Browsing by Author "Satish Kumar Awasthi"

Now showing 1 - 7 of 7

Design, synthesis and biological evaluation of ciprofloxacin tethered bis-1,2,3-triazole conjugates as potent antibacterial agents
(Elsevier Masson SAS, 2016) Rama Kant; Vishal Singh; Gopal Nath; Satish Kumar Awasthi; Alka Agarwal
A series of new bis-1,2,3-triazole linked ciprofloxacin conjugates was designed, synthesized and evaluated in vitro antibacterial activity against a panel of clinically relevant bacteria. A significant part of the compounds displayed enhanced activity against both Gram-positive and Gram-negative species of bacteria as compared to the parent drug. Additionally, negligible toxicity profile of compounds indicates that they may act a good antibiotic in future. Despite relatively small number of synthesized conjugates, it was possible to observe important dependences between their structure and activity. © 2016 Elsevier Masson SAS
Hydrogen bonding patterns and DFT studies of (4-Acetylphenyl)amino 2,2-Dimethylpropanoate and (E)-1-(4-aminophenyl)-3-[4-(dimethylamino)phenyl] prop-2-en-1-one
(Springer New York LLC, 2014) Rama Kant; Biswajit Maiti; Satish Kumar Awasthi; Alka Agarwal
The (4-acetylphenyl)amino 2,2-dimethylpropanoate (1) and (E)-1-(4-aminophenyl)-3-[4-(dimethylamino)phenyl]prop-2-en-1-one (2), were synthesized and characterized by elemental analysis, FT-IR, 1H NMR, 13CNMR and single crystal X-ray diffraction techniques. Both compounds 1 and 2 crystallized in orthorhombic crystal system with Pbca and P212121 space group respectively, having the unit cell parameters: a = 11.7220(12) Å, b = 14.4580(13) Å, c = 15.7853(12) Å, β = 90°, Volume = 2675.2(4) Å3, Z = 8 for 1 and a = 6.1146(5) Å, b = 9.0567(8) Å, c = 26.079(3) Å, β = 90°, Volume = 1444.2(2) Å3, Z = 4 for compound 2. The crystal structures of both compounds (1 and 2) are stabilized by N-H···O strong intermolecular hydrogen bonding forming C 1 1 (8) motifs. In compound 1, the molecules are linked by three C-H···O intramolecular H-bond forming S(6) motifs. In compound 2, the molecules are linked by C-H···N intermolecular H-bond exhibiting C 1 1 (12) motif and C-H···O intramolecular H-bond leading to S(5) motif. Crystallographic and vibrational data are compared with the results of density functional theory (DFT) method at the B3LYP/6-31G(d,p) level. The electronic (UV-vis) spectra was calculated by using the TD-DFT method and correlated with experimental spectra. © 2014 Springer Science+Business Media New York.
Inherent Flexibility vis-à-vis Structural Rigidity in Chemically Stable Antimalarial Dispiro N-Sulfonylpiperidine Tetraoxanes
(Wiley-Blackwell, 2018) Chiranjeev Sharma; Kumkum Sharma; Jitendra Kumar Yadav; Alka Agarwal; Satish Kumar Awasthi
Structurally diverse and chemically stable tetraoxanes were formed by peroxidation of N-sulfonylpiperidones. X-ray analysis revealed that the crystal structures possess central spiro-2,5-disubstituted tetraoxane rings trans fused to 6-membered piperidine and cyclohexylidene substituents in classical chair conformations. The more flexible cycloheptane ring exhibited pseudorotation between chair and twist chair conformation. The two sulfonyl oxygen atoms act as hydrogen-bonding acceptors and participate in hydrogen bonding. Docking calculations showed that the tetraoxanes are aligned parallel to the plane of the porphyrin ring of heme so that the iron can attack the O−O bond to initiate redox-mediated reaction to render nanomolar antimalarial potency to these compounds against P. falciparum 3D7. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Insight into the interaction of benzothiazole tethered triazole analogues with human serum albumin: Spectroscopy and molecular docking approaches
(John Wiley and Sons Ltd, 2019) Priyanka Yadav; Jitendra Kumar Yadav; Arvind Kumar Dixit; Alka Agarwal; Satish Kumar Awasthi
The interaction of four benzothiazole tethered triazole analogues (MS43, MS70, MS71, and MS78) with human serum albumin (HSA) was investigated using various spectroscopic techniques (ultraviolet–visible (UV–vis) light absorption, fluorescence, circular dichroism (CD), molecular docking and density functional theory (DFT) studies). Fluorescence quenching constants (~1012) revealed a static mode of quenching and binding constants (Kb ~104) indicating the strong affinity of these analogues for HSA. Further alteration in the secondary structure of HSA in the presence of these analogues was also confirmed by far UV–CD spectroscopy. The intensity loss in CD studied at 222 nm indicated an increase in random coil/β-sheet conformations in the protein. Binding energy values (MS71 (−9.3 kcal mol−1), MS78 (−8.02 kcal mol−1), MS70 (−7.16 kcal mol−1) and MS43 (−6.81 kcal mol−1)) obtained from molecular docking revealed binding of these analogues with HSA. Molecular docking and DFT studies validated the experimental results, as these four analogues bind with HSA at site II through hydrogen bonding and hydrophobic interactions. © 2019 John Wiley & Sons, Ltd.
Is structural hybridization invoking new dimensions for antimalarial drug discovery research?
(Royal Society of Chemistry, 2023) Bhawana Sharma; Alka Agarwal; Satish Kumar Awasthi
Despite effective prevention methods, malaria is a devastating, persistent infection caused by protozoal parasites that result in nearly half a million fatalities annually. Any progress made thus far in the eradication of the disease is jeopardized by the expansion of malaria parasites that have evolved to become resistant to a wide range of drugs, including first-line therapy. To surmount this significant obstacle, it is necessary to develop newly synthesized drugs with multiple modes of action that may have a novel target in various stages of Plasmodium parasite development and this is made possible by the hybridization concept. Hybridization is the combination of at least two diverse pharmacophore units with some linkers bringing about a single molecule with a diverse mode of action. It intensifies a drug's physiological and chemical characteristics, such as absorption, cellular target contact, metabolism, excretion, distribution, and toxicity. This review article outlines the currently published most potent hybrid drugs against the Plasmodium species. © 2023 RSC.
Synthesis of newer 1,2,3-triazole linked chalcone and flavone hybrid compounds and evaluation of their antimicrobial and cytotoxic activities
(Elsevier Masson SAS, 2016) Rama Kant; Dharmendra Kumar; Drishti Agarwal; Rinkoo Devi Gupta; Ragini Tilak; Satish Kumar Awasthi; Alka Agarwal
The present study was carried out in an attempt to synthesize a new class of antimicrobial and antiplasmodial agents by copper catalyzed click chemistry to afford 25 compounds 10-14(a-e) of 1,4-disubstituted-1,2,3-triazole derivatives of chalcones and flavones. The structures of the newly synthesized compounds were established by elemental analysis, IR, 1H NMR, 13C NMR and Mass spectral data. The newly synthesized compounds were evaluated for their antibacterial activity against Gram positive bacteria (Staphylococcus aureus, Enterococcus faecalis), Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella boydii, Klebsiella pneumoniae) and antifungal activity against (Candida albicans, Candida tropicalis, Candida parapsilosis, Cryptococcus neoformans, Dermatophyte) as well as molds (Aspergillus niger, Aspergillus fumigatus). The antiplasmodial and cytotoxic activities of these compounds were also evaluated against human malaria parasite Plasmodium falciparum strain 3D7 and human hepato-cellular carcinoma cells (Huh-7), respectively. Compounds 10a, 10c, 10d, 12c and 14e showed promising antibacterial activity while compounds 10e, 11d, 11e, 12c, 13a, 13b, 13e, 14a and 14d showed good antifungal activity as compared to the corresponding standard drugs. Compound 10b was found to be the most active against Plasmodium falciparum while the remaining compounds showed moderate to weak antiplasmodial activity. However, cytotoxic activities of all compounds were found ineffective against Huh-7 cells. © 2016 Elsevier Masson SAS. All rights reserved.
Synthetic application of gold nanoparticles and auric chloride for the synthesis of 5-substituted 1H-tetrazoles
(Royal Society of Chemistry, 2015) Satyanand Kumar; Arvind Kumar; Alka Agarwal; Satish Kumar Awasthi
An effective one-pot, convenient gold catalyzed synthesis of 5-substituted 1H-tetrazoles has been discussed. The study demonstrated the comparative overview for utilization of gold(iii) and gold nano-particles (spheres) as a catalyst. Detailed understandings of the mechanism, surface area effect (in reference to nanoparticles) of gold in the activation of nitriles for nucleophilic (3 + 2) cycloaddition of sodium azide to give the product have also been studied. This journal is © The Royal Society of Chemistry.