Browsing by Author "Abdur Rub"

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Identification of novel inhibitors against UDP-galactopyranose mutase to combat leishmaniasis
(Wiley-Liss Inc., 2018) Mohammad Kashif; Shams Tabrez; Atahar Husein; Mohd Arish; Ponnusamy Kalaiarasan; Partha P. Manna; Naidu Subbarao; Yusuf Akhter; Abdur Rub
Leishmania, a protozoan parasite that causes leishmaniasis, affects 1-2 million people every year worldwide. Leishmaniasis is a vector born disease and characterized by a diverse group of clinical syndromes. Current treatment is limited because of drug resistance, high cost, poor safety, and low efficacy. The urgent need for potent agents against Leishmania has led to significant advances in the development of novel antileishmanial drugs. β-galactofuranose (β-Galf) is an important component of Leishmanial cell surface matrix and plays a critical role in the pathogenesis of parasite. UDP-galactopyranose mutase (UGM) converts UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf) which acts as the precursor for β-Galf synthesis. Due to its absence in human, this enzyme is selected as the potential target in search of new antileishmanial drugs. Three dimensional protein structure model of Leishmania major UGM (LmUGM) has been homology modeled using Trypanosoma cruzi UGM (TcUGM) as a template. The stereochemistry was validated further. We selected already reported active compounds from PubChem database to target the LmUGM. Three compounds (6064500, 44570814, and 6158954) among the top hit occupied the UDP binding site of UGM suggested to work as a possible inhibitor for it. In vitro antileishmanial activity assay was performed with the top ranked inhibitor, 6064500. The 6064500 molecule has inhibited the growth of Leishmania donovani promastigotes significantly. Further, at similar concentrations it has exhibited significantly lesser toxicity than standard drug miltefosine hydrate in mammalian cells. © 2017 Wiley Periodicals, Inc.
In silico studies and evaluation of antiparasitic role of a novel pyruvate phosphate dikinase inhibitor in Leishmania donovani infected macrophages
(Elsevier B.V., 2019) Mohammad Kashif; Sumit Kumar Hira; Anurag Upadhyaya; Uttam Gupta; Ranjeet Singh; Ankush Paladhi; Faez Iqbal Khan; Abdur Rub; Partha Pratim Manna
The present work deals with the identification and characterization of a novel inhibitor Z220582104, specific to pyruvate phosphate dikinase, for leishmanicidal activities against free promastigotes and intracellular amastigotes. We have used structure-based drug designing approaches and performed homology modelling, virtual screening and molecular dynamics studies. Primary mouse macrophages and macrophage cell line J774A1 were infected with promastigotes of Leishmania donovani. Both promastigotes and infected macrophages were subjected to treatment with the varying concentrations of Z220582104 or miltefosine for assessment of leishmanicidal activity. The novel inhibitor Z220582104 demonstrated growth inhibitory potential and reduced the viability of the free promastigotes in a concentration- and time-dependent manner. Z220582104 was also effective against the intracellular form of the parasites and reduced the number of amastigotes in macrophages and also lowered the parasite index, compared with the untreated infected macrophages. Although less effective compared with the miltefosine, Z220582104 is well tolerated by the dividing cells and normal human lymphocytes and monocytes with no adverse effects on the growth kinetics or viability. Our in silico and in vitro studies suggested that Leishmania donovani pyruvate phosphate dikinase could be a potential new drug target. © 2018 Elsevier B.V. and International Society of Chemotherapy
Screening of novel inhibitors against Leishmania donovani calcium ion channel to fight leishmaniasis
(Bentham Science Publishers B.V., 2017) Mohammad Kashif; Partha P. Manna; Yusuf Akhter; Mohammed Alaidarous; Abdur Rub
Leishmania is an intracellular protozoan parasite which causes Leishmaniasis, a global health problem affecting millions of people throughout 89 different countries in the world. The current treatment which includes use of amphotericin B, antimonials, and others has major drawbacks due to toxicity, resistance, and extraordinary high cost. So there is an urgent need of development of new drug targets to fight against leishmaniasis. In this regard we have selected Leishmania donovani Ca2+ ion channel (Ld-CC) as potential drug target. Ld-CC regulates concentration of Ca2+ ions which is involved in several functions like flagellar motion, mitochondrial oxidative metabolism and entry inside the macrophages. Since Ld-CC has not been characterised yet, we performed homology modelling of Leishmania donovani Ca2+ ion channel (Ld-CC) and docking studies of ligand library against this channel. 542 compound library of National Cancer Institute (NCI) diversity 3 dataset selected for screening studies. The ligands ZINC17287336 and ZINC29590262 were selected as best energy conformers because they show highest binding affinity towards its target (Ld-CC). They interact with the active site residues in the pocket of Ld-CC which suggests that the docked conformations are good and acceptable. Moreover, these two selected compounds also have relatively high binding affinity than nifedipine and verapamil, known human calcium channel blockers which had been reported to have mild anti-leishmanial activity. Among these two top screened inhibitors the ligand ZINC29590262 shows poor binding affinity towards the Human voltage-dependent L-type calcium channel subunit alpha-1C in comparison to the Ld-CC. Therefore, we proposed this ligand as the best inhibitor which shows 40% more binding affinity with Ld-CC than the human-VDCC. These results suggest that our screened ligand ZINC29590262 could act as novel drug and may show much better antileishmanial activity. © 2017 Bentham Science Publishers.
Synthesis, Biological Evaluation, Molecular Docking and DFT Study of Potent Antileishmanial Agents Based on the Thiazolo[3, 2-a]pyrimidine Chemical Scaffold
(Wiley-Blackwell, 2018) Radha N. Chaturvedi; Mohd Arish; Mohammad Kashif; Varinder Kumar; Reenu; Krishnaiah Pendem; Abdur Rub; Sunita Malhotra
A series of 20 compounds having thiazolo[3, 2-a]pyrimidine chemical scaffold were synthesized and evaluated for their antileishmanial activity against promastigotes of Leishmania donovani. Amongst all, two compounds showed promising antileishmanial activity in comparison to other compounds. Inhibitory concentration 50% (IC50) was calculated as 42.1 μM and 25.1 μM with selectivity index of 8.3 and 6.05, respectively against Miltefosine (reference drug) 37.78 μM with selectivity index of 2.05. To confirm the target of the these molecules, we modelled Leishmania donovani Ca2+ ion channel (LdCC) protein and performed the docking analysis of the best antileishmanial activity exhibiting inhibitors. The free energy of binding was observed as −10.2 and −9.6 kcal mol−1 in comparison to reference drug −6.2 kcal mol−1. It also makes several hydrogen bonds with our conserved residue Ser1655, Tyr1598 and Asn927. Furthermore, several hydrophobic contacts were also observed within the pocket. Finally, computational work employing density functional theory (DFT) was also carried out to investigate the electronic properties of the synthesized compounds. The in vitro and in silico activities conclusively revealed that our lead compounds may be used as a novel therapeutics against leishmaniasis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim