Subrata Chattopadhyay

Publications (121)254.73 Total impact

• Article: Inhibition of TNF-α, and NF-κB and JNK pathways accounts for the prophylactic action of the natural phenolic, allylpyrocatechol against indomethacin gastropathy.

  Sudhir K Yadav, Biplab Adhikary, Sandip K Bandyopadhyay, Subrata Chattopadhyay
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  ABSTRACT: BACKGROUND: The gastro-intestinal disorders, induced by the NSAIDs including indomethacin (IND) remain unresolved medical problems. Herein, we disclose allylpyrocatechol (APC) as a potential agent against IND-gastropathy and rationalize its action mechanistically. METHODS: Mice were pre-treated with APC for 1h followed by IND (18mgkg(-1)) administration, and the ulcer-prevention capacity of APC was evaluated on the 3rd day by histology. Its effect on the inflammatory (MPO, cytokines, adhesion molecules), ulcer-healing (COX, prostaglandins, growth factors and their receptors) and signaling parameters (NF-κB and MAPKs) were assessed by immunoblots/mRNA, and ELISA at the time points of their maximal changes due to IND administration. RESULTS: IND induced oxidative stress, triggering mucosal TNF-α that activated NF-κB and JNKs MAPK signaling in mice. These increased the pro-inflammatory biochemical parameters, but reduced the healing factors. APC reversed all the adverse effects to prevent gastric ulceration. APC (5mgkg(-1)), trolox (50mgkg(-1)) and NAC (250mgkg(-1)) showed similar protection that was better than that by misoprostol (5μgkg(-1)) and omeprazole (3mgkg(-1)). CONCLUSIONS: The anti-ulcer effect of APC can be primarily attributed to its antioxidant action that helped in controlling various inflammatory parameters and augmenting angiogenesis. General Significance Given that APC is an effective, non-toxic antioxidant with appreciable natural abundance, further evaluation of its pharmacokinetics and dynamics would help in promoting it as a new anti-inflammatory agent.
  Biochimica et Biophysica Acta 03/2013; · 4.66 Impact Factor
• Article: Charge transfer energies of the complexes of (dibenzoylmethanato)boron difluoride with indeno-pyridines and polynuclear aromatic hydrocarbons.

  Tandrima Chaudhuri, Sneha Salampuria, Pradip Kumar Tapaswi, Chhanda Mukhopadhyay, Subrata Chattopadhyay, Manas Banerjee
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  ABSTRACT: Charge transfer complexes of electron deficient (dibenzoylmethanato)boron difluoride (DBMBF2) with polyaromatic hydrocarbons (A), as well as with highly electron rich indeno-pyridines (I) compounds in ethanol medium have been studied by electronic absorption spectroscopy. Absorption band due to a charge-transfer (CT) transitions are observed in the visible region. Utilizing the CT transition energy, the vertical electron affinities (EAv) of DBMBF2 in ethanol has been calculated. The value of EAv for DBMBF2 is found to be 2.28eV, this is the first report of its electron affinity value. We have calculated the degrees of CT and transition dipole strengths of the DBMBF2/A and DBMBF2/I complexes. Along with both theoretically calculated and experimentally obtained vertical ionization potentials of the indeno-pyridine donors have been estimated for the first time. I show high degree of charge transfer along with high ground state stability similar to that of A. Thus indeno-pyridine (I) donors are also as good as aromatic hydrocarbons (A) for DBMBF2, having equivalent ionization potential like that of aromatic hydrocarbons.
  Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2013; 108C:181-185. · 2.10 Impact Factor
• Article: Bioethics and Its Gatekeepers: Does Institutional Racism Exist in Leading Bioethics Journals?

  Subrata Chattopadhyay, Catherine Myser, Raymond De Vries
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  ABSTRACT: Who are the gatekeepers in bioethics? Does editorial bias or institutional racism exist in leading bioethics journals? We analyzed the composition of the editorial boards of 14 leading bioethics journals by country. Categorizing these countries according to their Human Development Index (HDI), we discovered that approximately 95 percent of editorial board members are based in (very) high-HDI countries, less than 4 percent are from medium-HDI countries, and fewer than 1.5 percent are from low-HDI countries. Eight out of 14 leading bioethics journals have no editorial board members from a medium- or low-HDI country. Eleven bioethics journals have no board members from low-HDI countries. This severe underrepresentation of bioethics scholars from developing countries on editorial boards suggests that bioethics may be affected by institutional racism, raising significant questions about the ethics of bioethics in a global context.
  Journal of Bioethical Inquiry 01/2013; · 0.54 Impact Factor
• Article: [bmim][Br], as a Solvent and Activator for the Ga-mediated Barbier Allylation: Direct Formation of a N-Heterocyclic Carbene from Ga-metal.

  Dibakar Goswami, Angshuman Chattopadhyay, Anubha Sharma, Subrata Chattopadhyay
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  ABSTRACT: The room temperature ionic liquid (RTIL) [bmim][Br] has been found to be an excellent green and inexpensive medium for the Ga-mediated allylation of aromatic and aliphatic aldehydes and ketones. The RTIL activated the metal via formation of a Ga-N-heterocyclic carbene complex that assisted to carry out the reaction at an ambient temperature, and with only 0.5 equiv. of Ga and 1.2 equiv. of allyl bromide with respect to the carbonyl substrates. The present protocol required much shorter time than those reported in literature using other metals and solvents, and proceeded with good yields and excellent selectivity.
  The Journal of Organic Chemistry 11/2012; · 4.45 Impact Factor
• Article: Inhibition in binding between fullerene and bisporphyrin in presence of silver nanoparticles: A new physicochemical insight into fullerene-bisporphyrin complexation in solution.

  Ratul Mitra, Subrata Chattopadhyay, Sumanta Bhattacharya
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  ABSTRACT: The present paper reports non-covalent interaction between fullerenes (C(60) and C(70)) and a designed bisporphyrin (1) in p-xylene in absence and presence of silver nanoparticles (AgNp) having diameter ∼5-15nm. Both UV-vis and fluorescence experiments reveal reduction in the average binding constant (K(av)) value for C(60)-1 (K(C60-)(1)=27,980dm(3)mol(-1)) and C(70)-1 systems (K(C70-)(1)=115,020dm(3)mol(-1)) in presence of AgNp, i.e., K(C60-)(1)(-AgNp)=22,465dm(3)mol(-1) and K(C70-)(1)(-AgNp)=30,830dm(3)mol(-1). Dynamic light scattering experiment gives clear indication regarding formation of larger aggregates as a result of electrostatic attraction between porphyrin-based supramolecule and AgNp in solution. Scanning electron microscope measurement reveals formation of molecular cluster comprising C(70)-1-AgNp composite.
  Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2012; 102C:358-364. · 2.10 Impact Factor
• Article: Respect for cultural diversity in bioethics is an ethical imperative.

  Subrata Chattopadhyay, Raymond De Vries
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  ABSTRACT: The field of bioethics continues to struggle with the problem of cultural diversity: can universal principles guide ethical decision making, regardless of the culture in which those decisions take place? Or should bioethical principles be derived from the moral traditions of local cultures? Ten Have and Gordijn (Medicine, Health Care and Philosophy 14:1-3, 2011) and Bracanovic (Medicine, Health Care and Philosophy 14:229-236, 2011) defend the universalist position, arguing that respect for cultural diversity in matters ethical will lead to a dangerous cultural relativity where vulnerable patients and research subjects will be harmed. We challenge the premises of moral universalism, showing how this approach imports and imposes moral notions of Western society and leads to harm in non-western cultures.
  Medicine Health Care and Philosophy 09/2012; · 0.91 Impact Factor
• Source

  Available from: Saikat Chakraborty

  Article: DL-trans-3,4-Dihydroxy-1-selenolane (DHSred) accelerates healing of indomethacin-induced stomach ulceration in mice

  Saikat Chakraborty, Sudhir K. Yadav, Mahesh Subramanian, K. I. Priyadarsini, Michio Iwaoka, Subrata Chattopadhyay
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  ABSTRACT: Management of the gastro-toxicity of non-steroidal anti-infl ammatory drugs (NSAIDs) remains a crucial problem, because the commercially available anti-ulcer drugs have side effects and are often expensive. Hence, we examined the potential of a new water-soluble GPx mimic, DL- trans-3,4-dihydroxy-1-selenolane (DHS red ) in healing the indomethacin-induced stomach ulceration in mice. Administration of indomethacin (18 mg/kg, po) induced ulceration in the glandular portion of the gastric mucosa, accompanied by increased lipid peroxidation (1.3 fold, p<0.001) and protein oxidation (1.5 fold, p<0.001), depletion of thiol-defense (42.5%, p<0.01), plasma total antioxidant status (53.4%, p<0.001) and mucin (47.5%, p<0.01), as well as reduced expressions of cyclooxygenases and prostaglandin synthesis (54.7%, p<0.001) in the gastric tissues of mice. Daily oral administration of DHS red (2.5 mg/kg) or omeprazole (Omez) (3 mg/kg) for 3 days respectively produced ∼74% and 69% ( p<0.001) healing of the acute gastric ulceration. The test samples also signifi cantly reversed all the adverse effects of indomethacin on the biochemical parameters. Apparently, the gastric ulcer healing action of DHS red and Omez was due to their antioxidant action, and ability to protect mucin and augment PG synthesis by upregulation of the COX isozymes. The results suggested that the non-toxic and inexpensive compound, DHS red may be a good candidate for further evaluation as a potent anti-ulcer drug
  Free Radical Research 08/2012; · 2.88 Impact Factor
• Article: Ellagic acid facilitates indomethacin-induced gastric ulcer healing via COX-2 up-regulation.

  Ananya Chatterjee, Sirshendu Chatterjee, Smita Das, Arpita Saha, Subrata Chattopadhyay, Sandip K Bandyopadhyay
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  ABSTRACT: The mechanism of indomethacin-induced gastric ulcer healing by ellagic acid (EA) in experimental mice model is described in our study. Ulcer index (UI) and myeloperoxidase (MPO) activity of the stomach tissues showed maximum ulceration on the third day after indomethacin (18 mg/kg, single dose) administration. Preliminary observation of UI and MPO activity suggests that EA possesses ulcer-healing activity. Other anti-ulcer parameters such as the levels of prostaglandin E(2), cyclooxygenase (COX) 1 and 2 enzymes, anti-inflammatory cytokines [interleukin (IL)-4 and -5], pro-angiogenic factors, e.g. vascular endothelial growth factor, hepatocyte growth factor (HGF), and endothelial growth factor (EGF) were down-regulated by indomethacin. EA (7 mg/kg/day) treatment for 3 days shifted the indomethacin-induced pro-inflammatory biochemical parameters to the healing side. These activities were correlated with the ability of EA to alter the COX-2-dependent healing pathways. The ulcer-healing activity of EA was, however, compromised by pre-administration of the specific COX-2 inhibitor, celecoxib, and NS-398. Taken together, these results suggested that the EA treatment accelerates ulcer healing by inducing IL-4, EGF/HGF levels and enhances COX-2 expression.
  Acta Biochimica et Biophysica Sinica 05/2012; 44(7):565-76. · 1.38 Impact Factor
• Article: The Antioxidant Activity of Allylpyrocatechol is Mediated via Decreased Generation of Free Radicals Along With Escalation of Antioxidant Mechanisms.

  Debjani Sarkar, Sunanda Kundu, Soumita De, Chellaram Hariharan, Piu Saha, Alak Manna, Subrata Chattopadhyay, Mitali Chatterjee
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  ABSTRACT: Allylpyrocatechol (APC) is responsible for the antiinflammatory activity exhibited by the methanolic extract of leaves of Piper betle. As antiinflammatory compounds may display antioxidant properties and vice versa, we investigated the antioxidant effect of APC. APC effectively reduced phorbol-myristate-acetate-induced generation of reactive oxygen species and superoxide in murine peritoneal macrophages as well as inhibited Escherichia-coli-induced phagocytic activity of macrophages. Furthermore, pBluescript SK(+) plasmid DNA damage induced by addition of sodium ascorbate was attenuated by APC as it inhibited transformation of the supercoiled form to a relaxed form. In addition, APC increased the enzymatic (catalase) and nonenzymatic (GSH) antioxidant components of murine macrophages. Taken together, APC exhibited an antioxidant activity which was mediated both via decreased generation of free radicals along with increase in cellular antioxidants. Copyright © 2012 John Wiley & Sons, Ltd.
  Phytotherapy Research 05/2012; · 2.09 Impact Factor
• Article: Absorption Spectrophotometric, NMR and Quantum Chemical Investigations of Ground State Non-Covalent Interactions between Fullerenes and a Designed Trihomocalix[6]arene in Solution

  Amal Halder, Sandip K. Nayak, Suchitra Bhat, Subrata Chattopadhyay, Sumanta Bhattacharya
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  ABSTRACT: Ground state non-covalent interactions between a newly designed macrocyclic 1,3,5-trihomo calix[6]arene receptor, designated as 1, and the C60 and C70 fullerenes have been studied in toluene solutions. It was observed that the absorbances of both C60 and C70 solutions increased upon the addition of increasing concentrations of compound 1. Job’s method of continuous variation established 1:1 stoichiometry for these fullerene-1 complexes. The binding constant (K) data reveal that compound 1 binds to C70 more strongly compared to C60, i.e., KC60-1 = 230dm3mol-1K_{C60\mbox{-}\boldsymbol{1}} = 230~\mathrm{dm}^{3}{\cdot}\mathrm{mol}^{-1} and KC70-1 = 517dm3mol-1K_{C70\mbox{-}\boldsymbol{1}}= 517~\mathrm{dm}^{3}{\cdot}\mathrm{mol}^{-1}. Proton NMR analysis provides very good support for strong binding between C70 and1. Estimations of the solvent reorganization energy (R S ) suggest that the C70-1 complex is stabilized more than the corresponding C60-1 complex, with RS(C60-1) = -1.970eVR_{S(C60\mbox{-}\boldsymbol{1})} = -1.970~\mathrm{eV} and RS(C70-1) = -2.300eVR_{S(C70\mbox{-}\boldsymbol{1})}= -2.300~\mathrm{eV}. Molecular mechanics force field method calculations established that the binding pattern of C70 towards 1 occurs in the side-on rather than end-on orientation, and that the C70-1 complex gains 5.23kJ⋅mol−1 of extra stabilization energy with this side-on geometrical arrangement. KeywordsFullerenes C60 and C70 –1,3,5-trihomo-calix[6]arene–UV-Vis spectroscopy– 1H NMR–MMMF calculations
  Journal of Solution Chemistry 04/2012; 40(6):929-943. · 1.41 Impact Factor
• Article: Where are all the bioethicists when you need them?

  Subrata Chattopadhyay, John J Gillon, Raymond De Vries
  Journal of the Royal Society of Medicine 04/2012; 105(4):143-5. · 1.41 Impact Factor
• Article: Physicochemical insights in supramolecular interaction of fullerenes C60 and C70 with a monoporphyrin in presence of silver nanoparticles.

  Ratul Mitra, Subrata Chattopadhyay, Sumanta Bhattacharya
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  ABSTRACT: The present article reports for the first time on supramolecular interaction between fullerenes (C60 and C70) and a designed monoporphyrin in solution, e.g., 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine (1), in absence and presence of silver nanoparticles (AgNp) having varying diameter of range between 3 and 7 nm. Ground state electronic interaction between fullerenes and 1 has been evidenced from the observation of decrease in the intensity of the Soret absorption band of 1 after complexation with C60 and C70 in toluene. However, in presence of AgNp, extent of decrease in the intensity of Soret absorption band of 1 has been reduced following its complexation with fullerenes. Steady state fluorescence measurements establish quenching of fluorescence of 1 by fullerenes and the most interesting aspect of the present work is that quenching efficiencies of C60 and C70 are found to be less in presence of AgNp. Steady state fluorescence measurement reveals reduction in the binding constant (K) value for both C60-1 (KC60-1=2355 dm3 mol(-1) and C70-1 complex (KC70-1=11,980 dm3 mol(-1)) in presence of AgNp (KC60-1=340 and KC70-1=7380 dm3 mol(-1)). The new physical insight of the present studies is that 1 acts as excellent discriminator molecule for C70 in presence of AgNp as selectivity in binding is estimated to be ∼21.7 in presence of AgNp compared to the situation when fullerene-1 mixture does not contain any AgNp (i.e., selectivity in binding=∼5.0) in solution. Time-resolved fluorescence studies establish the role of static quenching mechanism behind fluorescence decay of 1 by fullerenes in absence and presence of AgNp. Magnitude of rate constant for charge separation and quantum yield of charge separation indicates that C70-1 complex exhibits highest value of such parameters in absence of AgNp compared to the situation when AgNp particles are present in the composite mixture of C70 and 1. Dynamic light scattering (DLS) measurement reveals while particle size of AgNp is estimated to be ∼4.8-5.0 nm in presence of 1, the size of the AgNp particles in 1 become larger in presence of C60 (∼13.0 nm) and C70 (∼37.0 nm) solution in toluene. Conductance measurement establishes that AgNp particles reduce the generation of electrical conductivity value for both C60-1 and C70-1 systems in toluene with respect to time; the rate of decrease of electrical conductivity become much slower in presence of C70-1 complex. Scanning electron microscopic experiment provides excellent support for DLS measurements regarding increase in the size of the nanoparticles in presence of C60 and C70. Transmission electron microscope clearly demonstrates that the electrostatic attraction between porphyrin-based supramolecules and silver nanoparticles is very much responsible behind the formation of larger aggregates. Semiempirical PM3 calculations in vacuo establish the single projection structures for the fullerene-1 complexes and well interpret the stability difference between C60- and C70-complexes of 1 in terms of heat of formation values of the respective complexes.
  Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2012; 89:284-93. · 2.10 Impact Factor
• Source

  Available from: Biswanath Maity

  Article: Molecular mechanism of indomethacin-induced gastropathy.

  Sudhir K Yadav, Biplab Adhikary, Saswati Chand, Biswanath Maity, Sandip K Bandyopadhyay, Subrata Chattopadhyay
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  ABSTRACT: The probable cross talk among large numbers of inflammatory and angiogenic parameters in indomethacin (IND)-induced gastropathy and the associated signaling mechanism were studied in a mouse model. A single dose of IND (18 mg/kg, po) produced robust gastric ulceration in mice without any mortality, which peaked on the third day, but started healing from the fifth day onward. The ulceration was associated with increased myeloperoxidase activity and expression of proinflammatory (TNF-α, adhesion molecules, COX-2) and antiangiogenic (endostatin) parameters. The levels of proangiogenic factors such as COX-1, prostaglandin E, VEGF, and von Willebrand factor VIII were downregulated by IND. Our results revealed that although the maximal and minimal levels of these parameters were attained sequentially at different time points, TNF-α upregulation was the primary event to initiate and induce gastric ulceration. IND also activated NF-κB and all the MAP kinases, but only the inhibitors of TNF-α, NF-κB, and JNK MAP kinase could abrogate the IND-induced damages. Further TNF-α inhibition also reduced the IND-mediated activation of NF-κB and JNK MAP kinase. All this evidence strongly suggests that mitigation of TNF-α may offer a potential solution to IND-mediated gastropathy.
  Free radical biology & medicine 04/2012; 52(7):1175-87. · 5.42 Impact Factor
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  Available from: Mrityunjay Tyagi

  Article: Molecular mechanism of the anti-inflammatory activity of a natural diarylnonanoid, malabaricone C.

  Biswanath Maity, Sudhir Kumar Yadav, Birija S Patro, Mrityunjay Tyagi, Sandip Kumar Bandyopadhyay, Subrata Chattopadhyay
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  ABSTRACT: The spice-derived phenolic, malabaricone C (mal C), has recently been shown to accelerate healing of the indomethacin-induced gastric ulceration in mice. In this study, we explored its anti-inflammatory activity and investigated the underlying mechanism of the action. Mal C suppressed the microvascular permeability and the levels of tumor necrosis factor-α, interleukin-1β, and nitric oxide in the lipopolysaccharide (LPS)-administered mice. At a dose of 10 mg/kg, it showed anti-inflammatory activity comparable to that of omeprazole (5 mg/kg) and dexamethasone (50 mg/kg). It also reduced the expression and activities of inducible nitric oxide synthase, cyclooxygenase-2, as well as the pro- vs anti-inflammatory cytokine ratio in the LPS-treated RAW macrophages. Mal C was found to inhibit LPS-induced NF-kB activation in RAW 264.7 cells by blocking the MyD88-dependent pathway. Mal C suppressed NF-κB activation and iNOS promoter activity, which correlated with its inhibitory effect on IκB phosphorylation and degradation, and NF-κB nuclear translocation, in the LPS-stimulated macrophages. It also inhibited LPS-induced phosphorylation of p38 and JNK, which are also upstream activators of NF-κB, without affecting Akt phosphorylation. Mal C also effectively blocked the PKR-mediated activation of NF-κB. These findings indicate that mal C exerts an anti-inflammatory effect through NF-κB-responsive inflammatory gene expressions by inhibiting the p38 and JNK-dependent canonical NF-κB pathway as well as the PKR pathway, and is a potential therapeutic agent against acute inflammation.
  Free radical biology & medicine 02/2012; 52(9):1680-91. · 5.42 Impact Factor
• Article: Absorption spectrophotometric, NMR and theoretical investigations on ground state non-covalent interaction of C₆₀ and C₇₀ with a designed trihomocalix[6]arene in solution.

  Amal Halder, Kshama Kundu, Sandip K Nayak, Subrata Chattopadhyay, Sumanta Bhattacharya
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  ABSTRACT: The present paper reports the spectroscopic investigations on non-covalent interaction of fullerenes C(60) and C(70) with a designed trihomocalix[6]arene (2) in toluene. UV-vis studies reveal appreciable ground state interaction between fullerenes and 2. Jobs method of continuous variation establishes 1:1 stoichiometry for fullerene-2 complexes. Binding constant (K) data reveals that 2 binds C(70) more strongly compared to C(60), i.e. K(C60-2)-47,540 dm(3)mol(-1) and K(C70-2)-86,360 dm(3)mol(-1). Proton NMR studies provide very good support in favor of strong binding between C(70) and 2. Estimation of solvent reorganization energy (R(S)) evokes that C(70)-2 complex is stabilized more compared to C(60)-2 complex as R(S(C60-2))- -1.162 eV and R(S(C70-2))- -1.244eV. Semiempirical calculations at third parametric level of theory in vacuo evoke the single projection structures of the fullerene-2 complexes and interpret the stability difference between C(60) and C(70) complexes of 2 in terms of enthalpies of formation values.
  Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2012; 93:384-9. · 2.10 Impact Factor
• Article: Gallic Acid Enriched Fraction of Phyllanthus emblica Potentiates Indomethacin-Induced Gastric Ulcer Healing via e-NOS-Dependent Pathway.

  Ananya Chatterjee, Sirshendu Chatterjee, Angshuman Biswas, Sayanti Bhattacharya, Subrata Chattopadhyay, Sandip K Bandyopadhyay
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  ABSTRACT: The healing activity of gallic acid enriched ethanolic extract (GAE) of Phyllanthus emblica fruits (amla) against the indomethacin-induced gastric ulceration in mice was investigated. The activity was correlated with the ability of GAE to alter the cyclooxygenase- (COX-) dependent healing pathways. Histology of the stomach tissues revealed maximum ulceration on the 3rd day after indomethacin (18 mg/kg, single dose) administration that was associated with significant increase in inflammatory factors, namely, mucosal myeloperoxidase (MPO) activity and inducible nitric oxide synthase (i-NOS) expression. Proangiogenic parameters such as the levels of prostaglandin (PG) E(2), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), von Willebrand Factor VIII, and endothelial NOS (e-NOS) were downregulated by indomethacin. Treatment with GAE (5 mg/kg/day) and omeprazole (3 mg/kg/day) for 3 days led to effective healing of the acute ulceration, while GAE could reverse the indomethacin-induced proinflammatory changes of the designated biochemical parameters. The ulcer healing activity of GAE was, however, compromised by coadministration of the nonspecific NOS inhibitor, N-nitro-L-arginine methyl ester (L-NAME), but not the i-NOS-specific inhibitor, L-N6-(1-iminoethyl) lysine hydrochloride (L-NIL). Taken together, these results suggested that the GAE treatment accelerates ulcer healing by inducing PGE(2) synthesis and augmenting e-NOS/i-NOS ratio.
  Evidence-based Complementary and Alternative Medicine 01/2012; 2012:487380. · 4.77 Impact Factor
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  Available from: Debanjan Mukhopadhyay

  Article: Malabaricone-A induces a redox imbalance that mediates apoptosis in U937 cell line.

  Alak Manna, Piu Saha, Avijit Sarkar, Debanjan Mukhopadhyay, Ajay K Bauri, Deepak Kumar, Padma Das, Subrata Chattopadhyay, Mitali Chatterjee
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  ABSTRACT: The 'two-faced' character of reactive oxygen species (ROS) plays an important role in cancer biology by acting both as secondary messengers in intracellular signaling cascades and sustaining the oncogenic phenotype of cancer cells, while on the other hand, it triggers an oxidative assault that causes a redox imbalance translating into an apoptotic cell death. Using a tetrazolium [{3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl}-2H-tetrazolium] based cell viability assay, we evaluated the cytotoxicity of a plant derived diarylnonanoid, malabaricone-A on leukemic cell lines U937 and MOLT-3. This cytotoxicity hinged on its ability to cause a redox imbalance via its ability to increase ROS, measured by flow cytometry using 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate and by decreasing glutathione peroxidase activity. This redox imbalance mediated apoptosis was evident by an increase in cytosolic [Ca(2+)], externalization of phosphatidyl serine as also depolarization of the mitochondrial membrane potential as measured by flow cytometry. There was concomitant peroxidation of cardiolipin, release of free cytochrome c to cytosol along with activation of caspases 9, 8 and 3. This led to cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by labeling with 4',6-diamidino-2-phenylindole (DAPI); furthermore, terminal deoxy ribonucleotide transferase catalysed incorporation of deoxy uridine triphosphate confirmed DNA nicking and was accompanied by arrest of cell cycle progression. Taken together, compounds like MAL-A having pro-oxidant activity mediate their cytotoxicity in leukemic cells via induction of oxidative stress triggering a caspase dependent apoptosis.
  PLoS ONE 01/2012; 7(5):e36938. · 4.09 Impact Factor
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  Available from: Neelam Shivran

  Article: Steric strain release-directed regioselective functionalization of meso-methyl Bodipy dyes.

  Neelam Shivran, Soumyaditya Mula, Tapan K Ghanty, Subrata Chattopadhyay
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  ABSTRACT: Starting from some meso-methyl Bodipy dyes, the corresponding meso-styryl derivatives were synthesized by regioselective Knoevenagel-type condensation with different aromatic aldehydes. The reactions were driven by the alleviation of the structural strain of the alkyl substituted Bodipys that could override the differential acidities of the methyl protons at the pyrrole ring of the Bodipy moiety.
  Organic Letters 11/2011; 13(21):5870-3. · 5.86 Impact Factor
• Article: UV-Vis, fluorescence and NMR spectroscopic investigations on inclusion properties of a designed tetrahomocalix[8]arene with fullerenes C60 and C70 in solution.

  Amal Halder, Suchitra Bhatt, Sandip K Nayak, Subrata Chattopadhyay, Sumanta Bhattacharya
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  ABSTRACT: The present article reports the spectroscopic investigations on non-covalent interaction of fullerenes C(60) and C(70) with a macrocyclic receptor molecule, namely, 1,3,5,7-tetrahomo-p-tert-butylcalix[8]arene (1) in toluene. Jobs method of continuous variation reveals 1:1 stoichiometry for the fullerene complexes of 1. The most fascinating feature of the present study is that 1 binds selectively C(60) compared to C(70) as obtained from binding constant (K) data of C(60)-1 (K(C60-1)) and C(70)-1 (K(C70-1)) complexes which are enumerated to be 265,000 dm(3) mol(-1) and 63,43 dm(3) mol(-1), respectively, and selectivity in binding (K(C60-1)/K(C70-1)) is estimated to be 4.18 as obtained from UV-Vis study. Steady state fluorescence studies reveal quenching of fluorescence of 1 in presence of fullerenes and the K value of the C(60)-1 and C(70)-1 complexes are estimated to be 80,760 and 68,780 dm(3) mol(-1), respectively, with selectivity in binding (K(C60-1)/K(C70-1)) ~1.18. (1)H NMR analysis provides very good support in favor of strong binding between C(60) and 1. The high value of K value for C(60)-1 complex indicates that 1 forms an inclusion complex with C(60).
  Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 08/2011; 84(1):25-31. · 2.10 Impact Factor
• Article: Black tea and theaflavins suppress various inflammatory modulators and i-NOS mediated nitric oxide synthesis during gastric ulcer healing.

  Biplab Adhikary, Sudhir K Yadav, Saswati Chand, Sandip K Bandyopadhyay, Subrata Chattopadhyay
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  ABSTRACT: The modulation of the cyclooxygenase-independent pathway by black tea (BT) and its constituent theaflavins (TFs) during their healing action against indomethacin-induced stomach ulceration in mice was investigated. On the 3(rd) day of its administration, indomethacin (18 mg/kg) induced maximum stomach ulceration, which was associated with increased myeloperoxidase (MPO) activity (93.3%, p<0.001), and inducible nitric oxide synthase (iNOS) expression (1.6-fold, p<0.001), along with augmented levels of serum nitrite (1.5-fold, p<0.001), selectins and cell adhesion molecules (CAMs), as well as reduced endothelial nitric oxide synthase (eNOS) expression (60%, p<0.001). Treatment with BT (40 mg/kg) and TF (1 mg/kg) for 3 days reversed these parameters and provided excellent (78-81%) ulcer healing. However, alterations of NOS expressions and levels of selectins and CAMs were only partially responsible for the excellent healing capacity (∼80%) of omeprazole (3 mg/kg × 3 days).
  Free radical research 07/2011; 45(7):767-78. · 2.22 Impact Factor