Entity

Time filter

Source Type


Gayen P.,Jadavpur University | Gayen P.,Raja Peary Mohan College | Sinha C.,Jadavpur University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The UV light irradiation to a solution of 1-alkyl-2-(arylazo)imidazole (L) in toluene shows transformation of trans to cis configuration about NN bond. The rate of photo-isomerisation and quantum yields are influenced by internal parameters like-nature of substituents, coordination to metal ions, steric and electronic effect, protonation etc. and the external factors like solvent (polarity, viscosity, dipole moment etc.), presence of innocent (to be chemically noninteracting) and noninnocent (chemically interacting) ions or molecules. In this work the influence of polycyclic aromatic hydrocarbons (PAH) such as-napththalene, anthracene, phenanthrene, pyrene-an innocent system, on the photochromic efficiency of L has been examined. The PAHs are π-donor and may form a π-π continuum with L which can significantly affect the motional (vibration, rotation) properties of the analyte and hence the photochromic activity. The rate and quantum yield of trans-to-cis isomerisation of L decrease with increasing [PAH] and also with increasing number of the fused phenyl ring(s) in PAH. Thus the photoisomerisation follows the rate sequence: no PAH > napththalene > anthracene-phenanthrene > pyrene. The reverse change, cis-to-trans is very slow upon light irradiation while appreciably fast in thermal process at dark. The activation energy (Ea) also decreases with [PAH] and number of fused phenyl rings. © 2012 Elsevier B.V. All rights reserved. Source


Ren X.,University of Illinois at Chicago | Dwivedi Y.,University of Illinois at Chicago | Mondal A.C.,Raja Peary Mohan College | Pandey G.N.,University of Illinois at Chicago
Psychiatry Research | Year: 2011

Cyclic-AMP response element binding (CREB) protein regulates the expression of many genes involved in the pathophysiology of depression. Increased CREB levels were found in the brain of antidepressant-treated rats and decreased protein and mRNA expression of CREB was reported in the postmortem brain of depressed suicide victims. We determined CREB protein expression, using Western blot technique, and CRE-DNA binding, using gel shift assay, in neutrophils obtained from 22 drug-free patients with major depressive disorder (MDD) and 23 normal control subjects. Diagnosis of patients was based on Diagnostic and Statistical Manual of Mental Disorders DSM-IV criteria; severity of illness was rated by Hamilton Depression Rating Scale (HDRS). We found that the CRE-DNA binding activity and CREB protein expression were significantly decreased in the neutrophils of drug-free MDD patients compared with normal control subjects. Our findings suggest that CREB may play an important role in the pathophysiology of depression and that it may be an important target for the therapeutic action of antidepressant drugs. Neutrophil CREB levels may also serve as a useful biomarker for patients with MDD. © 2010 Elsevier Ltd. Source


Gayen P.,Raja Peary Mohan College | Sarker K.K.,Mahadevananda Mahavidyalaya | Sinha C.,Jadavpur University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2013

Photochromism is dependent on the structure of material and matrix. 1-Alkyl-2-(arylazo)imidazole exists at ambient condition in trans-geometry about NN group. UV light irradiation in toluene solution of the compound has changed their trans structure to cis structure. These two isomers have different absorption spectra. The cis-to-trans isomerization proceeds slowly in visible light irradiation while it is appreciably fast with increasing temperature under thermal process. The rate of trans-to-cis isomerization is increased by 30-70% in presence of neutral (Triton-X-100) and cation (CTAB) micelle while anion micelle (SDS) reduces the same by 34-49%. The quantum yield of the photoisomerization is also increased by 33-84% in presence of neutral and cationic micelle. The activation energy (Ea) of cis→trans thermal isomerization is amplified in presence of Triton-X-100 and CTAB while it is decreased by adding SDS. Thus, the lowering of cis-to-trans thermal process in presence of neutral and cation micelle and increasing in SDS phase is justified. © 2013 Elsevier B.V. Source


Gayen P.,Jadavpur University | Gayen P.,Raja Peary Mohan College | Sinha C.,Jadavpur University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2012

The photoisomerization of 1-alkyl-2-(arylazo)imidazole, trans-to-cis, has been studied in the matrix of PEG-200 and Tween-20 in toluene medium by UV light irradiation. The trans and cis-isomers have different absorption spectra. The cis-to-trans isomerization proceeds slowly in visible light irradiation while it is appreciably fast in thermal process. The rate of trans-to-cis isomerization is decreased by 30-60% in presence of PEG-200 and Tween-20. The quantum yield of the photoisomerization is also decreased by 35-55% and follows the rate sequence: free state > PEG-200-phase > Tween-20 phase. The activation energy (Ea) of cis → trans, thermal backward isomerization, is reduced in PEG-200 and Tween-20 phase following free state > PEG-200-phase > Tween-20-phase. The branched polyhydroxo structure of Tween-20 may help to wrap the polar photochrome more efficiently than major ether functionalized PEG-200 and stabilizes trans-isomer. © 2012 Elsevier B.V. All rights reserved. Source


Banerjee R.,Raja Peary Mohan College | Hazra S.,Raja Peary Mohan College | Ghosh A.K.,Jadavpur University | Mondal A.C.,Raja Peary Mohan College
Psychiatry Investigation | Year: 2014

Objective The present study aimed to investigate whether graded doses of Bacopa Monniera (BM) extract could produce antidepressant-like effects in chronic unpredictable stress (CUS) induced depression in rats and its possible mechanism(s). Methods Rats were subjected to an experimental setting of CUS. The effect of BM extract treatment in CUS-induced depression was examined using behavioral tests including the sucrose consumption, open field test and shuttle box escape test. The mechanism underlying the antidepressant-like action of BM extract was examined by measuring brain-derived neurotrophic factor (BDNF) protein and mRNA expression in brain tissues of CUS-exposed rats. Results Exposure to CUS for 4 weeks caused depression-like behavior in rats, as indicated by significant decreases in sucrose consumption, locomotor activity and escape latency. In addition, it was found that BDNF protein and mRNA levels in the hippocampus and frontal cortex were lower in CUS-treated rats, as compared to controls. Daily administration of the graded doses of BM extract during the 4-week period of CUS significantly suppressed behavioral changes and attenuated the CUS-induced decrease in BDNF protein and mRNA levels in the hippocampus and frontal cortex. Conclusion The results suggest that BM extract alleviates depression induced by CUS. Present study also confirms that 80-120 mg/kg doses of BM extract have significantly higher antidepressant-like activity. © 2014 Korean Neuropsychiatric Association. Source

Discover hidden collaborations