Abstract
In this paper, Cu(II), Mn(II) and Zn(II) complexes with N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride (HL1Cl) were synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis and DFT calculations. In all three complexes, a ligand (L1) is coordinated in a deprotonated formally neutral zwitterionic form via NNO donor set atoms. Cu(II) and Zn(II) form mononuclear penta-coordinated complexes [CuL1(N3)(CH3OH)]BF4 and [ZnL1(N3)2], respectively, while Mn(II) forms a binuclear [Mn2L12(μ-1,1-N3)2(N3)2]·2CH3OH complex, with unusual distorted trigonal-prismatic geometry around the metal centers. The antimicrobial activity of these complexes was tested against a panel of Gram-negative and Gram-positive bacteria, two yeasts and one fungal strain. The binuclear Mn(II) complex showed antifungal activity of similar intensity to amphotericin B. Based on the results of the brine shrimp test and DPPH radical scavenging activity, the most active Cu(II) and Mn(II) complexes were selected for evaluation of cytotoxic activity against five malignant cancer cell lines (HeLa, A375, MCF7, PC-3 and A549) and one normal cell line HaCaT. Both complexes showed significant activity. It should be pointed out that the activity of the Mn(II) complex against the MCF7 breast cancer cell line is only slightly weaker than that of cisplatin, but with selectivity to the tumor cell line in comparison to normal HaCaT cells, which is non-existent in the case of cisplatin.
Highlights
Metal complexes with hydrazones have been investigated intensively during previous years due to their various pharmaceutical applications as antitumor, antibacterial, antiviral and antifungal agents.[1]
Cu(II) and Mn(II) complexes have been studied as low molecular weight model compounds that mimic the active site of superoxide dismutase (SOD),[6,7] which participate in cell oxidative stress regulation
The reaction of 2-acetylthiazole and Girard’s T reagent was performed according to the previously reported method[30] which yielded the ligand N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl) ethylidene)hydrazinyl)ethan-1-aminium chloride (HL1Cl) that was used for the synthesis of complexes 1–3 (Scheme 1)
Summary
Manganese and zinc are essential trace elements with many physiological functions. Ions of these elements act as cofactors and as allosteric components for many enzymes.[3,4,5] Cu(II) and Mn(II) complexes have been studied as low molecular weight model compounds that mimic the active site of superoxide dismutase (SOD),[6,7] which participate in cell oxidative stress regulation. Complexes of Cu(II), Mn(II) and Zn(II) with Schiff base ligands can possess different biological activities, such as effective inhibition against bacteria[8,9,10,11,12,13,14,15] and fungi,[8,9,11,13,14] as well as cytotoxic activity.[8,16,17,18]. In continuation of our previous investigations on the synthesis, characterization and biological activity of complexes with Girard’s T reagent-based hydrazones,[6,25,26,27,28,29] which showed moderate biological activities, in this paper, three novel Girard’s T reagent–based complexes with Cu(II), Mn(II) and Zn (II) ions are described
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