Department Of Chemistry
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Item Structural, kinetic and thermodynamic characterizations of SDS-induced molten globule state of a highly negatively charged cytochrome c(Oxford University Press, 2019) Jain, R; Sharma, D; Kumar, Rakesh; Kumar, RajeshThis study presents the structural, kinetic and thermodynamic characterizations of previously unknown submicellar concentrations of SDS-induced molten globule (MGSDS) state of a highly negatively charged basedenatured ferricytochrome c (U B -state) at pH ∼12.8 (±0.2). The far-UV CD, near-UV CD, ANS-fluorescence data of UB-state in the presence of different concentrations of SDS indicate that the submicellar concentrations of SDS (≤0.4mM) transform the UBstate to MG SDS -state. The MG SDS -state has nativelike α-helical secondary structure but lacks tertiary structure. The free energy change (ΔG° D) for U B → MG SDS transition determined by far-UV CD (∼2.7 kcal mol -1 ) is slightly higher than those determined by fluorescence (∼2.0 kcal mol -1 ) at 25°C. At very low SDS and NaCl concentrations, the MG SDS -state undergoes cold denaturation. As SDS concentration is increased, the thermal denaturation temperature increases and the cold denaturation temperature decrease. Kinetic experiments involving the measurement of the CO-association rate to the base-denatured ferrocytochrome c at pH ≈12.8 (±0.2), 25°C indicate that the submicellar concentrations of SDS restrict the internal dynamics of base-denatured protein. © The Author(s) 2018. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.Item Chitosan-supported copper as an efficient and recyclable heterogeneous catalyst for A3/decarboxylative A3-coupling reaction(Elsevier Ltd, 2018) Kaur, Pavneet; Kumar, Bhupinder; Kumar, Vinod; Kumar, RakeshChitosan-supported copper (chit@copper) based heterogeneous catalysts have been explored for A3-coupling and decarboxylative A3-coupling. The developed protocol employs low catalyst loading, solventless condition and easy work-up for the synthesis of diversely substituted propargylamines. More importantly, the catalyst could be recovered and reused without any significant loss in the activity. This offer huge advantages as recyclability issues are rarely addressed in decarboxylative A3-coupling. Leaching studies were carried out using AAS and ICPMS analysis. It is envisaged that chit@copper catalysts can have potential applications in terms of efficiency and recyclability in the emerging area of decarboxylative C?H bond activation/functionalization strategies. ? 2018 Elsevier LtdItem Recent synthetic strategies for monocyclic azole nucleus and its role in drug discovery and development(Bentham Science Publishers B.V., 2018) Neha; Dwivedi, Ashish Ranjan; Kumar, Rakesh; Kumar, VinodBackground: In recent years, the development and diversification of heterocyclic compounds has become central to the discovery of bioactive compounds with novel or improved pharmacological properties. In particular, N-containing heterocycles are proved to be promising leads and drug candidates, and received huge attention of the medicinal chemists. Objective: Many drugs especially antibiotics are becoming obsolete due to the development of multidrug resistance. Moreover, toxicity and other side effects of some drugs necessitated the quest for safer and more potent drug candidates. The current review article described biological potential of various monocyclic azoles. Recent developments in the synthesis of azole derivatives have been also reviewed. Conclusion: The presence of N-heterocyclic rings can influence the pharmacokinetics, pharmacodynamics, pKa and bioavailability profile of the drug molecules. Compounds containing monocyclic azole rings showed various biological activities and number of molecules are in clinical practice. A number of important leads and potential drug candidates containing azole nucleus are in advance stages of drug developments. Thus, simple, atom economic and more efficient synthetic strategies are desired for the synthesis of new libraries of the compounds. ? 2018 Bentham Science Publishers.Item Heck−Suzuki Tandem Reaction for the Synthesis of 3‑Benzazepines(ACS Publications, 2015) Peshkov, Anatoly A.; Peshkov, Vsevolod A.; Pereshivko, Olga P.; Hecke, Kristof Van; Kumar, Rakesh; Eycken, Erik V. Van derA novel procedure for the Heck−Suzuki tandem reaction suitable for the construction of nitrogen-containing medium rings was developed to provide access toward the 3-benzazepine framework.Item Mechanisms of tubulin binding ligands to target cancer cells: Updates on their therapeutic potential and clinical trials(Bentham Science Publishers B.V., 2017) Kumar, Bhupinder; Kumar, Rakesh; Skvortsova, Ira; Kumar, VinodBackground: A number of chemically diverse substances bind to the tubulin and inhibit cell proliferation by disrupting microtubule dynamics. There are four binding sites for the ligands binding to the tubulin; taxane/epothilone and laulimalide/peloruside binding ligands stabilize microtubule while vinca and colchicine binding site agents promote microtubule depolymerization. Most of the tubulin binding ligands disturb the tubulin-microtubule dynamic equilibrium but these may exhibit anticancer activities through different mechanisms. Taxanes and epothilones are widely used cytotoxic agents and are found effective against different types of human malignancies. However, taxanes are susceptible to pgp mediated multi-drug resistance, dose limiting hematopoietic toxicity and cumulative neurotoxicity. Vinca alkaloids are already in clinical practice, but ligands binding to the colchicine site are still in the different stages of clinical trials. Objective: In the current review article, plausible mechanistic details about the interactions of ligands at the binding pocket and subsequent changes in the tubulin structure are described. The review article also illustrated different formulations of the tubulin binding agents in combination with other chemotherapeutic agents and their therapeutic potential against various human malignancies. Conclusion: Tubulin targeting agents emerged as one of the most successful anticancer drugs and a number of structurally different chemical compounds are in advance stages of clinical development. ? 2017 Bentham Science Publishers.