Atanu Barik

Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

Are you Atanu Barik?

Claim your profile

Publications (28)66.41 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Metal-based photosensitizers of the type [Co(L)Cl2] (1), [Ni(L)Cl2] (2) and [Cu(L)]Cl2 (3), where L= N’1,N’3-bis[(E)-thiophen-2-ylmethylidene]benzene-1,3-dicarbohydrazide have been synthesized and characterized by advanced spectroscopic and analytical techniques. The interactions of the complexes with CT DNA were investigated by viscosity analysis, thermal denaturation and absorption spectroscopic techniques. Absorption spectral (Kb = 5.57×104 M-1 (1), 4.45×104 M-1 (2), 2.8×104 M-1 (3)), thermal denaturation and viscosity measurements reveal that 1, 2 and 3 interact with DNA through intercalation. The complexes are photocleavers of SC pUC19 DNA in UV-A light forming 1O2 as the reactive oxygen species. The in-vitro cytotoxicity of 1, 2 and 3 towards MCF-7 tumor cell lines has been evaluated by MTT method, and show an enhancement of cytotoxicity in UV-A light. The results revealed that complex 1 has superior prospectus to act as cancer chemotherapeutic candidate than that of complex 2 and complex 3.
    Inorganica Chimica Acta 02/2015; 428. DOI:10.1016/j.ica.2014.12.032 · 2.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new class of Cu(II) and Co(II) complexes of azo-containing Schiff base of the type [Cu(L1)2] and [Co(L1)2], where L1=4-[(E)-{2-hydroxy-3-[(E)-(4-bromophenyl)diazenyl]benzylidene}amino]benzoic acid have been synthesized and characterized. Extension of conjugation and the presence of free carboxylic acid group of the ligand L1 increased the wavelength of the complexes from visible region to the near IR region (620-850nm). The Cu(II) and Co(II) complexes interacted with CT-DNA via intercalative mode with the respective Kb value of 3.2×10(4)M(-1) and 2.9×10(4)M(-1) and acted as proficient photocleavers of SC pUC19 DNA in UV-A light, forming (1)O2 as the reactive oxygen species with the quantum yield of 0.38 and 0.36, respectively. Furthermore, the Cu(II) and Co(II) complexes showed photocytotoxicity toward two selected tumor cell lines MCF-7 and A549 by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) method, and the Cu(II) complex exhibits higher photocytotoxicity than Co(II) complex against each of the selected cell lines, this result is identical with their DNA binding ability order. Copyright © 2015 Elsevier B.V. All rights reserved.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 01/2015; 141C:34-42. DOI:10.1016/j.saa.2015.01.019 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: One electron redox reaction of two asymmetric 3,5-dimethyl pyrazole derivatives of selenoethers attached to ethanoic acid (DPSeEA) and propionic acid (DPSePA) were studied by pulse radiolysis technique using transient absorption detection. The reaction of the hydroxyl ((•)OH) radical with DPSeEA or DPSePA at pH 7 produced transients absorbing at 500 nm and at 300 nm, respectively. The absorbance at 500 nm increased with increasing parent concentration indicating formation of dimer radical cations. From the absorbance changes, the equilibrium constants for the formation of dimer radical cation of DPSeEA and DPSePA were estimated as 2020 and 1608 M(-1), respectively. The rate constants at pH 7 for the reaction of the (•)OH radical with DPSeEA and DPSePA were determined to be 9.6 × 10(9) and 1.4 × 10(10) M(-1) s(-1), respectively. The dimer radical cation of DPSeEA and DPSePA decayed by first order kinetics with a rate constant of 2.8 × 10(4) and 5.5 × 10(3) s(-1), respectively. The yield of radical cations of DPSeEA and DPSePA were estimated from the secondary electron transfer reaction, which corresponds to 38% and 48% of (•)OH radical yield, respectively. Some fraction of monomer radical cation undergoes decarboxylation reaction, and the yield of decarboxylation was 25% and 20% for DPSeEA and DPSePA, respectively. These results have implication in understanding their antioxidant activity. The reaction of trichloromethyl peroxyl radical, glutathione, and ascorbic acid further support their antioxidant behavior.
    The Journal of Physical Chemistry A 10/2014; 118(44). DOI:10.1021/jp507369q · 2.78 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present investigation, a Schiff base N'(1),N'(3)-bis[(Z)-(2-hydroxynapthyl)methylidene]benzene-1,3-dicarbodihydrazide (L1) and its Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized as novel photosensitizing agents for photodynamic therapy (PDT). The interaction of these complexes with calf thymus DNA (CT DNA) has been explored using absorption, thermal denaturation and viscometric studies. The experimental results revealed that Co(II) and Ni(II) complexes on binding to CT DNA imply a covalent mode, most possibly involving guanine N7 nitrogen of DNA, with an intrinsic binding constant Kb of 4.5×10(4)M(-1) and 4.2×10(4)M(-1), respectively. However, interestingly, the Cu(II) complex is involved in the surface binding to minor groove via phosphate backbone of DNA double helix with an intrinsic binding constant Kb of 5.7×10(4)M(-1). The Co(II), Ni(II) and Cu(II) complexes are active in cleaving supercoiled (SC) pUC19 DNA on photoexposure to UV-visible light of 365nm, through (1)O2 generation with quantum yields of 0.28, 0.25 and 0.30, respectively. Further, these complexes are cytotoxic in A549 lung cancer cells, showing an enhancement of cytotoxicity upon light irradiation.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2013; 115C:12-21. DOI:10.1016/j.saa.2013.06.009 · 2.13 Impact Factor
  • Source
    Bioorganic & Medicinal Chemistry 04/2013; 21(7):2177. DOI:10.1016/j.bmc.2013.01.001 · 2.95 Impact Factor
  • Atanu Barik, K. Indira Priyadarsini
    [Show abstract] [Hide abstract]
    ABSTRACT: Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (Δf), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9D. Fluorescence quantum yield (ϕ(f)) and fluorescence lifetime (τ(f)) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ϕ(f) increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 12/2012; 105C:267-272. DOI:10.1016/j.saa.2012.12.036 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present investigation, a Schiff base N'(1),N'(3)-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant K(b) of 2.6×10(4)M(-1), 5.7×10(4)M(-1) and 4.5×10(4)M(-1), respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 09/2012; 101C:132-139. DOI:10.1016/j.saa.2012.09.062 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Dimethoxycurcumin (Dimc), a metabolically stable analogue of curcumin, is under investigation as an anti-tumour agent. Recently a number of studies have been performed on Dimc in this laboratory and also by others. In the present article, all these results have been summarized and wherever possible compared with those of curcumin. Rate constant for reactions of Dimc with superoxide radicals was comparable with that of curcumin, while its reaction with peroxyl radicals was much slower. These results were further supported by the observations on the scavenging of basal ROS levels in lymphocytes and evaluation of antioxidant activities. In line with the earlier reports on curcumin, Dimc was a pro-oxidant and generated ROS in tumour cells. Both curcumin and Dimc were non-toxic to lymphocytes, while exhibiting comparable cytotoxicity to tumour cells. Additionally, these compounds showed higher uptake in tumour cells than in normal lymphocytes. Fluorescence studies on both the compounds revealed their binding to genomic DNA, similar sub-cellular distribution and nuclear localization. All these studies suggested that methylation of the phenolic-OH group in curcumin, although decreasing the antioxidant activity marginally, showed comparable pro-oxidant activity, making it a promising anti-tumour agent.
    Free Radical Research 05/2011; 45(8):959-65. DOI:10.3109/10715762.2011.571681 · 2.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Studies on the antioxidant activity of two model phenols containing either an electron withdrawing (p-nitrophenol) or electron donating (p-aminophenol) group and p-hydroxyacetophenone in different solvents are reported using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay by spectrophotometry and stopped-flow techniques. The second-order rate constants measured with p-nitrophenol were found to be (1.2–5.5)×10−2 dm3 mol−1s−1 but the DPPH radical reacts much faster with p-aminophenol (k=0.5–1.1×104dm3mol−1s−1). The normal kinetic solvent effect in H atom transfer was seen in the case of p-nitrophenol with the solvent independent rate constant k o=0.1dm3mol−1s−1. The IC50 values in p-nitrophenol are similar to those measured in p-hydroxyacetophenone. On the other hand, much lower IC50 values of more than four orders of magnitude with p-aminophenol were observed. This work demonstrates that the phenol with the electron donating –NH2 substituent is a better antioxidant. KeywordsAntioxidant-DPPH-Phenols-IC50 value-Kinetic solvent effect-Stopped-flow technique
    Research on Chemical Intermediates 12/2010; 36(9):1065-1072. DOI:10.1007/s11164-010-0220-8 · 1.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three curcumin analogues viz., bisdemethoxy curcumin, monodemethoxy curcumin, and dimethoxycurcumin that differ at the phenolic substitution were synthesized. These compounds have been subjected for free radical reactions with DPPH radicals, superoxide radicals (O(2)(•-)), singlet oxygen ((1)O(2)) and peroxyl radicals (CCl(3)O(2)(•)) and the bimolecular rate constants were determined. The DPPH radical reactions were followed by stopped-flow spectrometer, (1)O(2) reactions by transient luminescence spectrometer, and CCl(3)O(2)(•) reactions using pulse radiolysis technique. The rate constants indicate that the presence of o-methoxy phenolic OH increases its reactivity with DPPH and CCl(3)O(2)(•), while for molecules lacking phenolic OH, this reaction is very sluggish. Reaction of O(2)(•-) and (1)O(2) with curcumin analogues takes place preferably at β-diketone moiety. The studies thus suggested that both phenolic OH and the β-diketone moiety of curcumin are involved in neutralizing the free radicals and their relative scavenging ability depends on the nature of the free radicals.
    Free Radical Research 11/2010; 45(3):317-25. DOI:10.3109/10715762.2010.532493 · 2.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Reactions of pulse radiolytically generated hydroxyl (()OH) radicals and one-electron specific oxidants, Br(2)(-) radicals with bergenin, a polyphenolic tannin derivative, were studied and the transients detected by absorption spectrometry. The transient absorption spectrum produced during the reaction of ()OH radicals with bergenin was broad, and pH dependent. Different modes of reactions of ()OH radicals with bergenin, viz., addition to the aromatic ring adduct and hydrogen abstraction was established by time resolved (5-400micros) transient absorption studies and also by the reaction of Br(2)(-) radicals. Comparing the transient spectra with ()OH radicals and Br(2)(-) radicals at pH 4.5 and 8.5, the absorption maximum of the phenoxyl radical was found to be at 440nm at pH 4.5 and 480nm at pH 8.5. Phenoxyl radicals are produced during ()OH radical reaction through the formation of ()OH radical adduct followed by water/OH(-) elimination. While the phenoxyl radicals of bergenin are oxidizing in nature, the hydroxyl radical adducts and the radicals produced from hydrogen abstraction are of reducing nature. The yield of the oxidizing radicals produced from the ()OH radical reaction with bergenin was determined to be 26.2% by secondary electron transfer reaction from TMPD. On the other hand the yield of reducing radicals produced from the ()OH radical reaction with bergenin was determined to be 74.1% by secondary electron transfer reaction to MV(2+). ()OH radical reactions with bergenin under oxygenated conditions and reaction with trichloro methyl peroxyl radicals with bergenin produced a new transient absorbing at 400nm, which is attributed to peroxyl type of radicals. The one-electron reduction potential for the formation of phenoxyl radical from bergenin was determined to be 0.938V versus NHE at pH 7, by electron transfer equilibrium between bergenin and chlorpromazine. The above results confirmed that reaction of ()OH radicals with bergenin, mainly produced radical adducts and one-electron oxidation accounts to only a minor process. The radical adducts may be converted to peroxyl radicals in presence of oxygen. Based on these results it can be concluded that although bergenin is a polyphenol, it may not act as a potent antioxidant, but may be act as pro-oxidant.
    Bioorganic & medicinal chemistry 07/2009; 17(16):6008-14. DOI:10.1016/j.bmc.2009.06.055 · 2.95 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Piper betel phenolics, allylpyrocatechol (APC) and chavibetol (CHV), were found to protect photosensitization-mediated lipid peroxidation (LPO) of rat liver mitochondria effectively, APC being significantly more potent. The better activity of APC vis-à-vis CHV could be attributed to its higher reactivity with (1)O(2), as revealed from the rate constant values of (1)O(2) quenching by the respective phenolics. APC also prevented the detrimental effects of the Type II photosensitization-induced toxicity to mouse fibroblast L929 cells. The results suggest that APC may play an important role in protecting biological systems against damage, by eliminating (1)O(2) generated from certain endogenous photosensitizers.
    Bioorganic & medicinal chemistry 04/2008; 16(6):2932-8. DOI:10.1016/j.bmc.2007.12.052 · 2.95 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: With an aim to develop water soluble, less toxic glutathione peroxidase (GPx) mimics, three selenocystine (SeCys) derivatives, viz., selenocystamine (SeA), diselenodipropionic acid (SeP), and methyl ester of diselenodipropionic acid (MeSeP) have been synthesized and examined for GPx activity along with SeCys. The GPx activity of the compounds was found to be in the order SeCys congruent to SeA > MeSeP > SeP. The relative affinity of these GPx mimics towards the substrates thiol and hydroperoxide were determined by Lineweaver-Burk (L-B) plots. Since the enzyme activity involves several steps of reduction and oxidation reactions, attempts have been made to understand the role of such processes in deciding the efficacy of diselenides as GPx mimics. For this, one-electron redox chemistry of these compounds was studied in aqueous solutions at pH 7 using nanosecond pulse radiolysis technique. From these studies, it was concluded that SeCys and SeA, which can undergo easy one-electron reduction, exhibit high GPx activity.
    Phosphorus Sulfur and Silicon and the Related Elements 04/2008; 183:1018–1025. DOI:10.1080/10426500801901046 · 0.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 3,3'-diselenodipropionic acid (DSePA), a derivative of selenocystine, has been synthesized and examined for antioxidant activity, glutathione peroxidase (GPx) activity, and cytotoxicity. The effect of DSePA on membrane lipid peroxidation, release of hemoglobin, and intracellular K+ ion as a consequence of erythrocyte (red blood cells or RBCs) oxidation by free radicals generated by 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) were used to evaluate the antioxidant ability. Lipid peroxidation, hemolysis, and K+ ion loss in RBCs were assessed, respectively, by formation of thiobarbituric acid reactive substances (TBARS), absorbance of hemoglobin at 532 nm and flame photometry. The IC50 values for lipid peroxidation, hemolysis, and K+ ion leakage were 45+/-5, 20+/-2, and 75+/-8 microM, respectively. DSePA treatment prevented the depletion of glutathione (GSH) levels in RBCs from free-radical-induced stress. DSePA is a good peroxyl radical scavenger and the bimolecular rate constant for the reaction of DSePA with a model peroxyl radical, trichloromethyl peroxyl radical (CCl 3O2*), was determined to be 2.7x10(8) M(-1) s(-1) using a pulse radiolysis technique. DSePA shows GPx activity with higher substrate specificity towards peroxides than thiols. The cytotoxicity of DSePA was studied in lymphocytes and EL4 tumor cells and the results showed that DSePA is nontoxic to these cells at the concentrations employed. These results when compared with two well-known selenium compounds, sodium selenite and ebselen, indicated that DSePA, although it shows lesser GPx activity, has higher free radical scavenging ability and lesser toxicity.
    Chemical Research in Toxicology 11/2007; 20(10):1482-7. DOI:10.1021/tx700137a · 4.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of mononuclear copper (II) complex of curcumin in 1:1 stoichiometry (hereafter referred to as complex) administered 30 min before gamma-irradiation (4.5 Gy) on alterations in antioxidant and Thiobarbituric acid reactive substances (TBARS) levels in livers was studied in comparison to curcumin at a dose of 50 mg/kg. The different antioxidants like GSH, GST, catalase, SOD, TBARS and total thiols were estimated in the liver homogenates excised at different time intervals (1, 2 and 4 h) post irradiation using colorimetric methods. There was a radiation-induced decrease in the levels of all the studied enzymes at 1 h post irradiation, while an increase was observed at later time points. Both curcumin and complex treatment in sham-irradiated mice decreased the levels of GSH and total thiols, whereas there was an increase in the levels of catalase, GST and SOD compared to normal control. Under the influence of irradiation, both curcumin and complex treatment protected the decline in the levels of GSH, GST, SOD, catalase and total thiols, and inhibited radiation-induced lipid peroxidation. Further, the complex was found to be more effective in protecting the enzymes at 1 h post irradiation compared to curcumin treated group. This may be due to the higher rate constants of the complex compared to curcumin for their reactions with various free radicals.
    Journal of Radiation Research 06/2007; 48(3):241-5. DOI:10.1269/jrr.06103 · 1.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two stoichiometrically different copper(II) complexes of curcumin (stoichiometry, 1:1 and 1:2 for copper:curcumin), were examined for their superoxide dismutase (SOD) activity, free radical-scavenging ability and antioxidant potential. Both the complexes are soluble in lipids and DMSO. The formation constants of the complexes were determined by voltammetry. EPR spectra of the complexes in DMSO at 77K showed that the 1:2 Cu(II)-curcumin complex is square planar and the 1:1 Cu(II)-curcumin complex is distorted orthorhombic. Cu(II)-curcumin complex (1:1) with larger distortion from square planar structure shows higher SOD activity. These complexes inhibit gamma-radiation induced lipid peroxidation in liposomes and react with DPPH acting as free radical scavengers. One-electron oxidation of the two complexes by radiolytically generated azide radicals in Tx-100 micellar solutions produced phenoxyl radicals, indicating that the phenolic moiety of curcumin in the complexes participates in free radical reactions. Depending on the structure, these two complexes possess different SOD activities, free radical neutralizing abilities and antioxidant potentials. In addition, quantum chemical calculations with density functional theory have been performed to support the experimental observations.
    European Journal of Medicinal Chemistry 05/2007; 42(4):431-9. DOI:10.1016/j.ejmech.2006.11.012 · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Binding of curcumin, an antioxidant and anti-tumor agent to human serum albumin (HSA) has been investigated by following absorption and fluorescence spectral changes in HSA and curcumin. From the temperature dependent fluorescence changes and kinetic measurements using stopped-flow spectrometer, enthalpy and entropy changes and activation energy for the binding of curcumin to HSA were evaluated. Following fluorescence resonance energy transfer (FRET) between excited tryptophan in HSA and HSA bound curcumin, the critical transfer distance and mean distance between tryptophan-214 in HSA and curcumin were estimated. Effect of chemical and thermal denaturation of HSA on curcumin fluorescence was also studied. (c) 2007 Elsevier B.V. All rights reserved.
    Chemical Physics Letters 02/2007; 436(1-3):239-243. DOI:10.1016/j.cplett.2007.01.006 · 1.99 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Treatment of phenols with ninhydrin in acidic medium afforded 2-hydroxy-2-(ortho-hydroxy-phenyl/naphthyl)-1,3-dioxoindanes, which being unstable were isolated in their hemiketal forms. These synthesized compounds were subjected to TLC screening for radical scavenging and in vitro lipoxgenase and cycloxygenase enzyme inhibition assays. The best compound was identified and studied in detail for steady-state and time-resolved free radical kinetics, viz., DPPH, ABTS(-), *OH and rate constants for these reactions were evaluated. The best compound was also subjected to in vivo anti-inflammatory and analgesic activities in which the compound showed good promise for further structural optimization.
    Bioorganic & Medicinal Chemistry 12/2006; 14(21):7113-20. DOI:10.1016/j.bmc.2006.06.068 · 2.95 Impact Factor

Publication Stats

632 Citations
66.41 Total Impact Points


  • 2003–2015
    • Bhabha Atomic Research Centre
      • • Radiation & Photochemistry Division
      • • Bio-Organic Division
      • • Radiation Biology and Health Sciences Division
      • • Radiation Chemistry & Chemical Dynamics Division
      Mumbai, Maharashtra, India