Browsing by Author "Poornima Sharma"

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A novel Raman spectroscopic approach to identify polymorphism in leflunomide: A combined experimental and theoretical study
(John Wiley and Sons Ltd, 2016) Poornima Sharma; Debraj Gangopadhyay; Sima Umrao; Shiv Kumar; A.K. Ghosh; P.C. Mishra; Ranjan K. Singh
Polymorphism is an important characteristic which affects the activity, solubility and other physical properties of a compound and can be induced by varying temperature, pressure and solvent. The presence and conversion of α to β polymorphic forms of an anti-rheumatic drug leflunomide have been studied by temperature-dependent and in situ Raman observations. Both α and β polymorphs were found to co-exist in the temperature interval 367-372 K. The α form alone exists below 367 K and the β form alone above 373 K. The C=O stretching band clearly demonstrates the α → β conversion because of breaking of N-H···O bond and formation of N-H···N bond. On cooling the Raman spectra suggest the irreversibility of this conversion. Thermodynamic stability, crystal parameters and surface morphology of both forms in the leflunomide powder used for the present study have been verified by differential scanning calorimetry, X-ray powder diffraction and scanning electron microscopy. © 2015 John Wiley & Sons, Ltd.
Detection of in Vitro Metabolite Formation of Leflunomide: A Fluorescence Dynamics and Electronic Structure Study
(American Chemical Society, 2016) Poornima Sharma; Debraj Gangopadhyay; Phool Chand Mishra; Hirdyesh Mishra; Ranjan K. Singh
The metabolic transformation of antirheumatic fluorescent drug leflunomide into its active metabolite teriflunomide through isoxazole ring opening has been monitored in vitro using steady state and time domain fluorescence spectroscopy and density functional theory. During metabolic reaction, absorption of leflunomide split into two bands resembling absorption spectra of teriflunomide. The fluorescence spectra reveal slow conversion of leflunomide to E and Z forms of teriflunomide in aqueous medium, which becomes faster at basic pH. The E form, which is more potent as a drug, becomes more stable with an increase in the basicity of the medium. Both molecules are associated with charge transfer due to twisting in the lowest singlet excited state. Excited state charge transfer followed by proton transfer was also observed in the Z form during the ring opening of leflunomide. Quantum yield and radiative decay rates have been observed to decrease for the metabolite because of an increase in nonradiative decay channels. © 2016 American Chemical Society.
Fermented papaya preparation modulates the progression of N-methyl-N-nitrosourea induced hepatocellular carcinoma in Balb/c mice
(Elsevier Inc., 2016) Jhoti Somanah; Srishti Ramsaha; Shalini Verma; Ashok Kumar; Poornima Sharma; Ranjan Kumar Singh; Okezie I. Aruoma; Emmanuel Bourdon; Theeshan Bahorun
Aim and main method The medicinal properties of fermented papaya preparation (FPP) derived from Carica papaya fruit was investigated in order to determine its ability to modulate the progression of N-methyl-N-nitrosourea induced hepatocellular carcinoma in Balb/c mice. Key findings As well as reducing the physical symptoms associated with N-methyl-N-nitrosourea (MNU)-induced hepatocellular carcinoma, supplementation of Balb/c mice with 500 mg FPP/kg BW for 92 days normalized the blood cell count, led to an increased activity of several key antioxidant enzymes (SOD: + 20%, CAT: + 81%, GPx: + 66.1%, GR: + 54.4%; P < 0.001 vs. MNU control), increased the ferrous reducing antioxidant potential (+ 36.7%, P < 0.001 vs. MNU control) and reduced the extent of lipid peroxidation in the liver by 44.3% (P < 0.001 vs. MNU control). Significance Results demonstrated the ability of FPP to preserve the integrity of liver against oxidative damage and protect hepatocytes against irreversible DNA structural modifications induced by MNU, highlighting its potential role as an immune-defense modulator during hepatocarcinoma. © 2016 Elsevier Inc.
In vitro concentration dependent detection of creatinine: a surface enhanced Raman scattering and fluorescence study
(Royal Society of Chemistry, 2016) Debraj Gangopadhyay; Poornima Sharma; Rajib Nandi; Moumita Das; Surajit Ghosh; Ranjan K. Singh
An attempt has been made to detect the concentration of creatinine in a very dilute aqueous solution in vitro on the basis of the Jaffe reaction, the commonly used reaction for clinical determination of creatinine concentration in blood serum or urine. For this various spectroscopic techniques viz. Raman spectroscopy, surface enhanced Raman scattering, UV-visible and fluorescence spectroscopy have been used. As a result of the Jaffe reaction using aqueous solutions of creatinine at different concentrations and picric acid and NaOH as reagents, a reddish orange colored Jaffe complex is produced. The concentration dependent SERS spectra of the Jaffe complex show gradual decrease in the intensity of ring deformation mode of creatinine on decreasing creatinine concentration. The concentration dependent absorption spectra of the Jaffe complex show changes in intensity in one of the absorption peaks characteristic of creatinine. The concentration dependent fluorescence emission spectra of the Jaffe complex show a blue shift in emission maxima on reducing the concentration of creatinine in the solution. The observed results suggest the possibility to detect the concentration of creatinine in a very dilute solution in vitro by SERS and fluorescence techniques and the application of these techniques in vivo might aid in a more specific and accurate determination of creatinine in serum or urine. © The Royal Society of Chemistry.
In vitro monitoring of ring opening of leflunomide: A surface enhanced Raman scattering and DFT based approach
(Elsevier, 2014) Poornima Sharma; Debraj Gangopadhyay; Pushkar Singh; P.C. Mishra; Volker Deckert; Jürgen Popp; Ranjan K. Singh
The in vitro mechanism of ring opening of leflunomide resulting in the formation of a metabolite A771726 has been studied by time series surface enhanced Raman spectra using NaOH buffer at pH ∼10. The decomposition of leflunomide into A771726 through NO bond cleavage was identified by the Raman signature of CN bond of A771726. The experimental results have been correlated with theory by transition state calculations of the reaction using different basic catalysts; OH-, formate and formate + water and water alone. The reaction barrier energy is found to be lowest with OH-as a catalyst. © 2014 Elsevier B.V. All rights reserved.
Modulation of hepatocarcinogenesis in N-methyl-N-nitrosourea treated Balb/c mice by mushroom extracts
(Royal Society of Chemistry, 2016) Srishti Ramsaha; Vidushi S. Neergheen-Bhujun; Shalini Verma; Ashok Kumar; Rahul Kumar Bharty; Amit Kumar Chaudhary; Poornima Sharma; Ranjan Kumar Singh; Priya Huzar Futty Beejan; Kang Kyung-Sun; Theeshan Bahorun
The hepatoprotective potential of edible mushrooms from Mauritius, namely Pleurotus sajor-caju and Agaricus bisporus was evaluated using an N-methyl-N-nitrosourea (MNU)-induced hepatocarcinogenesis Balb/c mice model. Mushroom extracts restored normal weight in MNU treated mice over a 3 month supplementation period. Blood parameter analyses indicated a clear modulation of hemoglobin concentration, leukocyte, platelet, lymphocyte, neutrophil, monocyte and eosinophil counts in MNU-induced mice (p < 0.05). Mushroom extract supplementation effectively reduced oxidative damage in MNU-primed mice, which was marked by a significant decrease in the extent of lipid peroxidation (p < 0.05) and a concomitant increase in the enzymatic antioxidant levels, primarily catalase, superoxide dismutase, glutathione reductase and peroxidase, and FRAP values (p < 0.05). DNA protective effects of the extracts were confirmed by Raman spectroscopy, where, the MNU-DNA interaction, as evidenced by an intense peak at 1254 cm-1, was normalized. The findings demonstrate hepatoprotective, immunomodulatory and anti-carcinogenic effects and suggest the use of mushrooms as potential dietary prophylactics in cancer chemoprevention. © The Royal Society of Chemistry 2016.
Monitoring the in Vitro Thiazolidine Ring Formation of Antioxidant Drug N-Acetyl- l -cysteine at Basic pH and Detection of Reaction Intermediates: A Raman Spectroscopic and Ab Initio Study
(American Chemical Society, 2018) Debraj Gangopadhyay; Moumita Das; Keshav Kumar Singh; Poornima Sharma; Ranjan K. Singh; Poonam Tandon
The important cyclization reaction of antioxidant drug N-acetyl-l-cysteine (NAC) has been monitored in vitro at basic pH with the help of time series Raman spectroscopy. The thiazoline ring formation of NAC at acidic pH is a well-known reaction and has been studied extensively. However, the formation of a thiazolidine ring from NAC at basic pH has not been investigated precisely till date. The effect of basicity of the medium on the rate of cyclization has been investigated by studying the reaction at five different basic pH values. Raman signatures of cyclization have been observed with the passage of time and are found to appear faster as the basicity of the medium increases. Ab initio calculations have been done to understand the plausible mechanism of the reaction at basic pH. It is observed that formation of a thiazolidine ring from NAC occurs primarily in four steps, which involve proton abstraction from the thiol (SH) group of NAC and subsequent formation of an S-C bond by a nucleophilic attack of the C-S group on the protonated C-O-H group in NAC. Correlation of the theoretically calculated results with experimental Raman spectral analysis has led to a detailed and proper understanding of this important biochemical reaction. © Copyright 2018 American Chemical Society.
Multi-layered graphene quantum dots derived photodegradation mechanism of methylene blue
(Royal Society of Chemistry, 2015) Sima Umrao; Poornima Sharma; Anushka Bansal; Ranjna Sinha; Ranjan K. Singh; Anchal Srivastava
The photocatalytic degradation of methylene blue (MB) under visible light in the presence of a multi-layered graphene quantum dots (MLGQDs) photocatalyst has been investigated in aqueous heterogeneous solution. The photodegradation mechanism, following pseudo first order kinetics, was examined for the effects of the existing monomer (MB+)-dimer {(MB+)2} equilibrium in MB solution. The photocatalytic degradation efficiency of MB+ achieved 93.3% with a rate constant (k) of 0.056 min-1 after 60 min irradiation with green light, while less degradation ∼ 89.44% with k ∼ 0.024 min-1, was achieved for (MB+)2. MB+ is perhaps a short-lived species and favors the photodegradation of MB in comparison to the (MB+)2 species. Similar trends have been found under blue light irradiation. MB+ species easily pulls a proton from the functional groups of MLGQDs, resulting in an intermediate product Luco-methylene blue (LMB). Finally, all MB species and intermediate products degrade into an environmental benign product via highly reactive OH radicals. In addition, our ab initio theoretical results reveals that monomers abstract a proton from hydroxyl groups of MLGQDs and formation of LMB takes place, which is weakly bonded with MLGQDs by hydrogen bonds. © The Royal Society of Chemistry.
Raman signatures of strong and weak hydrogen bonds in binary mixtures of phenol with acetonitrile, benzene and orthodichlorobenzene
(John Wiley and Sons Ltd, 2016) Anurag Singh; Debraj Gangopadhyay; Rajib Nandi; Poornima Sharma; Ranjan K. Singh
The present study aims at investigating the effect of hydrogen bonds of phenol in binary mixtures of phenol with three solvents viz. acetonitrile, orthodichlorobenzene and benzene respectively in order of decreasing hydrogen bond strength. Raman spectroscopy in correlation with density functional theory (DFT) calculations has led to a profound understanding of changes in structure, energy, dipole moment and other physical and chemical properties of phenol pertaining to hydrogen bond formation in solution. The spectral variation in wavenumber and linewidth of ring deformation, ring stretching, C≡N stretching and C―H stretching modes have been analyzed in detail. The breaking of self association of phenol in solution and formation of strong or weak hydrogen bonds depending on the nature of the solvent has been discussed by comparing the Raman and DFT results for three different solvents. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Raman spectroscopic approach to monitor the in vitro cyclization of creatine → creatinine
(Elsevier, 2015) Debraj Gangopadhyay; Poornima Sharma; Sachin Kumar Singh; Pushkar Singh; Nicolae Tarcea; Volker Deckert; Jürgen Popp; Ranjan K. Singh
The creatine → creatinine cyclization, an important metabolic phenomenon has been initiated in vitro at acidic pH and studied through Raman spectroscopic and DFT approach. The equilibrium composition of neutral, zwitterionic and protonated microspecies of creatine has been monitored with time as the reaction proceeds. Time series Raman spectra show clear signature of creatinine formation at pH 3 after ∼240 min at room temperature and reaction is faster at higher temperature. The spectra at pH 1 and pH 5 do not show such signature up to 270 min implying faster reaction rate at pH 3. © 2014, Elsevier B.V. All rights reserved.
Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea
(Elsevier, 2016) Debraj Gangopadhyay; Sachin Kumar Singh; Poornima Sharma; Hirdyesh Mishra; V.K. Unnikrishnan; Bachcha Singh; Ranjan K. Singh
Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations. © 2015 Elsevier B.V.All rights reserved.
Structural and Magnetic Studies of Thermally Treated NiFe2O4 Nanoparticles
(Springer Boston, 2017) Surajit Ghosh; Prayas Chandra Patel; Debraj Gangopadhyay; Poornima Sharma; Ranjan K. Singh; P.C. Srivastava
The heat treatment of nanoparticles can have a direct effect on their particle sizes, which, in turn, can influence many of their structural and magnetic properties. Here, we report the effect of sintering temperature on the chemically synthesized high-quality NiFe2O4 nanoparticles. The structural studies show the formation of pure NiFe2O4 nanoparticles with the space group Fd3 ¯ m. The inverse spinel structure was also confirmed from the lattice vibrations analyzed from Raman and Fourier transform infrared spectroscopy (FTIR) spectra. The presence of strong exchange interactions was detected from the temperature-dependent magnetization study. Moreover, at higher sintering temperatures, the grain growth due to fusion of several smaller particles by coalescing their surfaces enhances the crystallinity and its magnetocrystalline anisotropy. Coercivity and saturation magnetization were found to depend significantly on the sintering temperature, which was understood in the realm of the formation of single-domain-like structure and change in magnetocrystalline anisotropy at higher sintering temperatures. © 2017, The Minerals, Metals & Materials Society and ASM International.
Study of hydration of sarcosine, formation of its zwitterion and their different oligomers in aqueous media: A Raman spectroscopic and theoretical study
(Elsevier B.V., 2013) Poornima Sharma; Dheeraj K. Singh; Vineet Gupta; B.P. Asthana; P.C. Mishra; Ranjan K. Singh
(Graph Presented) Raman spectra of the biologically important molecule sarcosine (SAR) (C3H7NO2) were studied experimentally in aqueous solution at different concentrations. These spectra were also calculated theoretically using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. Further, all the observed normal modes were assigned through potential energy distribution (PED). Geometry optimization of SAR produced its three conformers with slightly different energies. The lowest energy conformer of SAR was selected for a systematic solvation study wherein different numbers of water molecules (nW, n = 1-9) were placed near it. In the SAR-9W complex, the SAR molecule is located almost at the center of the cage of 9 water molecules. Geometries of different oligomers of SAR (dimer, trimer, tetramer and pentamer) were also optimized in aqueous media taking the input structures from crystallographic data and using the polarizable continuum (PCM). Proton transfer required for the formation of the zwitterionic form of SAR was found to occur when the number of water molecules in the first hydration shell was six or more. © 2013 Elsevier B.V. All rights reserved.
Surface enhanced Raman scattering based reaction monitoring of: In vitro decyclization of creatinine → creatine
(Royal Society of Chemistry, 2016) Debraj Gangopadhyay; Poornima Sharma; Sachin Kumar Singh; Pushkar Singh; Volker Deckert; Jürgen Popp; Ranjan K. Singh
Creatinine → creatine decyclization is an important reaction wherein we obtain a beneficial compound from a toxic substance. Decyclization of creatinine at basic pH has been monitored in vitro by time series surface enhanced Raman scattering (SERS) using a silver island film. NH2 scissoring, CN and CO stretching modes of creatinine serve as Raman markers for monitoring the decyclization reaction. Transition state calculations using DFT have revealed the path of the formation of creatine by the cleavage of the endocyclic CN bond of creatinine. The Raman signatures of ring opening are clearly observed after 120 min at pH 8, and further increasing the pH increases the reaction rate even more, as the signatures are observed after 60 and 30 min at pH 10 and 12, respectively; however, the reversibility of the reaction is more prominent at higher pH. Therefore, pH 8 is the most favorable among the three pH values for the decyclization reaction to be stable at room temperature. The proper understanding of this reaction where a toxic substance is converted to a beneficial compound is expected to open the scope for further extensive research. © The Royal Society of Chemistry 2016.
Temperature dependent polymorphism of pyrazinamide: An in situ Raman and DFT study
(Elsevier B.V., 2018) Poornima Sharma; Rajib Nandi; Debraj Gangopadhyay; Anurag Singh; Ranjan K. Singh
The α and γ polymorphs of drug pyrazinamide have been detected with the help of temperature dependent Raman spectroscopic technique. Pyrazinamide is a very useful drug used for the treatment of tuberculosis (TB) and plays a significant role in destroying the dormant tubercle bacilli which are not destroyed by other common TB drugs. Temperature dependent Raman spectra suggest polymorphic phase change from α → γ form of pyrazinamide between 145 and 146 °C. In situ Raman spectra of pyrazinamide between 145 and 146 °C show the conversion of α → γ form by the shift in C[dbnd]O stretching vibration accompanied by several other changes. The phase change is characterized by the breaking of two linear N[sbnd]H ⋯ O type hydrogen bonds associated with C[dbnd]O stretching vibration in α dimer and formation of one linear N[sbnd]H ⋯ N type hydrogen bond along with a weak intramolecular C[sbnd]H ⋯ O type hydrogen bond in the γ dimer. © 2017
Temperature dependent Raman and DFT study of creatine
(Elsevier, 2015) Debraj Gangopadhyay; Poornima Sharma; Ranjan K. Singh
Temperature dependent Raman spectra of creatine powder have been recorded in the temperature range 420-100 K at regular intervals and different clusters of creatine have been optimized using density functional theory (DFT) in order to determine the effect of temperature on the hydrogen bonded network in the crystal structure of creatine. Vibrational assignments of all the 48 normal modes of the zwitterionic form of creatine have been done in terms of potential energy distribution obtained from DFT calculations. Precise analysis gives information about thermal motion and intermolecular interactions with respect to temperature in the crystal lattice. Formation of higher hydrogen bonded aggregates on cooling can be visualized from the spectra through clear signature of phase transition between 200 K and 180 K. © 2015 Elsevier B.V.