Spectroscopic, computational and electrochemical studies on the formation of the copper complex of 1-amino-4-hydroxy-9,10-anthraquinone and effect of it on superoxide formation by NADH dehydrogenase

Abstract

A 1 : 2 copper(II) complex of 1-amino-4-hydroxy-9,10-anthraquinone (QH) having the molecular formula CuQ2 was prepared and characterized by elemental analysis, NMR, FTIR, UV-vis and mass spectroscopy. The powder diffraction of the solid complex, magnetic susceptibility and ESR spectra were also recorded. The presence of the planar anthraquinone moiety in the complex makes it extremely difficult to obtain a single crystal suitable for X-ray diffraction studies. To overcome this problem, density functional theory (DFT) was used to evaluate an optimized structure of CuQ2. In the optimized structure, it was found that there is a tilt of the two planar aromatic anthraquinone rings of the complex with respect to each other in the two planes containing the O-Cu(II)-O plane. The present study is an important addition to the understanding of the structural aspects of metal-anthracyclines because there are only a few reports on the actual structures of metal-anthracyclines. The theoretical vibrational spectrum of the complex was assigned with the help of vibrational energy distribution analysis (VEDA) using potential energy distribution (PED) and compared with experimental results. Being important in producing the biochemical action of this class of molecules, the electrochemical behavior of the complex was studied in aqueous and non-aqueous solvents to find certain electrochemical parameters. In aqueous media, reduction involves a kinetic effect during electron transfer at an electrode surface, which was characterized very carefully using cyclic voltammetry. Electrochemical studies showed a significant modification in the electrochemical properties of 1-amino-4-hydroxy-9,10-anthraquinone (QH) when bound to Cu(II) in the complex compared to those observed for free QH. This suggests that the copper complex might be a good choice as a biologically active molecule, which was reflected in the lack of stimulated superoxide generation by the complex.

Influence of ionic strength on the interaction of THA and its Cu(ii) complex with DNA helps to explain studies on various breast cancer cells

“…[31][32][33][34][35][36][37] All experiments were repeated three times. Voltammograms were recorded using the three-electrode system; a glassy-carbon electrode of surface area 0.1256 cm 2 served as the working electrode, Ag/AgCl, KCl (saturated) was the reference while a platinum wire served as counter electrode.…”

“…[22][23][24][25][26] Avoiding anthracyclines could be an immediate approach to remove the side effects, but that implies doing away with an effective group of chemotherapeutic agents. [30][31][32][33][34][35][36][37] A Cu II complex of purpurin for example, whose crystal structure we reported recently is an inhibitor of human DNA topoisomerase enzymes resembling doxorubicin (DOX). Hence, there is a need to broaden the activity spectrum choosing molecules that are simple, addressing several related issues.…”

Synthesis, crystal structure from PXRD of a MnII(purp)2complex, interaction with DNA at different temperatures and pH and lack of stimulated ROS formation by the complex

“…[6][7][8] Studies reveal it is also responsible for inhibiting the activity of topoisomerase enzymes. [10][11][12][13][14][15] Findings indicate while for the first two aspects there was not much difference whether the hydroxy-9,10-anthraquinone was on its own or within an anthracycline antibiotic, for the remaining the difference was significant. [10][11][12][13][14][15] Findings indicate while for the first two aspects there was not much difference whether the hydroxy-9,10-anthraquinone was on its own or within an anthracycline antibiotic, for the remaining the difference was significant.…”

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The formation of reactive oxygen species (ROS) by anthracycline anticancer drugs is essential for its antitumor activity but they also make these drugs cardiotoxic. 12,14,15,[20][21][22][23] Purpurin (1, 2, 4 trihydroxy-9,10-anthraquinone) resembling the core of anthracyclinesThe novel aspects of this study are the structure of the complex obtained from powder X-ray diffraction data since single crystals were not obtained, determination of thermodynamic parameters pertaining to interaction of purpurin and its complex with calf thymus DNA and lack of stimulated ROS formation by the complex. Interestingly, inspite of producing fewer ROS, some of the complexes are effective antitumor agents, often better than the parent anthracycline.

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CuIIcomplex of emodin with improved anticancer activity as demonstrated by its performance on HeLa and Hep G2 cells

“…The results were analyzed using eqn (S1)-(S5), ESI. † [16][17][18][19][20][29][30][31][32][33] 2.4.2 At different temperatures for evaluation of the thermodynamic parameters. Titration of the compounds with DNA was performed at four different temperatures at a constant pH ($7.87) and ionic strength of the medium.…”