Synthesis and cytotoxic activity of novel poly-substituted imidazo[2,1- $$c$$ c ][1,2,4]triazin-6-amines

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.

Discovery of anticancer agents with c-Met inhibitory potential by virtual and experimental screening of a chemical library

c-Met receptor tyrosine kinase has recently emerged as an important target with therapeutic implications in pancreatic cancer. In this study, we carried out a docking virtual screening on an in-house library of 441 synthesized compounds and selected the compounds with the best interactions with the c-Met protein to be subjected to experimental tests. Ten compounds belonging to 3 different classes of chemical structures were selected for this purpose and their antiproliferative effects were studied against 4 pancreatic ductal adenocarcinoma (PDAC) cell lines including AsPC-1, Suit-2, Panc-1 and Mia-Paca-2 cells, primary PDAC cells and also c-Met amplified EBC-1 cell line by sulforhodamine-B assay. Apoptosis induction was examined by Hoechst 33258 staining and annexin V-FITC/propidium iodide flow cytometric assay. The best compound was also assayed in three-dimensional cultures of AsPC-1 cells and its c-Met inhibitory potential was studied by immunoblotting and a homogenous time resolved fluorescence (HTRF) assay. The compound with a phenanthrotriazine hydrazinyl scaffold bearing nitrophenyl pendant (PhTH) was the most active derivative, with IC50 values in the range of 5-8 μM. This compound exerted antiproliferative effect against AsPC-1 cells also in the presence of hepatocyte growth factor (HGF). PhTH induced apoptosis, dose-dependently inhibited spheroid growth, inhibited c-Met activity in cell-free HTRF assay and also inhibited the phosphorylation of c-Met and its downstream effector ERK1/2 in AsPC-1 cells. Molecular docking and dynamics simulation and MM-PBSA analysis confirmed close interactions of PhTH with c-Met kinase domain. Some of the tested compounds in this study seem to be potential c-Met inhibitors with promising activities against PDAC cells.

Novel 5-Nitrofuran-Tagged Imidazo-Fused Azines and Azoles Amenable by the Groebke–Blackburn–Bienaymé Multicomponent Reaction: Activity Profile against ESKAPE Pathogens and Mycobacteria

A chemically diverse set of 13 5-nitrofuran-tagged heterocyclic compounds has been prepared via the Groebke–Blackburn–Bienaymé multicomponent reaction. The testing of these compounds against the so-called ESKAPE panel of pathogens identified an apparent lead compound—N-cyclohexyl-2-(5-nitrofuran-2-yl)imidazo[1,2-a]pyridine-3-amine (4a)—which showed an excellent profile against Enterobacter cloacae, Staphylococcus aureus, Klebsiella pneumoniae, and Enterococcus faecalis (MIC 0.25, 0.06, 0.25 and 0.25 µg/mL, respectively). Its antibacterial profile and practically convenient synthesis warrant further pre-clinical development. Certain structure-activity relationships were established in the course of this study which were rationalized by the flexible docking experiments in silico. The assessment of antitubercular potential of the compounds synthesized against drug sensitive H37v strain of Mycobacterium tuberculosis revealed little potential of the imidazo-fused products of the Groebke–Blackburn–Bienaymé multicomponent reaction as chemotherapeutic agents against this pathogen.

Design, synthesis, and biological evaluation of imidazopyridine-linked thiazolidinone as potential anticancer agents

In this study, two series of imidazopyridine-linked thiazolidinone rings (5a-h and 6a-h) constituting 16 new compounds were synthesized and tested for their antiproliferative activity against a panel of three human cancer cell lines, that is, MCF-7 (human breast cancer), A549 (human lung cancer), and DU145 (human prostate cancer). Three compounds, 5h, 6f, and 6h, exhibited remarkable results against all three cell lines, but compound 6h was found to be the most active one against the breast cancer cell line. Among all the synthesized compounds, 6h displayed the highest antioxidant results. Furthermore, the potent compounds 5h, 6f, and 6h showed no signs of toxicity at doses ranging from 50 to 500 mg/kg of animal body weight. The biochemical parameters (SGOT and SGPT) of compound 6h nearly matched the control in hepatotoxicity studies. The molecular docking and MM-GBSADG binding studies are in agreement with the in vitro anticancer and antioxidant activity results. The most promising compound 6h was found to have the highest docking score and binding energy, and its absorption, distribution, metabolism, and excretion (ADME) parameters are in the acceptable range. Thus, it can be concluded that 6h, an imidazopyridine derivative endowed with a thiazolidinone ring system, has the potential to be developed as an anticancer agent.

The status of isocyanide-based multi-component reactions in Iran (2010-2018)

Isocyanides as key intermediates and magic reactants have been widely applied in organic reactions for direct access to a broad spectrum of remarkable organic compounds. Although the history of these magical compounds dates back more than 100 years, it still has been drawing widespread attention of chemists who confirmed their versatility and effectiveness. Because of their wide spectrum of pharmacological, industrial and synthetic applications, many reactions with the utilization of isocyanides are reported in the literature. In this context, Iranian scientist played a significant role in the growth of isocyanides chemistry. The present review article covers literature from the period starting from 2010 onward and encompasses new synthetic routes and organic transformation involving isocyanides by Iranian researchers. During this period, a diverse range of isocyanide-based multi-component reactions (I-MCRs) has been reported such as a new modification of Ugi, post-Ugi, Passerini and Groebke-Blackburn-Bienayme condensation reactions, isocyanide-based [1 + 4] cycloaddition reactions, isocyanide-acetylene-based MCRs, isocyanide and Meldrum's acid-based MCRs, several unexpected reactions besides green mediums and novel catalytic systems for the synthesis of diverse kinds of pharmaceutically and industrially remarkable heterocyclic and linear organic compounds. This review also emphasizes the neoteric applications of I-MCR for the synthesis of valuable peptide and pseudopeptide scaffolds, enzyme immobilization and functionalization of materials with tailorable properties that can play important roles in the plethora of applications.

The Groebke-Blackburn-Bienaymé Reaction

Imidazo[1,2-a]pyridine is a well-known scaffold in many marketed drugs, such as Zolpidem, Minodronic acid, Miroprofen and DS-1 and it also serves as a broadly applied pharmacophore in drug discovery. The scaffold revoked a wave of interest when Groebke, Blackburn and Bienaymé reported independently a new three component reaction resulting in compounds with the imidazo[1,2-a]-heterocycles as a core structure. During the course of two decades the Groebke Blackburn Bienaymé (GBB-3CR) reaction has emerged as a very important multicomponent reaction (MCR), resulting in over a hundred patents and a great number of publications in various fields of interest. Now two compounds derived from GBB-3CR chemistry received FDA approval. To celebrate the first 20 years of GBB-chemistry, we present an overview of the chemistry of the GBB-3CR, including an analysis of each of the three starting material classes, solvents and catalysts. Additionally, a list of patents and their applications and a more in-depth summary of the biological targets that were addressed, including structural biology analysis, is given.

The use of magnetic starch as a support for an ionic liquid-β-cyclodextrin based catalyst for the synthesis of imidazothiadiazolamine derivatives

In this paper, a novel catalyst is introduced based on the introduction of an ionic liquid onto the β-cyclodextrin. The ionic liquid-β-cyclodextrin was anchored to magnetic starch (denoted βCD-IL@M-Starch) and fully characterized by several methods including TEM, TGA, VSM and FT-IR. The catalyst was used for the synthesis of imidazo[2,1-b][1,3,4]thiadiazol-5-amine and imidazo[1,2-a]pyridin-3-amine derivatives. βCD-IL@M-Starch catalyst showed very good activity in the synthesis of diphenylimidazo[2,1-b][1,3,4]thiadiazol-5-amine derivatives from the corresponding benzaldehyde, semicarbazide, benzaldehydes and isocyanides. The products were obtained in a mild reaction conditions in good isolated yields in the presence of βCD-IL@M-Starch as catalyst. The catalyst showed to be magnetically reusable, and gave very good results in 10 sequential reactions.

Synthesis and cytotoxic evaluation of some derivatives of triazole-quinazolinone hybrids

Triazoles and quinazolinones are important heterocyclic structures with diverse biological properties including cytotoxic, antibacterial, antifungal and anticonvulsant activities. Due to valuable cytotoxic effects of both triazole and quinazoline derivatives, in this study a series of quinazolinone-triazole hybrids were synthesized in a multiple-step reaction procedure. 3-Amino-quinazolinone derivatives were treated with chloroacetyl chloride in the presence of dichloromethane/triethylamine to afford 2-chloro -N-(4-oxo-2- quinazolin3 (3H)-yl) acetamide derivatives. The reaction of resultants with 4-mehyl-4-H-1, 2, 4-triazole-3- thiol in dry acetone and potassium carbonate led to the formation of final products. Synthesized compounds were evaluated for their cytotoxic effects against MCF-7 and Hela cell lines using MTT colorimetric assay. Amongst tested compounds, 6a showed the highest cytotoxic activity against MCF7 cell line at all tested concentrations while compounds 6b and 6c indicated mild cytotoxic effects against Hela cell line at highest tested concentration reducing cell viability about 40%. The IC50 values of tested compounds revealed that the MCF-7 is more susceptible to the compound 6a.

Pyrano[3,2-c]quinoline Derivatives as New Class of α-glucosidase Inhibitors to Treat Type 2 Diabetes: Synthesis, in vitro Biological Evaluation and Kinetic Study

BACKGROUND

Pyrano[3,2-c]quinoline derivatives 6a-n were synthesized via simple two-step reactions and evaluated for their in vitro α-glucosidase inhibitory activity.

METHODS

Pyrano[3,2-c]quinoline derivatives 6a-n derivatives were prepared from a two-step reaction: cycloaddition reaction between 1-naphthyl amine 1 and malonic acid 2 to obtain benzo[h]quinoline-2(1H)-one 3 and reaction of 3 with aryl aldehydes 4 and Meldrum's acid 5. The anti- α-glucosidase activity and kinetic study of the synthesized compounds were evaluated using α-glucosidase from Saccharomyces cerevisiae and p-nitrophenyl-a-D-glucopyranoside as substrate. The α-glucosidase inhibitory activity of acarbose was evaluated as positive control.

RESULTS

All of the synthesized compounds, except compounds 6i and 6n, showed more inhibitory activity than the standard drug acarbose and were also found to be non-cytotoxic. Among the synthesized compounds, 1-(2-bromophenyl)-1H-benzo[h]pyrano[3,2-c]quinoline-3,12(2H,11H)-dione 6e displayed the highest α-glucosidase inhibitory activity (IC50 = 63.7 ± 0.5 µM). Kinetic study of enzyme inhibition indicated that the most potent compound, 6e, is a non-competitive inhibitor of α-glucosidase with a Ki value of 72 µM. Additionally, based on the Lipinski rule of 5, the synthesized compounds were found to be potential orally active drugs.

CONCLUSION

Our results suggest that the synthesized compounds are promising candidates for treating type 2 diabetes.

Experimental and computational evidence for KOt-Bu-promoted synthesis of oxopyrazino[1,2-a]indoles

Metal-free intramolecular hydroamination of some Ugi adducts in the presence of KOt-Bu in DMF at room temperature led to the formation of novel oxopyrazino[1,2-a]indole derivatives.