Interaction of 3,9-disubstituted acridine with single stranded poly(rA), double stranded poly(rAU) and triple stranded poly(rUAU): molecular docking - A spectroscopic tandem study.

RNA plays an important role in many biological processes which are crucial for cell survival, and it has been suggested that it may be possible to inhibit individual processes involved in many diseases by targeting specific sequences of RNA. The aim of this work is to determine the affinity of novel 3,9-disubstited acridine derivative 1 with three different RNA molecules, namely single stranded poly(rA), double stranded homopolymer poly(rAU) and triple stranded poly(rUAU). The results of the absorption titration assays show that the binding constant of the novel derivative to the RNA molecules was in the range of 1.7-6.2 × 104 mol dm-3. The fluorescence and circular dichroism titration assays revealed considerable changes. The most significant results in terms of interpreting the nature of the interactions were the melting temperatures of the RNA samples in complexes with the 1. In the case of poly(rA), denaturation resulted in a self-structure formation; increased stabilization was observed for poly(rAU), while the melting points of the ligand-poly(rUAU) complex showed significant destabilization as a result of the interaction. The principles of molecular mechanics were applied to propose the non-bonded interactions within the binding complex, pentariboadenylic acid and acridine ligand as the study model. Initial molecular docking provided the input structure for advanced simulation techniques. Molecular dynamics simulation and cluster analysis reveal π - π stacking and the hydrogen bonds formation as the main forces that can stabilize the binding complex. Subsequent MM-GBSA calculations showed negative binding enthalpy accompanied the complex formation and proposed the most preferred conformation of the interaction complex.

Chili pepper extracts, capsaicin, and dihydrocapsaicin as potential anticancer agents targeting topoisomerases.

DNA topoisomerases regulate conformational changes in DNA topology during normal cell growth, such as replication, transcription, recombination, and repair, and may be targeted for anticancer drugs. A DNA topology assay was used to investigate DNA-damaging/protective activities of extracts from Habanero Red (HR), Habanero Maya Red (HMR), Trinidad Moruga Scorpion (TMS), Jalapeno (J), Serrano pepper (SP), Habanero Red Savina (HRS), Bhut Jolokia (BJ), and Jamaica Rosso (JR) peppers, demonstrating their inhibitory effect on the relaxation of pBR by Topo I. DNA topoisomerase II (Topo II) is proven therapeutic target of anticancer drugs. Complete inhibition of Topo II was observed for samples TMS, HR, and HMR. Extracts J and SP had the lowest capsaicin and dihydrocapsaicin content compared to other peppers. HR, HMR, TMS, J, S, HRS, BJ, JR extracts showed the anticancer effect, examined by MTS and xCell assay on the in vitro culture of human colon carcinoma cell line HCT116.

Novel 3,9-Disubstituted Acridines with Strong Inhibition Activity against Topoisomerase I: Synthesis, Biological Evaluation and Molecular Docking Study.

A series of novel 3,9-disubstituted acridines were synthesized and their biological potential was investigated. The synthetic plan consists of eight reaction steps, which produce the final products, derivatives 17a-17j, in a moderate yield. The principles of cheminformatics and computational chemistry were applied in order to study the relationship between the physicochemical properties of the 3,9-disubstituted acridines and their biological activity at a cellular and molecular level. The selected 3,9-disubstituted acridine derivatives were studied in the presence of DNA using spectroscopic (UV-Vis, circular dichroism, and thermal denaturation) and electrophoretic (nuclease activity, relaxation and unwinding assays for topoisomerase I and decatenation assay for topoisomerase IIα) methods. Binding constants (2.81-9.03 × 104 M-1) were calculated for the derivatives from the results of the absorption titration spectra. The derivatives were found to have caused the inhibition of both topoisomerase I and topoisomerase IIα. Molecular docking simulations suggested a different way in which the acridines 17a-17j can interact with topoisomerase I versus topoisomerase IIα. A strong correlation between the lipophilicity of the derivatives and their ability to stabilize the intercalation complex was identified for all of the studied agents. Acridines 17a-17j were also subjected to in vitro screening conducted by the Developmental Therapeutic Program of the National Cancer Institute (NCI) against a panel of 60 cancer cell lines. The strongest biological activity was displayed by aniline acridine 17a (MCF7-GI50 18.6 nM) and N,N-dimethylaniline acridine 17b (SR-GI50 38.0 nM). The relationship between the cytostatic activity of the most active substances (derivatives 17a, 17b, and 17e-17h) and their values of KB, LogP, ΔS°, and δ was also investigated. Due to the fact that a significant correlation was only found in the case of charge density, δ, it is possible to assume that the cytostatic effect might be dependent upon the structural specificity of the acridine derivatives.

Acridine Based N-Acylhydrazone Derivatives as Potential Anticancer Agents: Synthesis, Characterization and ctDNA/HSA Spectroscopic Binding Properties.

A series of novel acridine N-acylhydrazone derivatives have been synthesized as potential topoisomerase I/II inhibitors, and their binding (calf thymus DNA­ctDNA and human serum albumin­HSA) and biological activities as potential anticancer agents on proliferation of A549 and CCD-18Co have been evaluated. The acridine-DNA complex 3b (-F) displayed the highest Kb value (Kb = 3.18 × 103 M−1). The HSA-derivatives interactions were studied by fluorescence quenching spectra. This method was used for the calculation of characteristic binding parameters. In the presence of warfarin, the binding constant values were found to decrease (KSV = 2.26 M−1, Kb = 2.54 M−1), suggesting that derivative 3a could bind to HSA at Sudlow site I. The effect of tested derivatives on metabolic activity of A549 cells evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide or MTT assay decreased as follows 3b(-F) > 3a(-H) > 3c(-Cl) > 3d(-Br). The derivatives 3c and 3d in vitro act as potential dual inhibitors of hTopo I and II with a partial effect on the metabolic activity of cancer cells A594. The acridine-benzohydrazides 3a and 3c reduced the clonogenic ability of A549 cells by 72% or 74%, respectively. The general results of the study suggest that the novel compounds show potential for future development as anticancer agents.

Acridine derivatives as inhibitors/poisons of topoisomerase II.

The potential of acridines (amsacrine) as a topoisomerase II inhibitor or poison was first discovered in 1984, and since then, a considerable number of acridine derivatives have been tested as topoisomerase inhibitors/poisons, containing different substituents on the acridine chromophore. This review will discuss a series of studies published over the course of the last decade, which have investigated various novel acridine derivatives against topoisomerase II activity.

Synthesis of Novel Biologically Active Proflavine Ureas Designed on the Basis of Predicted Entropy Changes.

A novel series of proflavine ureas, derivatives 11a-11i, were synthesized on the basis of molecular modeling design studies. The structure of the novel ureas was obtained from the pharmacological model, the parameters of which were determined from studies of the structure-activity relationship of previously prepared proflavine ureas bearing n-alkyl chains. The lipophilicity (LogP) and the changes in the standard entropy (ΔS°) of the urea models, the input parameters of the pharmacological model, were determined using quantum mechanics and cheminformatics. The anticancer activity of the synthesized derivatives was evaluated against NCI-60 human cancer cell lines. The urea derivatives azepyl 11b, phenyl 11c and phenylethyl 11f displayed the highest levels of anticancer activity, although the results were only a slight improvement over the hexyl urea, derivative 11j, which was reported in a previous publication. Several of the novel urea derivatives displayed GI50 values against the HCT-116 cancer cell line, which suggest the cytostatic effect of the compounds azepyl 11b-0.44 µM, phenyl 11c-0.23 µM, phenylethyl 11f-0.35 µM and hexyl 11j-0.36 µM. In contrast, the novel urea derivatives 11b, 11c and 11f exhibited levels of cytotoxicity three orders of magnitude lower than that of hexyl urea 11j or amsacrine.

Synthesis of New Biscoumarin Derivatives, In Vitro Cholinesterase Inhibition, Molecular Modelling and Antiproliferative Effect in A549 Human Lung Carcinoma Cells.

A series of novel C4-C7-tethered biscoumarin derivatives (12a-e) linked through piperazine moiety was designed, synthesized, and evaluated biological/therapeutic potential. Biscoumarin 12d was found to be the most effective inhibitor of both acetylcholinesterase (AChE, IC50 = 6.30 µM) and butyrylcholinesterase (BChE, IC50 = 49 µM). Detailed molecular modelling studies compared the accommodation of ensaculin (well-established coumarin derivative tested in phase I of clinical trials) and 12d in the human recombinant AChE (hAChE) active site. The ability of novel compounds to cross the blood-brain barrier (BBB) was predicted with a positive outcome for compound 12e. The antiproliferative effects of newly synthesized biscoumarin derivatives were tested in vitro on human lung carcinoma cell line (A549) and normal colon fibroblast cell line (CCD-18Co). The effect of derivatives on cell proliferation was evaluated by MTT assay, quantification of cell numbers and viability, colony-forming assay, analysis of cell cycle distribution and mitotic activity. Intracellular localization of used derivatives in A549 cells was confirmed by confocal microscopy. Derivatives 12d and 12e showed significant antiproliferative activity in A549 cancer cells without a significant effect on normal CCD-18Co cells. The inhibition of hAChE/human recombinant BChE (hBChE), the antiproliferative activity on cancer cells, and the ability to cross the BBB suggest the high potential of biscoumarin derivatives. Beside the treatment of cancer, 12e might be applicable against disorders such as schizophrenia, and 12d could serve future development as therapeutic agents in the prevention and/or treatment of Alzheimer's disease.

Tacrine-Coumarin Derivatives as Topoisomerase Inhibitors with Antitumor Effects on A549 Human Lung Carcinoma Cancer Cell Lines.

A549 human lung carcinoma cell lines were treated with a series of new drugs with both tacrine and coumarin pharmacophores (derivatives 1a-2c) in order to test the compounds' ability to inhibit both cancer cell growth and topoisomerase I and II activity. The ability of human topoisomerase I (hTOPI) and II to relax supercoiled plasmid DNA in the presence of various concentrations of the tacrine-coumarin hybrid molecules was studied with agarose gel electrophoresis. The biological activities of the derivatives were studied using MTT assays, clonogenic assays, cell cycle analysis and quantification of cell number and viability. The content and localization of the derivatives in the cells were analysed using flow cytometry and confocal microscopy. All of the studied compounds were found to have inhibited topoisomerase I activity completely. The effect of the tacrine-coumarin hybrid compounds on cancer cells is likely to be dependent on the length of the chain between the tacrine and coumarin moieties (1c, 1d = tacrine-(CH2)8-9-coumarin). The most active of the tested compounds, derivatives 1c and 1d, both display longer chains.

A new look at 9-substituted acridines with various biological activities.

Heterocycles have long been the focus of intensive study in attempts to develop novel therapeutic compounds, and acridine, a polynuclear nitrogen molecule containing a heterocycle, has attracted a considerable amount of scientific attention. Acridine derivatives have been studied in detail and have been found to possess multitarget properties, which inhibit topoisomerase enzymes that regulate topological changes in DNA and interfere with the essential biological function of DNA. This article describes some recent advancements in the field of new 9-substituted acridine heterocyclic agents and describes both the structure and the structure-activity relationship of the most promising molecules. The article will also present the IC50 values of the novel derivatives against various human cancer cell lines. The mini review also investigates the topoisomerase inhibition and antibacterial and antimalarial activity of these polycyclic aromatic derivatives.

Proflavine/acriflavine derivatives with versatile biological activities.

Proflavine derivatives are extremely interesting chemotherapeutic agents, which have shown promising pharmaceutical potential due to their wide range of biological activities. This review summarizes the current state of research into the anticancer, antimicrobial, antimalarial and antileishmanial properties of these attractive compounds. Our attention has focused on new classes of proflavine conjugates, which display significant levels of anticancer activity. Highly promising cytotoxic properties have been identified in proflavine conjugates with imidazolidinones, ureas and thioureas. In particular, proflavine-dialkyldithioureas displayed substantial cytotoxic effect against the human leukemia HL-60 cells with IC50 values from 7.2 to 34.0 µm. As well, palladium complexes with proflavine ligand have important biologic activity. The LC50 values of these complexes were significantly lower than that of cisplatin against the SK-BR-3 cell line.

Fluorinated 3,6,9-trisubstituted acridine derivatives as DNA interacting agents and topoisomerase inhibitors with A549 antiproliferative activity.

A series of new 3,6,9-trisubstituted acridine derivatives with fluorine substituents on phenyl ring were synthesized and their interaction with calf thymus DNA was investigated. Analysis using UV-Vis absorbance spectra provided valuable information about the formation of the acridine-DNA complex. In addition, compounds 8b and 8d were found to display an increased binding affinity (K = 2.32 and 2.28 × 106 M-1, respectively). Topo I/II inhibition mode assays were also performed, and the results verify that the novel compounds display topoisomerase I and II inhibitory activity; compounds 8a, 8b and 8c completely inhibited topoisomerase I activity at a concentration of 60 × 10-6 M, but only compound 8d showed partial ability to inhibit topoisomerase II at concentrations of 30 and 50 × 10-6 M. The ability of the derivatives to impair cell proliferation was tested through an analysis of cell cycle distribution, quantification of cell number, viability studies, metabolic activity measurement and clonogenic assay. The content and localization of the derivatives in cells were analyzed using flow cytometry and fluorescence microscopy. The compounds 8b and 8d altered the physiochemical properties and improved antiproliferative activity in A549 human lung carcinoma cells (compound 8d displayed the highest level of activity, 4.25 × 10-6 M, after 48 h).

In vitro investigating of anticancer activity of new 7-MEOTA-tacrine heterodimers.

A combination of biochemical, biophysical and biological techniques was used to study calf thymus DNA interaction with newly synthesized 7-MEOTA-tacrine thiourea 12-17 and urea heterodimers 18-22, and to measure interference with type I and II topoisomerases. Their biological profile was also inspected in vitro on the HL-60 cell line using different flow cytometric techniques (cell cycle distribution, detection of mitochondrial membrane potential dissipation, and analysis of metabolic activity/viability). The compounds exhibited a profound inhibitory effect on topoisomerase activity (e.g. compound 22 inhibited type I topoisomerase at 1 µM concentration). The treatment of HL-60 cells with the studied compounds showed inhibition of cell growth especially with hybrids containing thiourea (14-17) and urea moieties (21 and 22). Moreover, treatment of human dermal fibroblasts with the studied compounds did not indicate significant cytotoxicity. The observed results suggest beneficial selectivity of the heterodimers as potential drugs to target cancer cells.

Proliferation inhibition of novel diphenylamine derivatives.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most widely used drugs in the world but some NSAIDs such as diclofenac and tolfenamic acid display levels of cytotoxicity, an effect which has been attributed to the presence of diphenylamine contained in their structures. A novel series of diphenylamine derivatives were synthetised and evaluated for their cytotoxic activities and proliferation inhibition. The most active compounds in the cytotoxicity tests were derivative 6g with an IC50 value of 2.5 ±â€¯1.1 × 10-6 M and derivative 6f with an IC50 value of 6.0 ±â€¯3.0 × 10-6 M (L1210 cell line) after 48 h incubation. The results demonstrate that leukemic L1210 cells were much more sensitive to compounds 6f and 6g than the HEK293T cells (IC50 = 35 × 10-6 M for 6f and IC50 > 50 × 10-6 M for 6g) and NIH-3T3 (IC50 > 50 × 10-6 M for both derivatives). The IC50 values show that these substances may selectively kill leukemic cells over non-cancer cells. Cell cycle analysis revealed that a primary trend of the diphenylamine derivatives was to arrest the cells in the G1-phase of the cell cycle within the first 24 h. UV-visible, fluorescence spectroscopy and circular dichroism were used in order to study the binding mode of the novel compounds with DNA. The binding constants determined by UV-visible spectroscopy were found to be in the range of 2.1-8.7 × 104 M-1. We suggest that the observed trend for binding constant K is likely to be a result of different binding thermodynamics accompanying the formation of the complexes.

Multifunctional properties of novel tacrine congeners: cholinesterase inhibition and cytotoxic activity.

This review describes the synthesis of a wide range of novel tetrahydroacridine derivatives (tiocyanates, selenocyanates, ureas, selenoureas, thioureas, isothioureas, disulfides, diselenides and several tacrine homo- and hetro-hybrids). These tacrine congeners exhibit significant anticholinesterase and cytotoxic properties and may therefore be of considerable potential for the development of new drugs for the treatment of Alzheimer's disease.

Sulfur Containing Acridine Derivatives in Preclinical Studies with Cancer Cell Lines.

BACKGROUND: The possible use of acridines as anticancer agents was first considered in the 1920´s. Since then, a large number of acridine drugs have been tested as antitumour agents, including compounds containing sulphur on the acridine chromophore. In this review, we will discuss recent studies which have investigated the anticancer activity of this class of acridine derivatives. METHODS: We present the results both of our own decade-long research and also of existing research literature into the anticancer activity of acridine derivatives containing sulphur. The evidence of specific tumor-cell killing properties displayed by these compounds suggest the potential of using such molecules as anticancer therapeutics. RESULTS: During the last decade, a number of acridine analogs have been developed by modifying the position and the nature of the substituent on the acridine core. In this paper, we published results on the anticancer activity of acridine derivatives containing sulfur (acridine thioureas, acridine thiazolidine/thiazoidinone, and acridine thiosemicarbazones/ thiosemicarbazides). In cancer chemotherapy, the mechanism of the drugs is complex, although the study of the anticancer activity of acridines has yielded exciting results. CONCLUSION: In this review we have summarized recent literature on the anticancer activity of acridine derivatives containing sulfur. A considerable amount of published data suggests that these compounds exhibit promising anticancer activity against selected cancer cell lines. The obtained results can be helpful in the development of new pharmaceutical agents.

A review on acridinylthioureas and its derivatives: biological and cytotoxic activity.

Acridines possess two characteristics that have led many researchers to consider the agents interesting targets for future development as potential farmacophores: the planar acridine skeleton, which is able to intercalate into DNA, and the intense fluorescence of the agents. This review offers a study of the multifunctional character of acridines and the synthesis of novel acridine derivatives, with particular focus being placed on isothiocyanates and their congeners, e.g. thioureas, isothioureas, quaternary ammonium salts and platinum/gold conjugates. The review provides an overview of the structure, spectral properties, DNA binding and biological activity of acridinylthiourea congeners. These acridinylthiourea derivatives display significant cytotoxic activities against different types of cancer cell lines at micromolar concentrations. Copyright © 2017 John Wiley & Sons, Ltd.

3-[(E)-(acridin-9'-ylmethylidene)amino]-1-substituted thioureas and their biological activity.

This paper describes the synthesis of a novel series of acridine thiosemicarbazones through a two-step reaction between various isothiocyanates and hydrazine followed by treatment with acridin-9-carbaldehyde. The properties of this series of seven new derivatives are studied using NMR and biochemical techniques, and the DNA-binding properties of the compounds are determined using spectrophotometric studies (UV-vis absorption, fluorescence, and circular/linear dichroism) and viscometry. The binding constants K are estimated as being in the range of 2.2 to 7.8×104M-1 and the percentage of hypochromism was found to be 22.11-49.75% (from UV-vis spectral titration). Electrophoretic experiments prove that the novel compounds demonstrate moderate inhibitory effects against Topo I activity at a concentration of 60×10-6M.

New spiro tria(thia)zolidine-acridines as topoisomerase inhibitors, DNA binders and cytostatic compounds.

Three new diphenylsubstituted spirotriazolidine- and thiazolidinone-acridines were prepared and their interaction with calf thymus DNA investigated with UV-vis, fluorescence, circular dichroism spectroscopy and viscometry. The binding constants K were estimated to range from 0.34 to 0.93 × 10(4) M(-1). UV-vis, fluorescence and circular dichroism measurements indicated that the compounds act as effective DNA-interacting agents. Electrophoretic separation proved that ligands inhibited topoisomerase I and II. The biological activity of compounds 3, 5 &6 at several different concentrations (10, 20 and 50 µM) was evaluated both 48 h and 72 h following their addition to HL-60 cancer cells. The results were analysed using various different techniques (MMP detection, changes in metabolic activity/viability and analysis of cell cycle distribution). Acridine was also used as the positive control in these assays. The results from MMP analysis demonstrate the strong effect of 3-diphenylamino-2-(acridin-9-yl)imino-1,3-thiazolidin-4-one (5) on mitochondrial physiology. Cell viability analysis showed that acridine derivatives 3 and 6 were less effective than derivative 5 and the acridine control.

Inhibition of DNA topoisomerases I and II and growth inhibition of HL-60 cells by novel acridine-based compounds.

HL-60 cancer cells were treated with a series of novel acridine derivatives (derivatives 1-4) in order to test the compounds' ability to inhibit both cancer cell growth and topoisomerase I and II activity. Binding studies of derivatives 1-4 with calf thymus DNA were also performed using a number of techniques (UV-Vis and fluorescence spectroscopy, thermal denaturation, linear dichroism and viscometry) to determine the nature of the interaction between the compounds and ctDNA. The binding constants for the complexes of the studied acridine derivatives with DNA were calculated from UV-Vis spectroscopic titrations (K=3.1×10(4)-2.0×10(3)M(-1)). Some of the compounds showed a strong inhibitory effect against Topo II at the relatively low concentration of 5µM. Topo I/II inhibition mode assays were also performed and verified that the novel compounds are topoisomerase suppressors rather than poisons. The biological activities of derivatives were studied using MTT assay and flow cytometric methods (detection of mitochondrial membrane potential, measurement of cell viability) after 24 and 48h incubation. The ability of derivatives to impair cell proliferation was tested by an analysis of cell cycle distribution.

Tacrine derivatives as dual topoisomerase I and II catalytic inhibitors.

This study examines the binding properties of a series of newly synthetized tacrine derivatives 1-4 and their anticancer effects. Spectroscopic techniques (UV-Vis, fluorescence spectroscopy, thermal denaturation, and linear spectropolarimetry) and viscometry were used to study DNA binding properties and to determine the types of DNA interaction with the studied derivatives. The binding constants for the complexes with DNA were obtained using UV-Vis spectroscopic titrations (K = 1.6 × 10(4)-4.0 × 10(5) M(-1)) and electrophoretic methods were used to determine the effect of the derivatives on topoisomerase I and II activity. Monotacrine derivative 1 showed evidence of topoisomerase Irelaxation activity at a concentration of 30 × 10(-6) M, while bistacrine derivatives 2-4 produced a complete inhibition of topoisomerase Iat a concentration of 5 × 10(-6) M. The biological activities of the derivatives were studied using MTT-assay and flow cytometric methods (detection of mitochondrial membrane potential and measurement of cell viability) following incubation of 24 and 48 h with human leukemic cancer cell line HL60. The ability of the derivatives to impair cell proliferation was also tested through the analysis of cell cycle distribution.