube, Rama Pati Tripathi, Prashant Singh, Neeloo Singh

  Experimental parasitology. 02/2010; 125(3):310-4.

  Glycosyl 1,4-dihydropyridine analogue (2,6-dimethyl-4-(3-O-benzyl-1,2-O-isopropylidene-beta-l-threo pentofuranos-4-yl)-1-phenyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid diethyl ester) synthesizedGlycosyl 1,4-dihydropyridine analogue (2,6-dimethyl-4-(3-O-benzyl-1,2-O-isopropylidene-beta-l-threo pentofuranos-4-yl)-1-phenyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid diethyl ester) synthesized in our laboratory, inhibited Leishmania donovani infection in vitro and in hamsters (Mesocricetus auratus) when administered orally. This analogue is nontoxic, cell-permeable and orally effective. This glycosyl dihydropyridine analogue functioned through arrest of cells in sub-G0/G1-phase, triggering mitochondrial membrane depolarization-mediated programmed cell death of the intracellular amastigotes.

• An orally effective dihydropyrimidone (DHPM) analogue induces apoptosis-like cell death in clinical isolates of Leishmania donovani overexpressing pteridine reductase 1.

  Authors: Neeloo Singh, Jaspreet Kaur, Pranav Kumar, Swati Gupta, Nasib Singh, Angana Ghosal, Avijit Dutta, Ashutosh Kumar, RamaPati Tripathi, Mohammad Siddiqi, Chitra Mandal, Anuradha Dube

  Parasitology research. 08/2009;

  The protozoan parasite Leishmania donovani is the causative agent of visceral leishmaniasis. The enzyme pteridine reductase 1 (PTR1) of L. donovani acts as a metabolic bypass for drugs targetingThe protozoan parasite Leishmania donovani is the causative agent of visceral leishmaniasis. The enzyme pteridine reductase 1 (PTR1) of L. donovani acts as a metabolic bypass for drugs targeting dihydrofolate reductase (DHFR); therefore, for successful antifolate chemotherapy to be developed against Leishmania, it must target both enzyme activities. Leishmania cells overexpressing PTR1 tagged at the N-terminal with green fluorescent protein were established to screen for proprietary dihydropyrimidone (DHPM) derivatives of DHFR specificity synthesised in our laboratory. A cell-permeable molecule with impressive antileishmanial in vitro and in vivo oral activity was identified. Structure activity relationship based on homology model drawn on our recombinant enzyme established the highly selective inhibition of the enzyme by this analogue. It was seen that the leishmanicidal effect of this analogue is triggered by programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide (PI), loss of mitochondrial membrane potential culminating in cell cycle arrest at the sub-G0/G1 phase and oligonucleosomal DNA fragmentation. Hence, this DHPM analogue [(4-fluoro-phenyl)-6-methyl-2-thioxo-1, 2, 3, 4-tetrahydropyrimidine-5-carboxylic acid ethyl ester] is a potent antileishmanial agent that merits further pharmacological investigation.

• Leishmania donovani: A glycosyl dihydropyridine analogue induces apoptosis like cell death via targeting pteridine reductase 1 in promastigotes.

  Authors: Jaspreet Kaur, Biswajit Kumar Singh, Rama Pati Tripathi, Prashant Singh, Neeloo Singh

  Experimental parasitology. 08/2009;

  Targeting of pteridine reductase1 (PTR1) in Leishmania is essential for development of successful antifolate chemotherapy. In search for specific inhibitors of PTR1 we have previously reported phenylTargeting of pteridine reductase1 (PTR1) in Leishmania is essential for development of successful antifolate chemotherapy. In search for specific inhibitors of PTR1 we have previously reported phenyl 1, 4-dihydropyridine ring as the lead structure showing antileishmanial efficacy in vitro and by the oral route in vivo. In this study we present programmed cell death inducing potential of this glycosyl dihydropyridine analogue (2, 6-dimethyl-4-(3-O-benzyl-1, 2-O-isopropylidene-beta-L-threo-pentofuranos-4-yl)-1-phenyl-1, 4-dihydro-pyridine-3, 5-dicarboxylic acid diethyl ester). Flow cytometric analysis revealed that this analogue induces cell cycle arrest at G2/M phase with subsequent increase in sub-G1 peak. Incubation of Leishmania promastigotes with this analogue causes exposure of phosphatidylserine to the outer leaflet of plasma membrane, formation of reactive oxygen species, depolarization of mitochondrial membrane potential and concomitant nuclear alterations that included DNA fragmentation. The results from this study on promastigotes give important lead to investigate further in intracellular amastigotes, the biologically relevant parasite stage in host macrophages.

• Leishmania donovani: A glycosyl dihydropyridine analogue induces apoptosis like cell death via targeting pteridine reductase 1 in promastigotes

  Authors: Jaspreet Kaur, Biswajit Kumar Singh, Rama Pati Tripathi, Prashant Singh, Neeloo Singh

  Experimental Parasitology.

  Targeting of pteridine reductase 1 (PTR1) in Leishmania is essential for development of successful antifolate chemotherapy. In search for specific inhibitors of PTR1 we have previously reportedTargeting of pteridine reductase 1 (PTR1) in Leishmania is essential for development of successful antifolate chemotherapy. In search for specific inhibitors of PTR1 we have previously reported phenyl 1,4-dihydropyridine ring as the lead structure showing antileishmanial efficacy in vitro and by the oral route in vivo. In this study, we present programmed cell death inducing potential of this glycosyl dihydropyridine analogue (2,6-dimethyl-4-(3-O-benzyl-1,2-O-isopropylidene-β-l-threo-pentofuranos-4-yl)-1-phenyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid diethyl ester). Flow cytometric analysis revealed that this analogue induces cell cycle arrest at G2/M phase with subsequent increase in sub-G1 peak. Incubation of Leishmania promastigotes with this analogue causes exposure of phosphatidylserine to the outer leaflet of plasma membrane, formation of reactive oxygen species, depolarization of mitochondrial membrane potential and concomitant nuclear alterations that included DNA fragmentation. The results from this study on promastigotes give important lead to investigate further in intracellular amastigotes, the biologically relevant parasite stage in host macrophages.

• Leishmania donovani: Oral therapy with glycosyl 1,4-dihydropyridine analogue showing apoptosis like phenotypes targeting pteridine reductase 1 in intracellular amastigotes

  Authors: Jaspreet Kaur, Nasib Singh, Biswajit Kumar Singh, Anuradha Dube, Rama Pati Tripathi, Prashant Singh, Neeloo Singh

  Experimental Parasitology.

  Glycosyl 1,4-dihydropyridine analogue (2,6-dimethyl-4-(3-O-benzyl-1,2-O-isopropylidene-β-l-threo pentofuranos-4-yl)-1-phenyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid diethyl ester) synthesized inGlycosyl 1,4-dihydropyridine analogue (2,6-dimethyl-4-(3-O-benzyl-1,2-O-isopropylidene-β-l-threo pentofuranos-4-yl)-1-phenyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid diethyl ester) synthesized in our laboratory, inhibited Leishmania donovani infection in vitro and in hamsters (Mesocricetus auratus) when administered orally. This analogue is nontoxic, cell-permeable and orally effective. This glycosyl dihydropyridine analogue functioned through arrest of cells in sub-G0/G1-phase, triggering mitochondrial membrane depolarization-mediated programmed cell death of the intracellular amastigotes.