9-aminoacridine Research Articles

Design, Synthesis, Evaluation and Toxicity Studies of Novel Acridine Derivatives in Zebra Fish Larvae

Background: Alzheimer’s disease (AD) is a complex neurodegenerative condition for which a single protein-targeting medication is not enough to provide a cure. All the medications now available for AD are palliative. FDA has approved five medications for the treatment of AD, i.e., tacrine, donepezil, galantamine, rivastigmine, and memantine. Due to hepatotoxicity, tacrine is no longer utilized in clinical practice. Due to the lack of therapeutic efficiency of single-target medications and the multifaceted etiology of AD, multitarget-directed ligands have been developed. Objectives: The present research focused on incorporating a flavone nucleus into the amino group of 9-amino acridine nucleus to make it an acetylcholinesterase (AChE) and butyryl cholinesterase inhibitor (BuChE) with less toxicity Methods: We designed and synthesized ten flavone-substituted acridine derivatives and evaluated them for in vitro AChE and BuChE inhibitory activity. Molecular modeling studies were conducted using AutoDock Vina with hAChE (PDB ID: 4EY7) and hBuChE (PDB ID: 4TPK). The toxicity profile of the most active novel compound tested on zebrafish larvae for determining the liver and cardiac toxicity and LD50 value of the compound were determined. Results: In vitro AChE and BuChE inhibitory study by Ellman assay showed acceptable results. The compound AF2 showed the highest activity with an IC50 value of 0.99 ± 0.1 µM for AChE and 1.78 ± 0.19 for BuChE. The in vivo acute toxicity studies conducted on zebra fish larvae did not show cardiac and hepatotoxicity, and the LD50 value was found to be 1000 µL Conclusion: The results highlighted the AChE and BuChE inhibitory effects of the novel acridine-flavone hybrids, and they can be promising multitarget-directed ligands for AD.

A systematic computational study of acridine derivatives through conceptual density functional theory.

A detailed computational analysis of acridine derivatives viz. acridone, 9-amino acridine hydrochloride hydrate, proflavin, acridine orange and acridine yellow is done in terms of conceptual density functional theory (CDFT). CDFT-based global descriptors-ionization potential, electron affinity, HOMO-LUMO gap, hardness, softness, electronegativity and electrophilicity index of acridine derivatives for ground state as well as excited state are estimated with the help of different hybrid functionals B3LYP/6-31G (d, p), B3LYP/6-311G (d, p), B3LYP/DGDZVP and B3LYP/LANL2DZ. Acridine derivatives show higher values of ionization potential and electron affinity in excited state as compared to ground state, indicating that these compounds are willing to accept electrons in excited state rather than donating electron. Acridone shows the maximum HOMO-LUMO energy gap in ground and excited state which implies that one-way electron transfer is most feasible with this compound. Our computed results emphasize the pronounced electron acceptor behaviour of the acridine derivatives in the excited state which has already been experimentally verified. It is observed that the trend in the computed values of the descriptors is not much improved on refinement of the basis set.

Revisiting magnetic field effects in homogeneous medium and bio-mimicking environments with emphasis on acridine derivatives

A weak external magnetic field, very close to the hyperfine interactions of the system, can acts as a tool to monitor spin dynamics and assess distance between the components of the spin-correlated transient radical pair or radical ion pair (RIP). The present review focuses on the magnetic field effect (MFE) on the photo-induced electron-transfer (PET) reactions among acridine derivatives and classical as well as biological electron acceptor or donor moieties, which produce spin-correlated RIPs, in homogeneous solvents, heterogeneous micellar media and in biological nanocavities of proteins. Although a confined medium is preferred to observe prominent MFE, yet unanticipated MFE on PET between acridine derivatives [Acridone (AD) and Acridine Yellow (AY)] and classical electron donors is obtained even in homogeneous medium when it consists of impurities like water molecules. In a comparative study of interaction of another acridine derivative, Proflavin (PF+) with two electron donors which are amines of aromatic nature, MFE on PET reveal that the bulk and the structure of the electron donor govern the mechanism as well as the spin dynamics of PET. While studying interaction of PF+ with a different amine which is aliphatic in nature, MFE on PET implies that it is the nature of the solvent matrix which determines the spin dynamics of PET. The cause of discrepancy in the experimental and calculated values of B1/2 for 9-amino acridine – methyl viologen system has been delineated. Apart from micellar medium, prominent MFE on PET is also observed while studying the interaction of PF+, AY and AD with tryptophan residues present in the nanocavities of serum albumins since the inter-radical distance within primary geminate RIP is enough to make exchange interaction negligible.

Synthesis, characterization, and hypoglycemic efficacy of nitro and amino acridines and 4-phenylquinoline on starch hydrolyzing compounds: an in silico and in vitro study

α-Amylase and α-Glucosidase are important therapeutic targets for type II diabetes. The present focus of our study is to elucidate the hypoglycemic activity of novel compounds through in vitro and in silico studies. Here, we synthesized the nitro acridines (3a–3c), amino acridines (4a–4c), and nitro phenylquinoline (3d) and amino phenylquinoline (4d) using a multi-step reaction protocol in good yields. All the above derivatives were screened for molecular docking, α-Amylase and α-Glucosidase inhibitory activities utilizing acarbose as standard drug. In silico studies were performed to explore the binding ability of compounds with the active site of α-Amylase and α-Glucosidase enzymes. The in vitro antihyperglycemic report of 3c exhibits the maximum inhibitory activity with IC50 values of 200.61 ± 9.71 μmol/mL and 197.76 ± 8.22 μmol/mL against α-Amylase and α-Glucosidase, respectively. Similarly, the compound 3a exhibits IC50 values of 243.78 ± 13.25 μmol/mL and 296.57 ± 10.66 μmol/mL, and 4c exhibits IC50 values of 304.28 ± 3.51 μmol/mL and 278.86 ± 3.24 μmol/mL with a significant p < 0.05 in both enzyme inhibitions. In addition, the presence of diverse functional moieties in synthesized compounds may provide a strong inhibitory action against the abovementioned enzymes compared with standard acarbose inhibition (IC50, 58.74 ± 3.68 μmol/mL and 49.39 ± 4.94 μmol/mL). Also, the docking studies provided an excellent support for our in vitro studies. The outcome of these studies recommends that the tested compounds might be treated as potential inhibitors for the starch hydrolyzing enzymes in type II diabetes.

Novel Aminoacridine Sensors Based on Molecularly Imprinted Hybrid Polymeric Membranes for Static and Hydrodynamic Drug Quality Control Monitoring

Novel biomimetic potentiometric ion-selective electrodes (ISEs) were fabricated and designed for the assessment of aminoacridine (ACR) based on newly synthesized imprinted polymer (MIP) membranes. Thermal polymerization of methacrylic acid (MAA) or acrylamide (AM) as function monomer, aminoacridine as a template and ethylene glycol dimethacrylate (EGDMA) as across-linker, were utilizedto give the molecular recognition part. The membranes of sensors I andII consist of MIP based MAA and AM, respectively, dispersed in a poly(vinyl chloride) membrane plasticized with dioctyl phthalate (DOP) in the ratio of 3.0 wt%, 32.2 wt% and 64.8 wt%, respectively. Sensors III and IV were similarly prepared with added 1.0 wt% tetraphenyl borate (TPB−) as an anionic discriminator. Sensors I and II exhibited near-Nernstian potential response to ACR+ with slopes of 51.2 ± 1.3 and 50.5 ± 1.4 mV/decade in a 0.01 M phosphate buffer of pH 6.0. The linear response coversthe concentration range of 5.2 × 10−6 to 1.0 × 10−3 M with a detection limit of 0.05 and 0.17 μg/mL for sensors I and II, respectively. The performance characteristics of these sensors were evaluated under static and hydrodynamic mode of operations. They were used for quality control assessment of aminoacridine in some pharmaceutical preparations and biological samples.

&amp;lt;i&amp;gt;In-silico&amp;lt;/i&amp;gt; Drug Design, ADMET Screening, MM-GBSA Binding Free Energy of Some Chalcone Substituted 9-Anilinoacridines as HER2 Inhibitors for Breast Cancer

Due to their DNA-intercalating agents 9-aniliinoacridines play an important role as antitumor agents. A Series of some Chalcone substituted 9-aniliinoacridines 1a-x were designed for their anti-breast cancer activity. Molecular docking studies were performed by Glide module of Schrodinger suite-2016, targeted against Human epidermal growth factor receptor HER2 (PDB id-3PP0). <i>In-silico</i> ADMET screening by qikprop module and binding free energy by Prime-MMGBSA module also performed. Based on the binding affinity of the designed molecules with HER2 on the basis of GLIDE score and interaction patterns. Most of the compounds 1a-x have significant Glide scores when compared with standard anticancer drugs ledacrine and tamoxifen. Most of the Chalcone substituted 9-anilinoacridine derivatives 1a-x have good binding affinity with Glide score in the range of -5. 32 to -9.37 compared with the standard ledacrine (-5.23) and tamoxifen (-3.78). The results reveals that, Chalcone substituted 9-amino acridines as HER2 inhibitor and the compounds, 1g, f, b, h, t, u with good Glide score may produce significant anti-breast cancer activity for further refinement.

Photoinduced electronic interactions between acridine derivatives and small gold nanoparticles: A spectroscopic insight

The central tricyclic moiety of acridine derivatives has fascinating redox properties. We take advantage of the electronic properties of two such acridine derivatives, 9-amino acridine (9AA-HCl) and acridine yellow, recognized so far as potential antimicrobial agents, since these drugs can act both as potential electron donor and acceptor, depending upon the reduction potential of its adjacent chemical entity. Precise timescale of formation of contact ion pair (CIP) and solvent separated ion pair in solution involving donors and acceptors has been much encountered and debated in literature till date. In our present communication, we like to decipher the mechanism and timescale of individual steps of photoinduced electron transfer (PET) between these drugs and gold nanoparticles (AuNPs) with dimension of 3-5 nm, which is important and presently our subject of interest since AuNPs could be used for shuttling of electrons between different donor and acceptor moieties. Steady-state and time-resolved absorption and fluorescence studies evidently reveal the signature of PET both in singlet and triplet states. Using ultrafast time-resolved fluorescence techniques we have tried to quantify precisely the time required for formation of CIP which is within fs-ps time regime. Moreover, 9AA-HCl, being a planar molecule, dimerises at excited state in presence of high concentration of AuNPs, due to its immobilisation over their surface. The occurrence of excited state proton transfer in triplet state for 9AA-HCl-AuNPs conjugate is depicted by laser flash photolysis experiments. The presence of all such charge transfer channels, provokes us to delineate the intricacies of the mechanisms involved which would help further to evaluate the possibility of making devices for energy storage using these drugs.

Synthesis of novel 5-amino-1,3,4-thiadiazole-2-sulfonamide containing acridine sulfonamide/carboxamide compounds and investigation of their inhibition effects on human carbonic anhydrase I, II, IV and VII

Herein, we report that acridine intermediates 5 were obtained from the reduction of nitro acridine derivatives 4, which were synthesized via condensation of dimedone, p-nitrobenzaldehyde with 4-amino-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)benzamide, respectively. Then acridine sulfonamide/carboxamide (7a–i) compounds were synthesized by reaction of amino acridine 5 with sulfonyl chlorides and carbamoyl chlorides. The new compounds were characterized by melting points, FT-IR, 1H NMR, 13C NMR and HRMS analyzes. The evaluation of in vitro test of the synthesized compounds against hCA I, II, IV and VII showed that some of them are potent inhibitors. Among them, compound 7e showed the most potent activity against hCA II with a KI of 7.9 nM.

Synthesis of novel acridine-sulfonamide hybrid compounds as acetylcholinesterase inhibitor for the treatment of alzheimer’s disease

In this study we report that amino acridine intermediates 7 and 8 were obtained from the reduction of nitro acridine derivatives 5 and 6 that were synthesized via the condensation of dimedone, p-nitrobenzaldehyde with various amine derivatives, respectively. Then acridine sulfonamide hybrid compounds (9–18) were synthesized by the reaction of amino acridine 7, 8 with sulfonyl chlorides. The new hybrid compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, and HRMS analyzes. The evaluation of in vitro anticholinesterase action of the synthesized compounds against AChE showed that some of them are potent inhibitors. Among them, compound 17 showed the most potent activity against AChE with an IC50 of 0.14 µM.

Synthesis of acridine cyclic imide hybrid molecules and their evaluation for anticancer activity

9-Amino acridine derivatives (1a–e) on condensation with dihydrofuran-2,5-dione, hexahydroisobenzofuran-1,3-dione and isochroman-1,3-dione under microwave irradiation gave corresponding condensation products 2a–e, 3a–e and 4a–e, respectively, in good yields. All these compounds were screened in vitro for anticancer activity against five human cancer cell lines, i.e., breast (T47D), lung (NCl H-522), colon (HCT-15), ovary (PA-1) and liver (Hep G2). Compounds 1-(3-methoxyacridine-9-yl) pyrrolidine-2,5-dione (2d) (ovary PA-1), 2-(2-methylacridine-9-yl)hexahydro-1H-isoindole-1,3(2H)-dione (3b) (lung NCl H-522), 2-(4-methylacridine-9-yl)hexahydro-1H-isoindole-1,3(2H)-dione (3c) (ovary PA-1), 2-(4-methoxyacridine-9-yl)hexahydro-1H-isoindole-1,3(2H)-dione (3e) (ovary PA-1) and 2-(2-methylacridine-9-yl)isoquinoline-1,3(2H,4H)-dione (4b) (ovary PA-1) exhibited IC50 values 7.1, 8.0, 5.4, 10.0 and 6.56 µM, respectively, and hence possess good anticancer activity.

Synthesis and anticancer activity evaluation of some acridine derivatives

9-Amino acridine derivatives (1a–1h) on condensation with 9, 10-dihydroanthracene-9, 10-α, β-succinic anhydride (2) at room temperature gave condensation products (3a–3h). Microwave-assisted condensation of 9-amino acridine derivatives (1a–1d) with phthalic anhydride, cis 1,2,3,6-tetrahydrophthalimide, and 2,5-pyrroledione gave corresponding condensation products 4a–4d, 5a–5d & 6a–6d, respectively, in good yields. All these compounds were screened for in vitro anticancer activity against five human cancer cell lines i.e., breast (T47D), lung (NCl H-522), colon (HCT-15), ovary (PA-1), and liver (Hep G2). Compounds 3a (breast T47D), 3 g (lung NCl H-522), 4a (liver Hep G2), and 6b (colon HCT-15) exhibited IC50 values 5.4, 4.2, 4.5, and 2.4 µM, respectively, and hence possess good anticancer activity.

Elucidation of Selectivity for Uranyl Ions with an ICT Organosilane-Modified Fluorescent Receptor

A fluorescent receptor, isocyanatopropyl trimethoxysilane grafted 9-amino acridine (AcI), was synthesized and characterized by elemental analysis, FTIR and NMR spectroscopy. Photophysical properties and pH-dependent fluorescence behavior of AcI were investigated and its complex stoichiometry with uranyl ion was elucidated. Change in fluorescence emission of AcI with pH of the solution was observed and pKa value was determined by using integrated emission intensity versus pH. It was found that AcI exhibited fluorescence enhancement, which can be attributed to an internal charge transfer (ICT) mechanism, upon titration with uranyl ions in mixture of ethanol-buffer solution while the fluorescence emission of AcI was not affected by addition of other divalent transition metal ions except mercury (II) ions. On the other hand, the both fluorescence and UV-vis titration measurements revealed unique selectivity for uranyl ions over the interfering mercury (II) ions. The spectrofluorometric titration clarified that uranyl interacted with AcI to form AcI 2(UO2(2 +))3 (2:3) complex structure with an apparent association constant of K = 7.41 × 10(6) M(-2/3). The interference effect of some cations on fluorescence enhancement exhibited by complex was also tested.

Correction: Structure and Stability of Human Telomeric G-Quadruplex with Preclinical 9-Amino Acridines

This article was republished on December 3rd, 2013 because of incorrect figure order. Please download this article again to view the figures.

Structure and Stability of Human Telomeric G-Quadruplex with Preclinical 9-Amino Acridines

G-quadruplexes are higher-order DNA structures formed from guanine-rich sequences, and have been identified as attractive anticancer drug targets. Elucidating the three-dimensional structure of G-quadruplex with 9-amino acridines and the specific interactions involved in binding selectivity are the key to understanding their mechanism of action. Fluorescence titration assays, competitive dialysis and NMR studies have been used to study the binding specificity of 9-amino acridines to DNA. Structural models of the complexes with the telomeric DNA G-quadruplex based on NMR measurements were developed and further examined by molecular dynamics simulations and free energy calculations. Selective binding of 9-amino acridines for G-quadruplex sequences were observed. These compounds bind between A and G-tetrads, involving significant π-π interactions and several strong hydrogen bonds. The specific interactions between different moieties of the 9-amino acridines to the DNA were examined and shown to play a significant role in governing the overall stabilities of DNA G-quadruplex complexes. Both 9-amino acridines, with similar binding affinities to the G-quadruplex, were shown to induce different level of structural stabilization through intercalation. This unique property of altering structural stability is likely a contributing factor for affecting telomerase function and, subsequently, the observed differences in the anticancer activities between the two 9-amino acridines.

Energy transfer in 9 amino acridine hydrochloride hydrate to acriflavin and 9 amino acridine hydrochloride hydrate–acriflavin–rhodamine B-doped PVA films

In the present study, excitation energy transfer between the dye pair 9 amino acridine hydrochloride hydrate (9AAHH)–acriflavin and the ternary 9AAHH–acriflavin–rhodamine B (RB) dye system doped in poly-vinyl alcohol (PVA) films was investigated at room temperature. For 9AAHH–acriflavin dye pair, the energy transfer parameters, viz overlap integral ΩDA and critical transfer distance R OA, equalling 1.4×10−13 l cm3 mol−1 and 45.23 Å, respectively, have been obtained. Energy transfer from 9AAHH to RB via acriflavin has also been investigated. These two and three dyes doped transparent polymer films of PVA can be used as efficient materials in luminescent solar collectors.

9-Amino acridine pharmacokinetics, brain distribution, and in vitro/in vivo efficacy against malignant glioma

The delivery of drugs to the brain is a major obstacle in the design and development of useful treatments for malignant glioma. Previous studies by our laboratory have identified a series of 9-amino acridine compounds that block the catalytic cycle of topoisomerase II resulting in apoptosis and cell death in a variety of cancer cell lines. This study reports the in vitro and in vivo activity of two promising lead compounds, [{9-[2-(1H-Indol-3-yl)-ethylamino]-acridin-4-yl}-(4-methyl-piperazin-1-yl)-methanone (1) and [9-(1-Benzyl-piperidin-4-ylamino)-acridin-3-yl]-(4-methyl-piperazin-1-yl)-methanone] (2), using an orthotopic glioblastoma mouse model. In addition, the absorption, distribution, and metabolism properties are characterized by determining metabolic stability, MDCK accumulation, Pgp efflux transport, plasma protein binding, and brain distribution in mouse pharmacokinetic studies. The efficacy results indicate low micromolar ED(50) values against glioma cells and a significant increase in the survival of glioma-bearing mice dosed with (2) (p<0.05). Pharmacokinetic data collected at time intervals following a 60mg/kg oral dose of acridine 1 and 2 showed both compounds penetrate the blood-brain barrier yielding peak concentrations of 0.25μM and 0.6μM, respectively. Peak plasma concentrations were determined to be 2.25μM (1) and 20.38μM (2). The results were further compared with data collected using a 15mg/kg intravenous dose of 2 which yielded a peak concentration in the brain of 1.7 μM at 2.0h relative to a 2.04 μM peak plasma concentration. The bioavailability was calculated to be 83.8%. Taken overall, the results suggest compounds in this series may offer new strategies for the design of chemotherapeutics for treating brain cancers with high oral bioavailability and improved efficacy.

Quinacrine and 9-Amino Acridine Inhibit B-Z and B-HL Form DNA Conformational Transitions

The interaction of quinacrine and 9-amino acridine with right-handed B-form, left-handed Z-form, and left-handed protonated (H(L))-form structures of polydG-me(5)dC was investigated by circular dichroism and absorption spectral analysis. Both the compounds bind strongly to the B-form structure and convert the Z-form and H(L)-form back to the bound right-handed form. Circular dichroic data revealed that the conformation at the binding site is right-handed even though adjacent regions of the polynucleotide may have left-handed conformation. The rate and extent of B-form-to-Z-form transition were decreased in the presence of these compounds. Scatchard analysis revealed that both quinacrine and 9-amino acridine bind strongly to the polynucleotide in the B-form in a noncooperative manner, in sharp contrast to the highly cooperative binding to the Z-form and H(L)-form. Results indicated that the cooperative binding of these drugs with the Z-form and the H(L)-forms was associated with a sequential conversion of the polynucleotide from a left-handed to a bound right-handed conformation. Experimental data enabled the calculation of the number of base pairs of Z-form (7-8 with quinacrine and 9-amino acridine) and H(L)-form (4 and 25, respectively, with quinacrine and 9-amino acridine) that adopt a right-handed conformation for each bound ligand. As these compounds are known to bind preferentially to alternating guanine--cytosine sequences, which are capable of easily undergoing the B-to-Z or B-to-H(L) transition, these effects may be important in understanding their biological activities.

Excited state properties of 9-amino acridine surface adsorbed onto αZr-phosphate particles

In this report the photo-physical properties of 9-amino acridine (9AA) associated with αZr-phosphate particles (αZrP) is examined. In ethanol solution 9AA exhibits absorption maxima at 425 nm, 402 nm and 383 nm as well as emission bands centered at 455 nm and 483 nm (using 423 nm excitation). The corresponding emission decay is monophasic with a lifetime of 16.5 ns. When αZrP is sonicated in the presence of an ethanol solution of 1 mM 9AA the resulting material exhibits a broad absorption band centered at ∼400 nm with shoulders at ∼425 nm and ∼385 nm and emission bands at 462 nm and 485 nm (using 423 nm excitation). Interestingly, the emission decay is biphasic with lifetimes of 1.6 ns and 9.8 ns constituting 57% and 43% of the total emission intensity, respectively. The absence of any shifts in the low angle XRD data suggests that 9AA associates via adsorption onto the exterior surfaces of the αZrP particles. Overall, these results are consistent with different modes of 9AA association to αZrP reflecting different degrees of H-bonding which significantly influences the extent of non-radiative decay from the lowest excited singlet state of 9AA.

9-Amino Acridines Undergo Reversible Amine Exchange Reactions in Water: Implications on Their Mechanism of Action in Vivo

9-Amino substituted acridines undergo a reversible amine exchange reaction in water under near-physiological conditions via an unstable hemiaminal intermediate. This thermodynamically controlled reaction may have implications in understanding the mode of action of 9-aminoacridines in vivo and in the future design of drugs based on this scaffold.

Semi-synthetic and synthetic 1,2,4-trioxaquines and 1,2,4-trioxolaquines: synthesis, preliminary SAR and comparison with acridine endoperoxide conjugates

A novel series of semi-synthetic trioxaquines and synthetic trioxolaquines were prepared, in moderate to good yields. Antimalarial activity was evaluated against both the chloroquine-sensitive 3D7 and resistant K1 strain of Plasmodium falciparum and both series of compounds were shown to be active in the low nanomolar range. For comparison the corresponding 9-amino acridine analogues were also prepared and shown to have low nanomolar activity like their quinoline counterparts.