Design, synthesis and biological evaluation of a novel series of anthrapyrazoles linked with netropsin-like oligopyrrole carboxamides as anticancer agents

Abstract

Anticancer drugs that bind to DNA and inhibit DNA-processing enzymes represent an important class of anticancer drugs. Combilexin molecules, which combine DNA minor groove binding and intercalating functionalities, have the potential for increased DNA binding affinity and increased selectivity due to their dual mode of DNA binding. This study describes the synthesis of DNA minor groove binder netropsin analogs containing either one or two N-methylpyrrole carboxamide groups linked to DNA-intercalating anthrapyrazoles. Those hybrid molecules which had both two N-methylpyrrole groups and terminal (dimethylamino)alkyl side chains displayed submicromolar cytotoxicity towards K562 human leukemia cells. The combilexins were also evaluated for DNA binding by measuring the increase in DNA melting temperature, for DNA topoisomerase IIα-mediated double strand cleavage of DNA, for inhibition of DNA topoisomerase IIα decatenation activity, and for inhibition of DNA topoisomerase I relaxation of DNA. Several of the compounds stabilized the DNA-topoisomerase IIα covalent complex indicating that they acted as topoisomerase IIα poisons. Some of the combilexins had higher affinity for DNA than their parent anthrapyrazoles. In conclusion, a novel group of compounds combining DNA intercalating anthrapyrazole groups and minor groove binding netropsin analogs have been designed, synthesized and biologically evaluated as possible novel anticancer agents.

Design, synthesis, and biological evaluation of a novel series of bisintercalating DNA-binding piperazine-linked bisanthrapyrazole compounds as anticancer agents

“…21,22 The ability of 20 M of the compounds to inhibit the decatenation of concatenated kDNA by topoisomerase II was determined as previously described. 6,23 Densitometry of the fully decatenated open circular DNA bands in the gel image of Fig. 3A was used to calculate the percentage inhibition data of Table 1.…”

“…Stabilization of the covalent complex leads to double strand DNA breaks that are toxic to the cell. Thus, DNA cleavage assay experiments, 26 as we previously described 3-6,27 were carried out to see whether 50 M of the compounds stabilized the cleavable complex using etoposide as a positive control. As shown in Fig.…”

“…More recently, we reported the synthesis and biological evaluation of monointercalating anthrapyrazole combilexins with DNA minor groove binding netropsin-like oligopyrrole carboxamide side chains. 6 In principle, bisintercalating molecules should be able to interact more strongly with DNA and thus should have a prolonged residence time on DNA allowing them to interfere with DNA processing enzymes. 7-10 Bisintercalators should also, in principle, have enhanced DNA sequence specificity compared to monointercalators or minor groove binders.…”

Mechanisms of Action and Reduced Cardiotoxicity of Pixantrone; a Topoisomerase II Targeting Agent with Cellular Selectivity for the Topoisomerase II Isoform

“…Compounds that either intercalate into or bind in the minor groove of DNA stabilize the DNA double helix and increase the temperature at which the DNA denatures or unwinds (McGhee, 1976;Priebe et al, 2001;Zhang et al, 2011). The effect of pixantrone and doxorubicin on the melting temperature (DT m ) of sonicated calf thymus DNA (6 mg/ml or 9.5 mM in base pairs) was measured in 10 mM Tris-HCl buffer (pH 7.4) in a Cary 1 (Varian, Mississauga, Canada) double-beam spectrophotometer by measuring the absorbance increase at 260 nm upon the application of a temperature ramp of 1°C/min, as we previously described (Zhang et al, 2010(Zhang et al, , 2011. The maximum of the first derivative of the absorbance-temperature curve was used to obtain the T m .…”

Structure-based design, synthesis and biological testing of etoposide analog epipodophyllotoxin–N-mustard hybrid compounds designed to covalently bind to topoisomerase II and DNA

“…The spectrophotometric 96-well plate cell growth inhibition MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H–tetrazolium) CellTiter 96 AQueous One Solution Cell Proliferation assay (Promega, Madison, WI), which measures the ability of the cells to enzymatically reduce MTS after drug treatment, has been described. 29,49 The drugs were dissolved in DMSO and the final concentration of DMSO did not exceed an amount (typically 0.4 % or less) that had any detectable effect on cell growth. The cells were incubated with the drugs for 72 h and then assayed with MTS.…”