Articles written in Journal of Chemical Sciences
Volume 131 Issue 2 February 2019 Article ID 0009
Several amino acid-based photo-active monomeric iron(III) complexes of the general formula,[Fe(L)2]PP-, where L= Schiff base ligands (salisalidene arginine, salicylidenetryptophan, 3,5-di-tert-butyl benzalidine arginine and salicylidene tryptophan) were synthesized, characterized and explored for photoactivated anticancer activity to Chang Liver Cells, HeLa and MCF-7 cells. Complexes exhibited remarkable photo-cytotoxicity with IC50 value to the extent of 0.7 μM to Chang Liver Cells in visible light and there wasa 40-fold enhancement in cytotoxicity in comparison to the cytotoxicity in dark. Complexes were non-toxic to MCF-10A (normal cells) in dark and visible light (IC50 > 100 μM in dark; IC50 > 80 μM in visible light) signifying target-specific nature of the anti-tumour activity of the complexes. Increased ROS concentration,as probed by DCFDA assay, in the cancer cells was responsible for apoptotic cell death. Decarboxylation or phenolate-Fe(III) charge transfer of photo-activated iron(III) complexes generating • OH radicals (ROS) were responsible for the apoptosis. Overall, the tumour-selective photo-activated anticancer activity of the amino acidbased iron(III) complexes have shown a promising aspect in developing iron-based photo-chemotherapeutics as the next generation PDT agents.
Volume 131 Issue 2 February 2019 Article ID 0017
Volume 132 All articles Published: 15 February 2020 Article ID 0043
Temperature-driven, highly sensitive and selective ''TURN-ON'' fluorometric detection of Zn2+ by benzothiazole-based probes (L1 and L2) was reported in physiological pH in the present work. Iron(II) acted as the reversible switch or trigger for the reversible detection of Zn2+ ions by the probes resulting in
''TURN-OFF'' fluorescence at room temperature. However, selective detection of Zn2+ in the presence of Fe2+ was irreversible at 0–5 °C. Such temperature dependence on reversible fluorometric detection of Zn2+ in the presence of Fe2+ was explained from the thermodynamic perspective as well as DFT calculations inwhich the absolute enthalpy (H) and Gibbs free energy (G) of the resultant complexes and the fluorophores (L1 and L22) at different temperatures were determined. Enhanced fluorescence of the Zn2+ bound probes wasdue to the inhibition of excited-state intramolecular proton transfer (ESIPT). Effect of solvents, pH, and temperature on the fluorometric detection of Zn2+ was also probed in the present work. The results were translated into the visual detection of Zn2+ on paper-based fluorescence probe and later we demonstrated thesensing of mobile Zn2+ ions by the probes in living HeLa cells as the proof of concept of our present investigations
Volume 133 All articles Published: 21 April 2021 Article ID 0042
Four new ternary Oxovanadium(IV) complexes, [VO(L)(B1-4)](acac), where, L = (E)-2- (2-hydroxybenzylideneamino)-5-guanidinopentanoic acid (Argininesalisylidene) and B were 1H-imidazo-[4,5-f][1,10]-phenanthroline (B1) (1), 2-phenyl-1H-imidazo [4,5-f][1,10] phenanthroline (B2) (2), 2-(naphthalen-1-yl)-1H-imidazo [4,5-f][1,10] phenanthroline (B3) (3) or 1-(pyren-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline(B4) (4) were synthesized, characterized and photocytotoxicity in A549 cell were studied in dark andvisible light (400–700 nm, 10 J cm-2). Photochemistry of the complexes (1-4) related to the generation of singlet oxygen (1O2) was studied in detail. The presence of triplet excited state in the complexes was probedfrom perylene assay. Photo-activated generation of singlet oxygen from the complexes was probed by DPBF assay and the degree of photo-cytotoxicity of the complexes was related to their ability in photo-activated 1O2 generation. Complexes 4 exhibited remarkable photocytotoxicity in A549 cells with photo index (PI) ~ 16 invisible light (400–700 nm, 10 J cm-2) (IC50, 3.81 lμM), while complexes were almost less-toxic in dark (IC50,59.7 lμM). Intracellular ROS generation was studied from 2Ꞌ,7Ꞌ-dichlorofluorescein diacetate (DCFH-DA).Annexin V-FITC/PI assay suggested apoptotic nature of cell death. Overall, the remarkable photocytotoxicefficacy of the new Oxovanadium(IV) complexes (1-4) making them the potential photochemotherapeutic agents in lieu of porphyrin-based PDT agents.
Volume 133, 2021
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