Synthesis and cytotoxic activity evaluation of novel imidazopyridine carbohydrazide derivatives.

Two series of novel imidazo[1,2-a]pyridine-2-carbohydrazide derivatives have been designed, synthesized, and evaluated for cytotoxic activity. Target compounds were designed in two series: aryl hydrazone derivatives that were devoid of triazole moiety (7a-e) and aryl triazole bearing group (11a-e). In vitro cytotoxicity screening was carried out using MTT assay against three human cancer cells including breast cancer (MCF-7), colon cancer (HT-29), and leukemia (K562) cell lines as well as a non-cancer cell line (Vero). Compound 7d bearing 4-bromophenyl pendant from aryl hydrazone series exhibited the highest cytotoxic potential with IC50 values of 22.6 µM and 13.4 µM against MCF-7 and HT-29 cells, respectively, while it was not toxic towards non-cancer cells up to the concentration of 100 µM. Cell cycle analysis revealed that 7d increased the number of MCF-7 cells in the G0/G1 phase and also induced apoptosis in these cells as revealed by Hoechst 33,258 staining. The molecular mechanism contributing to the anti-proliferative effect of the most potent compound was investigated in silico using Super Pred software and introduced PDGFRA as a plausible target for 7d. Molecular docking and molecular dynamic studies demonstrated Lys627 and Asp836 as key residues interacting with the active compound. Overall, 7d could serve as a suitable candidate for further modifications as a lead anticancer structure.

Novel Benzotriazole-ß-lactam Derivatives as Antimalarial Agents: Design, Synthesis, Biological Evaluation and Molecular Docking Studies.

Many people around the world suffer from malaria, especially in tropical or subtropical regions. While malaria medications have shown success in treating malaria, there is still a problem with resistance to these drugs. Herein, we designed and synthesized some structurally novel benzotriazole-ß-lactams using 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid as a key intermediate. To synthesize the target molecules, the ketene-imine cycloaddition reaction was employed. First, The reaction of 1H-benzo[d][1,2,3]triazole with 2-bromoacetic acid in aqueous sodium hydroxide yielded 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid. Then, the treatment of 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid with tosyl chloride, triethyl amine, and Schiff base provided new ß-lactams in good to moderate yields.The formation of all cycloadducts was confirmed by elemental analysis, FT-IR, NMR and mass spectral data. Moreover, X-ray crystallography was used to determine the relative stereochemistry of 4a compound. The in vitro antimalarial activity test was conducted for each compound against P. falciparum K1. The IC50 values ranged from 5.56 to 25.65 µM. A cytotoxicity profile of the compounds at 200 µM final concentration revealed suitable selectivity of the compounds for malaria treatment. Furthermore, the docking study was carried out for each compound into the P. falciparum dihydrofolate reductase enzyme (PfDHFR) binding site to analyze their possible binding orientation in the active site.

Voltage-Gated Na+ Channels in Alzheimer's Disease: Physiological Roles and Therapeutic Potential.

Alzheimer's disease (AD) is the most common cause of dementia and is classically characterized by two major histopathological abnormalities: extracellular plaques composed of amyloid beta (Aß) and intracellular hyperphosphorylated tau. Due to the progressive nature of the disease, it is of the utmost importance to develop disease-modifying therapeutics that tackle AD pathology in its early stages. Attenuation of hippocampal hyperactivity, one of the earliest neuronal abnormalities observed in AD brains, has emerged as a promising strategy to ameliorate cognitive deficits and abate the spread of neurotoxic species. This aberrant hyperactivity has been attributed in part to the dysfunction of voltage-gated Na+ (Nav) channels, which are central mediators of neuronal excitability. Therefore, targeting Nav channels is a promising strategy for developing disease-modifying therapeutics that can correct aberrant neuronal phenotypes in early-stage AD. This review will explore the role of Nav channels in neuronal function, their connections to AD pathology, and their potential as therapeutic targets.

Design, Synthesis, in Vitro, and in Silico Evaluation of N-Phenylacetamide-Oxindole-Thiosemicarbazide Hybrids as New Potential Tyrosinase Inhibitors.

A novel series of N-phenylacetamide-oxindole-thiosemicarbazide hybrids were synthesized and evaluated for their tyrosinase inhibitory activity. According to tyrosinase inhibition results, all the synthesized compounds showed high tyrosinase inhibitory activity with IC50 values ranging from 0.8 to 3.88 µM in comparison to positive control kojic acid with IC50 value of 36.32 µM. Among tested compounds, analog 7o, containing the 2-methyl-4-nitrophenyl on N-phenylacetamide moiety displayed superior tyrosinase inhibition. This compound was around 45-fold more potent than kojic acid. The kinetic analysis of compound 7o demonstrated that this compound is a competitive inhibitor against tyrosinase. Docking study of this compound demonstrated that compound 7o interacted with critical histidine residues within tyrosinase active site.

The possible effect of microRNA-155 (miR-155) and BACE1 inhibitors in the memory of patients with down syndrome and Alzheimer's disease: Design, synthesis, virtual screening, molecular modeling and biological evaluations.

MiR-155 plays main roles in several physiological and pathological mechanisms, such as Down syndrome (DS), immunity and inflammation and potential anti-AD therapeutic target. The miR-155 is one of the overexpressed miRNAs in DS patients that contribute directly and indirectly to the onset or progression of the DS. Since the miR-155 can simultaneously reduce the translation of several genes at post-transcriptional levels, targeting the miR-155 might set the stage for the treatment of DS. One of the rational strategies in providing therapeutic interventions in this respect is to design and develop novel small molecules inhibiting the miR-155 function or biogenesis or maturation. In the present study, we aim to introduce small molecule compounds with the potential to inhibit the generation of the selectively miR-155 processing by employing computational drug design approaches, as well as in vitro studies. We designed and synthesized a novel series of imidazo[1,2-a]pyridines derivatives as new nonpeptic candidates for the treatment of DS with AD. The designed compounds were investigated for their BACE1 and miR-155 binder inhibitory potential in vitro and in cell. In addition, we present a systematic computational approach that includes 3 D modeling, docking-based virtual screening, and molecular dynamics simulation to identify Small - molecule inhibitors of pre-miR-155 maturation. To confirm the inhibitory potential of compound 8k on miR-155 maturation, qRT- PCR was performed. All our results confirm that compound 8k, in addition to being a good inhibitor of BACE1, can also be a good inhibitor of miR-155.Communicated by Ramaswamy H. Sarma.

Therapeutic potential of quinazoline derivatives for Alzheimer's disease: A comprehensive review.

Quinazolines are considered as a promising class of bioactive heterocyclic compounds with broad properties. Particularly, the quinazoline scaffold has an impressive role in the design and synthesis of new CNS-active drugs. The drug-like properties and pharmacological characteristics of quinazoline could lead to different drugs with various targets. Among CNS disorders, Alzheimer's disease (AD) is a progressive neurodegenerative disorder with memory loss, cognitive decline and language dysfunction. AD is a complex and multifactorial disease therefore, the need for finding multi-target drugs against this devastative disease is urgent. A literature survey revealed that quinazoline derivatives have diverse therapeutic potential for AD as modulators/inhibitors of ß-amyloid, tau protein, cholinesterases, monoamine oxidases, and phosphodiesterases as well as other protective effects. Thus, we describe here the most relevant and recent studies about anti-AD agents with quinazoline structure which can further aid the development and discovery of new anti-AD agents.

Type II c-Met inhibitors: molecular insight into crucial interactions for effective inhibition.

The c-Met tyrosine kinase plays an important role in human cancers. Preclinical studies demonstrated that c-Met is over-expressed, mutated and amplified in a variety of human tumor types and design of more potent c-Met inhibitors is a priority. In this study, 14 molecular dynamics simulations of potent type II c-Met inhibitors were run to resolve the critical interactions responsible for high affinity of ligands towards c-Met considering the essential flexibility of protein-ligand interactions. Residues Phe1223 and Tyr1159, involved in pi-pi interactions were recognized as the most effective residues in the ligand binding in terms of binding free energies. Hydrogen bond interaction with Met1160 was also found necessary for effective type II ligand binding to c-Met.

Phenanthrotriazine Derivatives Containing Arylidine Hydrazone Moieties as Novel Potential c-Met Inhibitors with Anticancer Effect.

Cancer is the second cause of death in the world and the discovery of novel anticancer agents is of vital importance to provide better therapeutic options for cancer patients. In this study, a new series of 12 arylidene hydrazone phenanthrotriazine derivatives were designed, synthesized, and tested in-vitro for antiproliferative activity against three cancer cell lines including colorectal cancer (HT-29), breast cancer (MCF-7) and leukemia (MOLT-4) cells and also against Vero normal cells. The effect of derivatives on cell cycle and apoptosis induction were studied by flow cytometric propidium iodide/RNase assay and Hoechst 33258 staining, respectively, while docking analysis was used to investigate the interactions of synthesized derivatives with the c-Met receptor kinase domain. Some compounds showed considerable antiproliferative activity against tested cancer cells. The most potent derivative was 9k bearing pyrrole moiety with IC50 values of 14.3, 4.7 and 1.7 µM against HT-29, MCF-7 and MOLT-4 cells, respectively, while it showed negligible activity against Vero normal cells (IC50: 95.4 µM). Derivatives bearing 2-nitrophenyl (9g), 4-cyanophenyl (9j), pyrrole (9k), and thiophene (9l) moieties induced G0/G1 cell cycle arrest and also apoptosis at higher doses in MCF-7 cells. Docking study showed that the phenanthrotriazine backbone form H-bond interactions with Asn1209, while phenyl moieties of the pendants generate different hydrophobic interactions with the Asp1164 and Asp1231 residues of c-Met. In conclusion, phenanthrene 1,2,4-triazines, especially the ones with less influence on normal cells, may constitute promising compounds for the discovery of antiproliferative agents with potential c-Met inhibitory capacity.

Design and Synthesis of Novel 1-hydroxy-2,4,5-triaryl Imidazole Derivatives as Anti-cytokine Agents.

Among recent advances in the identification of anti-inflammation agents, anti-cytokines (like Interleukin-1), related to p38 MAPK families play an important role; Here in we designed new effective and low toxic anti-cytokine agents based on 1-hydroxy-2,4,5-triaryl imidazole derivatives. The reaction of oximoinoketone intermediate with ten different aromatic aldehyde and ammonium acetate in refluxing acetic acid condition give imidazole derived product, the IL-1ß inhibitory assay were performed on Human PBMCs (peripheral blood mononuclear cells) using an enzyme-linked immunosorbent assay (ELISA) kit and then in computational part the binding mode of the best compound was accomplished by docking in Crystal structure of p38 MAP kinase (PDB ID: 1A9U) compared with SB202190 as standard drug. All compounds were synthesized and evaluated in biological assay showing the inhibitory activity from 28% to 82% compared to SB202190 and binding mode analysis revealed that the hydrogen-bond interactions with residues (Met109, Val30) were key point in inhibitor binding. Compound 5g clearly proved the best inhibitory action and could be further utilized for designing newer anti-cytokine agents and p38α MAP kinase potentially inhibitory action.

N-Cyclohexylimidazo[1,2-a]pyridine derivatives as multi-target-directed ligands for treatment of Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia. While drugs that target several pathways underlying AD have been proposed, effective treatments remain to be discovered. BACE1, an enzyme associated with AD progression, is a promising target for developing anti-Alzheimer drugs. To find novel multifunctional anti-Alzheimer agents, we designed and synthesized a series of new substituted benzyl-1H-1,2,3-triazol-4-yl-N-cyclohexylimidazo[1,2-a]pyridin-3-amine. The in vitro screening results revealed that most of the compounds exhibited moderate to potent BACE1 and BuChE inhibitory and antioxidant activities. Compounds 7f and 7g, bearing dichloro (2,3-Cl2 and 3,4-Cl2) moieties on the benzyl pendant were selected as the most active compounds in our BACE1 inhibitory assay with respective IC50 values of about 12 and 8.9 µM. In addition, compounds 7g and 7h (4-bromo derivative) showed the highest BuChE inhibitory activity with IC50 of 3.2 and 2.5 µM, respectively. Compound 7g also possessed antioxidant activity with an IC50 value of 10.2 µM and metal chelation potential. Moreover, docking studies were performed to investigate the possible mechanism of inhibition. Taken together, we demonstrate that N-cyclohexylimidazo[1,2-a]pyridine containing triazole motif derivatives deserve further investigation for anti-Alzheimer drug development.

Phenoxyethyl Piperidine/Morpholine Derivatives as PAS and CAS Inhibitors of Cholinesterases: Insights for Future Drug Design.

Acetylcholinesterase (AChE) catalyzes the conversion of Aß peptide to its aggregated form and the peripheral anionic site (PAS) of AChE is mainly involved in this phenomenon. Also catalytic active site (CAS) of donepezil stimulates the break-down of acetylcholine (ACh) and depletion of ACh in cholinergic synapses are well established in brains of patients with AD. In this study, a set of compounds bearing phenoxyethyl amines were synthesized and their inhibitory activity toward electric eel AChE (eeAChE) and equine butyrylcholinesterase (eqBuChE) were evaluated. Molecular dynamics (MD) was employed to record the binding interactions of best compounds against human cholinesterases (hAChE and hBuChE) as well as donepezil as reference drug. In vitro results revealed that compound 5c is capable of inhibiting eeAChE activity at IC50 of 0.50 µM while no inhibitory activity was found for eqBuChE for up to 100 µM concentrations. Compound 5c, also due to its facile synthesis, small structure and high selectivity for eeAChE would be very interesting candidate in forthcoming studies. The main interacting parts of compound 5c and compound 7c (most potent eeAChE and eqBuChE inhibitors respectively) with receptors which confer selectivity for AChE and BuChE inhibition were identified, discussed, and compared with donepezil's interactions. Also during MD simulation it was discovered for the first time that binding of substrates like donepezil to dual CAS and PAS or solely CAS region might have a suppressive impact on 4-α-helical bundles near the tryptophan amphiphilic tetramerization (WAT) domain of AChE and residues which are far away from AChE active site. The results proposed that residues involved in donepezil interactions (Trp86 and Phe295) which are located in CAS and mid-gorge are the mediator of conformational changes in whole protein structure.

Structure based design and anti-breast cancer evaluation of some novel 4-anilinoquinazoline derivatives as potential epidermal growth factor receptor inhibitors.

Quinazoline is one of the most widespread scaffolds amongst natural and synthetic bioactive compounds. Recently the quinazoline derivatives and in particular the 4-anilinoquinazolines have attracted much attention for their anticancer properties due to their capability to stabilize the kinase activity of epidermal growth factor receptor (EGFR). A series of fifteen previously designed and synthesized 4-anilinoquinazoline analogs (4-18) were evaluated for cytotoxic activity on two breast cancer cell lines (MCF-7 and MDA-MB-468). Ligand efficiency and binding mode studies were also done and evaluated for their potentially EGFR inhibitory effects in comparison with imatinib and erlotinib as reference drugs. Among the tested 4-anilinoquinazolines, compound 11 , which contains diethoxy at phenyl ring and morpholino pendants at positions 5 and 7 of the quinazoline ring, demonstrated the most potent biological activity on both cell lines. Our new quinazoline derivatives with different substituents such as cyclic or linear ethers and flour groups may be a promising cytotoxic lead compounds for further anti-breast cancer research.

Synthesis and biological evaluation of quinazolinone-based hydrazones with potential use in Alzheimer's disease.

Discovering multifunctional agents for the treatment of Alzheimer's disease (AD) is an attractive therapeutic approach. BACE1 (ß-site amyloid precursor protein cleaving enzyme 1) inhibitors may play a pivotal role in treating AD. Therefore, the discovery of novel non-peptide BACE1 inhibitors with desirable blood brain barrier permeability is a favorable approach for treatment. Moreover, the antioxidant potential of a drug could serve as an added value for designing dual-acting therapeutic agents. Here, we report the design, synthesis and biological evaluation of quinazolinone-hydrazone derivatives as new multi-target candidates for the treatment of AD. The compounds were investigated for their in vitro BACE1 inhibitory potential using a FRET-based enzymatic assay and also screened for antioxidant activity using DPPH. Among them, compound 4h bearing a 2,3-dichlorophenyl moiety showed the highest activity with an IC50 value of 3.7µM against BACE1. In addition, compound 4i with a 2,4-dihydroxyphenyl scaffold demonstrated moderate BACE1 inhibitory activity (IC50=27.6µM) with a significant antioxidant effect (IC50=8.4µM). Furthermore, docking studies revealed strong interaction between compound 4h and the key residues of BACE1 active site. These results demonstrate that quinazolinone-hydrazone derivatives represent a valuable scaffold for the discovery of novel non-peptidic BACE1 inhibitors.

Multi-structure docking analysis of BACE1 crystal structures and non-peptidic ligands.

In order to design novel non-peptidic inhibitors of BACE1, many research groups have attempted using computational studies including docking analyses. Since there are too many 3D structures for BACE1 in the protein database, the selection of suitable crystal structures is a key prerequisite for the successful application of molecular docking. We employed a multi-structure docking protocol. In which 615 ligands' structures were docked into 150 BACE1 structures. The large number of the resultant docking scores were post-processed by different data analysis methods including exploratory data analysis, regression analysis and discriminant analysis. It was found that using one crystal structure for docking did not result in high accuracy for predicting activity of the BACE1 inhibitors. Instead, using of the multi-structural docking scores, post-processed by chemometrics methods arrived to highly accurate predictive models. In this regards, the PDB accession codes of 4B70, 4DVF and 2WEZ could discriminate between active and inactive compounds, with higher accuracy. Clustering of the BACE1 structures based on principal component analysis of the crystallographic structures the revealed that the discriminant structures are in the center of the clusters. Thus, these structures can be selected as predominant crystal structures for docking studies of non-peptidic BACE1 inhibitors.