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253 results on '"Biswal, Himansu S."'

2. In silico identification of potential natural product inhibitors of human proteases key to SARS-CoV-2 infection

Author

Vivek-Ananth, R. P., Rana, Abhijit, Rajan, Nithin, Biswal, Himansu S., and Samal, Areejit

Subjects
Quantitative Biology - Biomolecules, Quantitative Biology - Molecular Networks
Abstract

Presently, there are no approved drugs or vaccines to treat COVID-19 which has spread to over 200 countries and is responsible for over 3,65,000 deaths worldwide. Recent studies have shown that two human proteases, TMPRSS2 and cathepsin L, play a key role in host cell entry of SARS-CoV-2. Importantly, inhibitors of these proteases were shown to block SARS-CoV-2 infection. Here, we perform virtual screening of 14010 phytochemicals produced by Indian medicinal plants to identify natural product inhibitors of TMPRSS2 and cathepsin L. We built a homology model of TMPRSS2 as an experimentally determined structure is not available. AutoDock Vina was used to perform molecular docking of phytochemicals against TMPRSS2 model structure and cathepsin L crystal structure. Potential phytochemical inhibitors were filtered by comparing their docked binding energies with those of known inhibitors of TMPRSS2 and cathepsin L. Further, the ligand binding site residues and non-covalent protein-ligand interactions were used as an additional filter to identify phytochemical inhibitors that either bind to or form interactions with residues important for the specificity of the target proteases. We have identified 96 inhibitors of TMPRSS2 and 9 inhibitors of cathepsin L among phytochemicals of Indian medicinal plants. The top inhibitors of TMPRSS2 are Edgeworoside C, Adlumidine and Qingdainone, and of cathepsin L is Ararobinol. Interestingly, several herbal sources of identified phytochemical inhibitors have antiviral or anti-inflammatory use in traditional medicine. Further in vitro and in vivo testing is needed before clinical trials of the promising phytochemical inhibitors identified here., Comment: 51 pages, 7 Figures, 2 Tables, 4 SI Figures, SI Tables available upon request from authors

Published
2020
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4. Manganese matere bonds in biological systems: PDB inspection and DFT calculations.

Author

Burguera, Sergi, Sahu, Akshay Kumar, Chávez Romero, Michael Jordan, Biswal, Himansu S., and Bauzá, Antonio

Abstract

A Protein Data Bank (PDB) survey has revealed noncovalent contacts involving Mn centres and protein residues. Their geometrical features are in line with the interaction between low electron density sites located along the Mn–O/N coordination bonds (σ-holes) and the lone pairs belonging to TYR, SER or HIS residues, known as a matere bond (MaB). Calculations at the PBE0-D3/def2-TZVP level of theory were used to investigate the strength and shed light on the physical nature of the interaction. We expect the results presented herein will be useful for those scientists working in the fields of bioinorganic chemistry, particulary in protein–metal docking, by providing new insights into transition metal⋯Lewis base interactions as well as a retrospective point of view to further understand the structural and functional implications of this key transition metal ion. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Thio and Seleno‐Psoralens as Efficient Triplet Harvesting Photosensitizers for Photodynamic Therapy.

Author

Jena, Subhrakant, Mohanty, Pranay, Rout Rout, Saiprakash, Kumar Pati, Saswat, and Biswal, Himansu S.

Subjects
PHOTODYNAMIC therapy, PHOTOSENSITIZERS, SPIN-orbit interactions, OSCILLATOR strengths, BAND gaps
Abstract

The Psoralen (Pso) molecule finds extensive applications in photo‐chemotherapy, courtesy of its triplet state forming ability. Sulfur and selenium replacement of exocyclic carbonyl oxygen of organic chromophores foster efficient triplet harvesting with near unity triplet quantum yield. These triplet‐forming photosensitizers are useful in Photodynamic Therapy (PDT) applications for selective apoptosis of cancer cells. In this work, we have critically assessed the effect of the sulfur and selenium substitution at the exocyclic carbonyl (TPso and SePso, respectively) and endocyclic oxygen positions of Psoralen. It resulted in a significant redshifted absorption spectrum to access the PDT therapeutic window with increased oscillator strength. The reduction in singlet‐triplet energy gap and enhancement in the spin‐orbit coupling values increase the number of intersystem crossing (ISC) pathways to the triplet manifold, which shortens the ISC lifetime from 10−5 s for Pso to 10−8 s for TPso and 10−9 s for SePso. The intramolecular photo‐induced electron transfer process, a competitive pathway to ISC, is also considerably curbed by exocyclic functionalizations. In addition, a maximum of 115 GM of two‐photon absorption (2PA) with IR absorption (660–1050 nm) confirms that the Psoralen skeleton can be effectively tweaked via single chalcogen atom replacement to design a suitable PDT photosensitizer. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Adduct-based p-doping of organic semiconductors

Author

Sakai, Nobuya, Warren, Ross, Zhang, Fengyu, Nayak, Simantini, Liu, Junliang, Kesava, Sameer V., Lin, Yen-Hung, Biswal, Himansu S., Lin, Xin, Grovenor, Chris, Malinauskas, Tadas, Basu, Aniruddha, Anthopoulos, Thomas D., Getautis, Vytautas, Kahn, Antoine, Riede, Moritz, Nayak, Pabitra K., and Snaith, Henry J.

Published
2021
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22. Tetrel bonds involving a CF3 group participate in protein–drug recognition: a combined crystallographic and computational study.

Author

Piña, María de las Nieves, Sahu, Akshay Kumar, Frontera, Antonio, Biswal, Himansu S., and Bauzá, Antonio

Abstract

In this study, the ability of CF3 groups to bind to the electron-rich side chains and backbone groups of proteins has been investigated by combining a Protein Data Bank (PDB) survey and ab initio quantum mechanics calculations. More precisely, an inspection of the PDB involving organic ligands containing a CF3 group and electron-rich atoms (A = N, O and S) in the vicinity revealed 419 X-ray structures exhibiting CF3⋯A tetrel bonds (TtBs). In a posterior stage, those hits that exhibited the most relevant features in terms of directionality and intermolecular distance were selected for theoretical calculations at the RI-MP2/def2-TZVPD level of theory. Also, Hammett's regression plots of several TtB complexes involving meta- and para-substituted benzene derivatives were computed to shed light on the substituent effects. Moreover, the TtBs were characterized through several state-of-the-art computational techniques, such as the Quantum Theory of Atoms in Molecules (QTAIM) and Noncovalent Interactions plot (NCIplot) methodologies. We believe that the results gathered from our study will be useful for rational drug design and biological communities as well as for further expanding the role of this interaction to biomedical applications. [ABSTRACT FROM AUTHOR]

Published
2023
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32. Hydrogen Bonding Directed Reversal of 13C NMR Chemical Shielding.

Author

Jena, Subhrakant, Routray, Chinmay, Dutta, Juhi, and Biswal, Himansu S.

Subjects
HYDROGEN bonding, THIOAMIDES, SELENIUM, NUCLEAR magnetic resonance spectroscopy, AMIDES, SULFUR
Abstract

The deshielding or downfield 13C NMR chemical shift of amide carbonyl carbon upon H‐bonding is a widely observed phenomenon. This downfield shift is commonly used as a spectroscopic ruler for H‐bonding. However, the very first observation of an upfield 13C NMR of thiocarbonyl carbon in thioamides upon H‐bonding encouraged us to explore the physical origin of the reversal of 13C NMR chemical shielding. Careful NMR analysis shows that sulfur and selenium‐centered H‐bonds (S/SeCHBs) induce a shielding effect on the 13CC=S(Se) while changing from amides to thioamides or selenoamides. In addition, natural chemical shielding (NCS) analysis shows that the σ11 and σ22 components of the isotropic shielding tensor (σ) have a crucial role in this unusual shielding. [ABSTRACT FROM AUTHOR]

Published
2022
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37. The Redox-Active Conopeptide Derived from the Venom Duct Transcriptome of Conus lividus Assists in the Oxidative Folding of Conotoxin

Author

Dolle, Ashwini, primary, Vijayasarathy, Marimuthu, additional, Shekh, Shamasoddin, additional, Hunashal, Yamanappa, additional, Reddy, K. Kasi Amarnath, additional, Prakash, Sunita, additional, Rana, Abhijit, additional, Biswal, Himansu S., additional, Raghothama, Srinivasarao, additional, and Gowd, Konkallu Hanumae, additional

Published
2021
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45. Characterization of (Boc‐Cys/Sec‐NHMe) 2 and (Boc‐Cys/Sec‐OMe) 2 : Evidence of local conformational difference between disulfide and diselenide

Author

Dolle, Ashwini, primary, Reddy, K. Kasi Amarnath, additional, Gunaga, Shubha Shridhar, additional, Krishnamurthy, Kiran, additional, Senapati, Dillip Kumar, additional, Rana, Abhijit, additional, Sindogi, Kishorkumar, additional, Biswal, Himansu S., additional, Raghothama, Srinivasarao, additional, and Gowd, Konkallu Hanumae, additional

Published
2020
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