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Bera, Pradip and Brandão, Paula and Mondal, Gopinath and Santra, Ananyakumari and Jana, Abhimanyu and Mokhamatam, R.B. and Manna, S.K. and Mandal, T.K. and Bera, Pulakesh (2019) An unusual iminoacylation of 2-amino pyridyl thiazole: Synthesis, X-ray crystallography and DFT study of copper(II) amidine complexes and their cytotoxicity, DNA binding and cleavage study. Polyhedron, 159. pp. 436-445. ISSN 0277-5387

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Insertion of acetonitrile in the exocyclic NH2 group of the thiazole unit of 2-amino-4-(2-pyridyl)thiazole (HL) in the presence of copper chloride results in the formation of the monomeric amidine complex [Cu{LC(Me)=NH)}Cl2] (1). The same reaction of HL and copper(II) perchlorate yields the complex [Cu(HL)2](ClO4)2 (2), without acetonitrile insertion. However, the presence of a spacer donor, e.g. pyrazine, in the reaction medium results in the formation of a dinuclear amidine derivative, [(ClO4){LC(Me)=NH}Cu(μ-pyrazine)Cu{LC(Me)=NH}(ClO4)] (ClO4)2 (3). Complexes 1 and 3 are the first examples of copper assisted iminoacylation of 2-amino pyridylthiazole derivatives, confirming a nitrile to amidine transformation. The new complexes were characterized by single crystal X-ray crystallography, cyclic voltammetry and a DFT study. The complexes have a potential cytotoxic effect in human monocytic cells (U937) with IC50 values ranging from 0.84 to 4.5 μM. Significant necrotic activities are ascertained by a lactate dehydrogenase (LDH) enzyme release assay. The interaction with calf thymus (CT) DNA shows the binding constant (Kb) values are ∼ 104 M−1. The chemical nuclease activity of 1, 2 and 3 result in 65, 99 and 80% relaxation of supercoiled DNA at 10 μM in the presence of glutathione (GSH, 1 mM), respectively. The study with radical scavengers proved that a hydroxyl or singlet oxygen-like species is responsible for the DNA degradation.

Item Type: Article
Depositing User: Dr P Divakar
Date Deposited: 28 Dec 2018 07:00
Last Modified: 22 Jan 2019 05:36
URI: http://cdfd.sciencecentral.in/id/eprint/875

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