The Binding of a Hydroxy‐9,10‐anthraquinone Cu^II Complex to Calf Thymus DNA: Electrochemistry and UV/Vis Spectroscopy

Abstract

Anthracyclines are broad‐spectrum antibiotics that are used against several human cancers. Hydroxy‐9,10‐anthraquinone compounds closely resemble anthracycline antibiotics from a structural and functional viewpoint. High cost and aspects of toxicity introduce limitations on its use. On complex formation the toxicities of anthracyclines decrease. A close analogue is sodium 1,4‐dihydroxy‐9,10‐anthraquinone‐2‐sulphonate (AS), which is a comparatively cheaper molecule and resembles a good number of anthracycline derivatives. It forms a complex with CuII, [Cu(AS)2]. The complex interacts with calf thymus DNA that was studied by UV/Vis spectroscopy and cyclic voltammetry. The experimental data obtained from the two techniques was analyzed for binding constant and size of the binding site. These results not only corroborate each other but also justify earlier data obtained using fluorescence spectroscopy. An important aspect to this study was that nonlinear curve fitting, which is usually applied for analyzing DNA interaction using fluorescence and absorption spectroscopy, was used for the first time to analyze the interaction of the complex with DNA using cyclic voltammetry by monitoring the change in the reduction peak current (Ip). The DNA binding data provides an insight into a probable mode of action of the hydroxy‐9,10‐anthraquinones within cells as modification of DNA that leads to cell death is an important aspect in cancer research.

Design, Synthesis and in vitro Anticancer Activity of a Cu(II) Complex of Carminic Acid: A Novel Small Molecule Inhibitor of Human DNA Topoisomerase I and Topoisomerase II

“…Binding constant values determined earlier for different hydroxy‐9,10‐anthraquinones with DNA show they are an order lower than anthracyclines . In this study, although overall binding constant values for CA with c t DNA was still lower than anthracyclines, it was higher than several hydroxy‐9,10‐anthraquinones studied earlier .…”

“…Comparing some of the previous studies on hydroxy‐9,10‐anthraquinones with those of the anthracycline drugs with regard to physicochemical properties, electrochemical behavior, biophysical interactions and the action of the compounds on different cancer cells reveal although physicochemical and electrochemical properties are strikingly similar, interaction with DNA was almost always weaker than that observed for anthracyclines . DNA interaction being crucial for drug action, Carminic acid (CA), having an α‐D‐glucopyranosyl unit attached to a hydroxy‐9,10‐anthraquinone was chosen for this study . This helped us to realize the role of sugar units in anthracyclines as well .…”

A study on the formation of the nitro radical anion by ornidazole and its significant decrease in a structurally characterized binuclear Cu(II)-complex: impact in biology

“…Hence, we chose to study the interaction of Onz and [Cu 2 (OAc) 4 (Onz) 2 ] using cyclic voltammetry so that the reduction of the nitro group could be monitored. 17,32,44 The change in ΔI was put into standard equations (ESI † section) to yield values for binding constants and the site size of interaction. 6,7,17,28,43 The change in response of the nitro radical anion was followed to understand the interaction of the compounds with ctDNA.…”

“…17,28,43 The interaction of nitroimidazoles with DNA that proceeds via formation of the nitro radical anion can only be properly detected if the interaction is monitored by cyclic voltammetry. 17,32,44 750 μL of 1000 μM Onz or [Cu 2 (OAc) 4 (Onz) 2 ] along with 600 μL of 100 mM Tris buffer and 720 μL of 500 mM NaCl was taken in an electrochemical cell. 7,17,43 Experiments were performed at a scan rate of 100 mV s −1 .…”

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

“…[39][40][41][42] The titration data from cyclic voltammetry was fitted to Eq. 10 and 11 provide values for K d (= 1/K app ) using non-linear curve fit analysis.…”