Acridine derivatives: a patent review (2009 – 2010)

Searching for Conjugates as New Structures for Antifungal Therapies

The progressive increase in fungal infections and the decrease in the effectiveness of current therapy explain research on new drugs. The synthesis of compounds with proven antifungal activity, favorable physicochemical and pharmacokinetic properties affecting their pharmaceutical availability and bioavailability, and limiting or eliminating side effects has become the goal of many studies. The publication describes the directions of searching for new compounds with antifungal activity, focusing on conjugates. The described modifications include, among others, azoles or amphotericin B in combination with fatty acids, polysaccharides, proteins, and synthetic polymers. The benefits of these combinations in terms of activity, mechanism of action, and bioavailability were indicated. The possibilities of creating or using nanoparticles, "umbrella" conjugates, siderophores (iron-chelating compounds), and monoclonal antibodies were also presented. Taking into account the role of vaccinations in prevention, the scope of research related to developing a vaccine protecting against fungal infections was also indicated.

Crystal structure of 9-aminoacridinium chloride N,N-dimethylformamide monosolvate

9-Aminoacridinium chloride N,N-dimethylformamide monosolvate, C13H11N2 +Cl−·C3H7NO, crystallizes in the monoclinic space group P21/c. The salt was crystallized from N,N-dimethylformamide. The asymmetric unit consists of two C13H11N2 +Cl− formula units. The 9-aminoacridinium (9-AA) molecules are protonated with the proton on the N atom of the central ring. This N atom is connected to an N,N-dimethylformamide molecule by a hydrogen bond. The H atoms of the amino groups create short contacts with two chloride ions. The 9-AA cations in adjacent layers are oriented in an antiparallel manner. The molecules are linked via a network of multidirectional π–π interactions between the 9-AA rings, and the whole lattice is additionally stabilized by electrostatic interactions between ions.

A new 1-nitro-9-aminoacridine derivative targeting yeast topoisomerase II able to overcome fluconazole-resistance

Fungal resistance remains a significant threat and a leading cause of death worldwide. Thus, overcoming microbial infections have again become a serious clinical problem. Although acridine derivatives are widely analyzed as anticancer agents, only a few reports have demonstrated their antifungal activity. In an effort to develop biologically active antifungals, twelve novel C-857 (9-(2'-hydroxyethylamino)-1-nitroacridine) and C-1748 (9-(2'-hydroxyethylamino)-4-methyl-1-nitroacridine) derivatives were synthesized. The evaluation of biological properties suggests that starting compounds: C-1748, C-857 and IE3 (2-[(4-methyl-1-nitroacridin-9-yl)amino]ethyl lysinate), IE4 (2-[(1-nitroacridin-9-yl)amino]ethyl lysinate) antifungal mode of action differ from that determined for IE5 (N'-{3-[(4-methyl-1-nitroacridin-9-yl)amino]propyl}lysinamide), IE6 (N'-{3-[(1-nitroacridin-9-yl)amino]propyl}lysinamide) and IE10 (3,3'-Bis-(1-nitroacridin-9-ylamino)-aminoethylaminoethylaminoethylamine). Although MIC values determined for the latter were higher, in contrast to C-857 and C-1748, newly synthesized IE5, IE6 and IE10 reduced C. albicans hyphal growth in different inducing media. Those compounds also exhibited antibiofilm activity, whereas IE10 was the most effective. Moreover, only IE6 exhibited antifungal activity against fluconazole resistant C. albicans strains with MICs values in the range of 16-64 μg mL^-1. Our results also indicate that, in contrast to other analyzed derivatives, novel synthetized compounds IE6 and IE10 with antifungal activity target yeast topoisomerase II activity.

Synthesis, Biological Evaluation and Stability Studies of Some Novel Aza-Acridine Aminoderivatives

Several new amino-substituted aza-acridine derivatives bearing a basic side chain have been designed and synthesized. The antiproliferative activity of the target compounds has been evaluated against three cancer cell lines-namely HCT-116 (colorectal), the uterine sarcoma MES-SA, and its doxorubicin-resistant variant MES-SA/Dx5. A limited number of the new acridines showed marginal cytotoxicity against the tested cell lines; nevertheless, these analogues possessed a similar substitution pattern. The moderate biological activity of these derivatives was attributed to their instability in aqueous media, which has been studied by mass spectrometry and computational chemistry experiments at the density functional level of theory (DFT).

Three Multi-Components Reaction: Synthesis and X-Ray Single-Crystal of Hydroacridinone-Based Hydrazino-S-Triazine Derivative as a New Class of Urease Inhibitor

The one-pot fashion of three multi-component reaction provides the desired hydroacridinone-based hydrazino-s-triazine scaffold 4. Compound 4 was crystallized in an orthorhombic crystal system and Pbca space group with a = 11.6271(2) Å, b = 18.2018(4) Å, c = 32.4721(6) Å, and α = β = γ = 90° with one formula unit per asymmetric unit and eight molecules per unit cell. Additionally, structural features, Hirshfeld surfaces, and DFT studies were also investigated. Its packing in the crystal is controlled by H…H (63.4%), O…H (12.7%), Cl…H (7.2%), N…H (4.7%), and C…H (10.2%) contacts, where the O…H and Cl…H contacts were found the strongest. In vitro urease inhibition evaluation showed that the hydroacridinone-based hydrazino-s-triazine is more active (IC50 = 17.9 ± 0.47 µM) than the standard acetohydroxamic acid (IC50 = 20.3 ± 0.43 µM).

Cascade intramolecular imidoylation and C–H activation/annulation of benzimidoyl chlorides with alkynes: one-pot synthesis of 7H-dibenzo[de,h]quinoline analogues

Described herein is a cascade Lewis acid-promoted intramolecular Friedel–Crafts-type imidoylation and Rh(iii)-catalyzed C–H activation/annulation of benzimidoyl chlorides and alkynes, providing a divergent synthetic shortcut to 7H-dibenzo[de,h]quinoline analogues.

Combing metabolomics with bioanalysis methods to study the antitumor mechanism of the new acridone derivative 8q on CCRF-CEM cells: 8q induced mitochondrial-mediated apoptosis and targeted the PI3K/AKT/FOXO1 pathway

A novel acridone derivative, N-(2-(dimethylamino)ethyl)-1-((3-methoxybenzyl)amino)-5- nitro-9-oxo-9,10-dihydro-acridine-4-carboxamide (8q), which was synthesized in our lab, showed potent anti-leukaemia activity against CCRF-CEM cells. Moreover, in silico predictions showed that 8q conformed to the rule of five and displayed low toxicity. However, the mechanism of anti-leukaemia action remains unclear. The aim of this research was to reveal the probable anti-leukaemia mechanism of 8q on CCRF-CEM cells. Flow cytometry assay demonstrated that 8q induced apoptosis. The expression of caspase family proteins results showed that 8q could only promote cleaved caspase-3, 7 and 9 expressions without affecting cleaved caspase-8 protein, hinting that 8q induced mitochondrial-mediated apoptosis. Further, we detected 3 indicators of mitochondrial lesions, including increased of Cyt-C release, with a decrease in MMP and ATP levels. Next, metabolomics were introduced to assist in the research of the anti-leukaemia mechanism of 8q. The metabolomics results showed that 100 nM 8q could increase the level of GSH, and decrease its oxidation products. These indicated 8q could influence the ROS, which derived by mitochondria. Then we examined the effect of 8q on intracellular ROS levels. What is particularly interesting is that 8q inhibited cell ROS stress at low concentration and stimulated ROS stress at high concentration. The pro-apoptosis mechanisms of 8q were then explored. 8q significantly decreased anti-apoptotic proteins Bcl-2 and Bcl-xL expression, whereas it up-regulated the pro-apoptotic proteins Bax, Bak, Bad, Bik and Puma expression. In addition, 8q dramatically inhibited the expression of FASN, which is related to fatty acid metabolism. Furthermore, PI3K, AKT and FOXO1 were inactivated, and the expression of total AKT was also inhibited by 8q treatment, which promoted intrinsic apoptosis. In conclusion, these findings demonstrate that 8q can induce mitochondrial lesions and promote mitochondrial-mediated pathway apoptosis by regulating the expression of Bcl-2 family proteins and inhibiting the activity of the PI3K/AKT/FOXO1 signaling pathway.

Synthesis and biological study of acridine-based imidazolium salts

A new series of acridine based imidazolium salts was synthesized and evaluated for in vitro cytotoxicity against human cancer cell lines by an MTT assay. The synthesis applied a coupling of imidazoles with 9-chloroacridines, which originated from an Ullmann condensation of a 2-chloro-benzoic acid with an aniline. The target compounds were obtained in high yields. The DPPH assay indicated considerable antioxidant activity for target compounds with simple and short alkyl chains on the imidazole, while increasing chain length and the introduction of an additional π-electron system in most cases reduced the activity. All compounds exhibited low biotoxicity against non-cancerous cell lines, whereas a few compounds showed promising anticancer activity. Unlike for the reference drugs Tamoxifen and Paclitaxel, the anticancer activity of acridine imidazolium ions is specific for only selected cancer types. Reasonable fluorescent behaviour of the products provide potential for visualization of the distribution of active drugs in tissue.

A series of acridine-based imidazolium salts was synthesized and studied on cytotoxicity against human cancer cell lines.

l-Proline-Catalysed the Synthesis of Aromatic Aldehydes and Ketones and their Acridione Derivatives at Room Temperature

A series of xanthene derivatives were prepared from cyclohexane-1,3-dione and aromatic aldehydes through Knoevenagel–Michael and cyclisation reactions in methanol:ethanol mixture (1:1), catalysed by a very small amount of l-proline at room temperature. Isomeric tetraketones were synthesised from dimedone and aromatic aldehydes under the same condition. Condensation of them with amines gave acridione derivatives. The crystal structure of an acridione was obtained and determined by X-ray single-crystal diffraction.

Synthesis of 10-Substituted 3,6-Diphenyl-9-Aryl-3,4,6,7,9,10-Hexahydroacridine-1,8(2H,5H)-Dione Derivatives

A series of novel 10-substituted 3,6-diphenyl-9-aryl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione derivatives synthesised by condensation of different amines with xanthenes, was prepared from 5-phenylcyclohexane-1,3-dione and aromatic aldehydes by a Knoevenagel and Michael reaction and cyclisation catalysed by a trace of l-proline at room temperature. In addition, the molecular structure of a xanthene was determined by single-crystal X-ray diffraction analysis.

A POCl3-mediated synthesis of substituted fused azoacridones derivatives

We provide an efficient approach to synthesize fused azoacridone derivatives, which showed broad substrate scope and good yields.

Novel synthetic acridine derivatives as potent DNA-binding and apoptosis-inducing antitumor agents

Acridine derivatives have been explored as DNA-binding anticancer agents. Some derivatives show undesired pharmacokinetic properties and new derivatives need to be explored. In this work, a series of novel acridine analogues were synthesized by modifying previously unexplored linkers between the acridine and benzene groups and their antiproliferative activity and the DNA-binding ability were evaluated. Among these derivatives, compound 5c demonstrated DNA-binding capability and topoisomerase I inhibitory activity. In K562 cell lines, 5c induced apoptosis through mitochondria-dependent intrinsic pathways. These data suggested that compound 5c and other acridine derivatives with modified linkers between the acridine and benzene groups might be potent DNA-binding agents.