Synthesis,pharmacological evaluation,and molecular modeling studies of novel isatin hybrids as potential anticancer agents

A novel series of isatin hybrids 5a-g was designed, synthesized, and characterized spectroscopically. The synthesized compounds were evaluated for their cytotoxic activity against the human breast cancer cell line (MCF-7) by in vitro MTT assay. Amongst the tested compounds, 5e compound bearing benzyl moiety at N₄ piperazine was found to be the most active with the promising IC₅₀ (12.47 µM). Moreover, the active compounds 5e and 5g were subjected to antitumor evaluation (in vivo) against Dalton’s ascitic lymphoma (DAL) cell line and the results suggested that the best active compound 5e can normalize the blood picture in comparison to the standard drug. An in silico molecular docking study using the crystal structure of Hsp90 protein described the role of significant protein–ligand interactions and revealed more insights into the binding mode. The drug-likeliness of the compounds was predicted based on Lipinski's rule of five and pharmacokinetic ADME parameters. Hence, the synthesized isatin hybrids could be novel starting point anticancer lead compounds demonstrating drug-like properties which can be explored further for anticancer drug discovery.     

[Et3NH][HSO4]-mediated efficient synthesis of novel xanthene derivatives and their biological evaluation

A series of novel 2-chloro quinoline incorporated xanthene derivatives were synthesized by using various 2-chloro 3-formyl quinoline, dimedone and triethylammonium hydrogen sulfate [Et₃NH][HSO₄] as a catalyst as well solvent to give good to excellent yields. All the xanthene compounds were investigated for their in vitro antimycobacterial activity against M. tuberculosis H37Ra (MTB) and M. bovis BCG strains. Among the synthesized compounds 3a, 3c, 3d, 3e, 3g, 3h and 3k were highly potent against both the strains. Most of the active compounds were non-cytotoxic against THP-1, HCT-116, A549 and MCF-7 cell lines. Most active compounds were having higher selectively index which suggested that these compound were highly potent.     

Synthesis,biological evaluation and Structure Activity Relationships (SARs) study of 8-(substituted)aryloxycaffeine

A series of 8-(substituted)aryloxycaffeine were prepared from 8-bromocaffeine and (substituted)phenols by modified Ullmann reaction. In vitro antibacterial activity, inhibitory activity on topoisomerase II and pharmacological activities were evaluated for the synthesized 8-(substituted)aryloxycaffeine. Among the synthesized compounds, 8-(5-chloropyridin-3-yloxy)caffeine (3k) showed strong inhibitory activity (MIC = 15.6 μg/mL) against the tested gram negative (−) bacteria Salmonella enteritidis. 8-(quinolin-8-yloxy)caffeine (3g) showed the strongest inhibitory activity against topoisomerase II. And the compounds 8-(6-methylpyridin-2-yloxy)caffeine (3j) and 8-(3-chloro-6-(trifluoromethyl)pyridin-2-yloxy)caffeine (3m) showed analgesic effect without the central nervous system stimulation.     

Molecular modelling,synthesis, and antimalarial potentials of curcumin analogues containing heterocyclic ring

The molecular modelling approach was applied to a series of nineteen curcumin analogues to find the possible PfRIO2 kinase inhibitory action. A putative active site in flexible loop (S1) of PfRIO2 kinase was explored computationally to recognize the molecular basis of ligands binding. The ligands (curcumin analogues; 3a–3s) were well accommodated in the selected active site (S1) due to their higher molecular size and length. Further all these synthesized compounds (3a–3s) were evaluated for their in vitro antimalarial activity according to the reported method. The antimalarial data showed that all these compounds to have parasiticidal activity with minimum killing concentrations (MKCs) range between 3.87 and 25.35 μM and schizonticidal activity with IC₅₀ range between 1.48 and 23.09 μM. The compound 3p showed the most significant result with maximum schizonticidal (IC₅₀; 1.48 ± 0.10 μM) and parasiticidal activities (MKC; 3.87 ± 0.36 μM) could be identified as promising lead for further investigations.     

Synthesis,biological evaluation and molecular docking studies of novel benzimidazole derivatives

A novel series of N-substituted-benzimidazolyl linked para substituted benzylidene based molecules containing three pharmacologically potent hydrogen bonding parts namely; 2,4-thiazolidinedione (TZD: a 2,4-dicarbonyl), diethyl malonate (DEM: a 1,3-diester and an isooxazolidinedione analog) and methyl acetoacetate (MAA: a β-ketoester) (6a–11b) were synthesized and evaluated for in vitro α-glucosidase inhibition. The structure of the novel synthesized compounds was confirmed through the spectral studies (LC–MS, ¹H NMR, ¹³C NMR, FT-IR). Comparative evaluation of these compounds revealed that the compound 9b showed maximum inhibitory potential against α-amylase and α-glucosidase giving an IC₅₀ value of 0.54 ± 0.01 μM. Furthermore, binding affinities in terms of G score values and hydrogen bond interactions between all the synthesized compounds and the AA residues in the active site of the protein (PDB code: 3TOP) to that of Acarbose (standard drug) were explored with the help of molecular docking studies. Compound 9b was considered as promising candidate of this series.     

Synthesis,anticancer activity,toxicity evaluation and molecular docking studies of novel phenylaminopyrimidine—(thio)urea hybrids as potential kinase inhibitors

Thirty-two novel urea/thiourea compounds as potential kinase inhibitor were designed, synthesized and evaluated for their cytotoxic activity on breast (MCF7), colon (HCT116) and liver (Huh7) cancer cell lines. Compounds 10, 19 and 30 possessing anticancer activity with IC₅₀ values of 0.9, 0.8 and 1.6 μM respectively on Huh7 cells were selected for further studies. These hit compounds were tested against liver carcinoma panel. Real time cell electronic sensing assay was used to evaluate the effects of the compounds 10, 19 and 30 on the growth pattern of liver cancer cells. Apoptotic cell death and cell cycle analysis upon treatment of liver carcinoma cells with hit compounds were determined. A significant apoptotic cell death was detected upon treatment of Huh7 and Mahlavu cells with compound 30 after 48 h of treatment. Additionally, compound 10 caused cell cycle arrest at G0/G1 phase. Mutagenicity of hit compounds was evaluated. Assertively, these compounds were not found to be mutagenic on Salmonella typhimurium strains TA98 and TA100. To understand the binding modes of the synthesized compounds, molecular docking studies were performed using the crystal data of VEGFR and Src-kinase enzymes in correlation with anticancer activities.     

Design,DFT studies,antimicrobial and antioxidant potential of Binuclear N-heterocyclic Carbene (NHCs) complexes,Probing the aspect of DNA interaction through In-vitro and In-silico approach

N-heterocyclic carbene (NHC) adducts have shown remarkable biological potential for numerous medical applications. With an aim to improve biological potential of benzimidazolium salts, newer analogues of benzimidazole and their silver complexes were synthesized and characterized. Synthesized salts (L₁-L₂) and silver complexes (C₁-C₂) were confirmed through elemental analysis, UV–visible spectroscopy, FTIR, ¹H NMR & ¹³C NMR spectroscopy. The compounds C1 & C2 were found stable in solution form for studied time period when examined spectroscopically and showed optimum lipophilicity when measured for their partition coefficient through flask shake method. Synthesized compounds showed good antimicrobial potential against gram positive bacterial strain S. Aureus with IC₅₀ 2.02±0.12 and 2.11±0.13 µM respectively while 2.11±0.1 and 2.28±0.17 µM against gram negative bacterial strain E. Coli for C1 and C2 respectively. The interaction study of the related compounds with DNA was predicted by molecular docking study, which confirmed that the studied compound C1 (-8.04 kcal/mol) has a higher binding energy than compound C2 (-4.23 kcal/mol); Also, the compound C1 exhibits a better affinity against to DNA than Ethidium bromide (-7.68 kcal/mol) and cisplatin (-6.21 kcal/mol).The claim was practically assured through spectroscopic and viscometeric method which confirmed that compounds have good affinity for DNA with binding constant kb, 5.78×10⁴ M^-1 and 6.84×10⁴ M^-1 for C1 and C2 respectively.     

Synthesis of formazans from Mannich base of 5-(4-chlorophenyl amino)-2-mercapto-1,3,4-thiadiazole as antimicrobial agents

5-(4-Chlorophenyl amino)-2-mercapto-1,3,4-thiadiazole (I) was refluxed with formaldehyde and ammonium chloride in ethanol yielding the Mannich base 5-(4-chloro phenyl amino)-3-aminomethyl-2-mercapto-1,3,4-thiadiazole (II). Esterification with 4-chloro-(2,6-dinitro phenoxy)-ethyl acetate (III) under anhydrous conditions gave the intermediate (IV). Subsequent hydrazinolysis with hydrazine hydrate gave the corresponding hydrazide 3-amino methyl-5-(4-chloro phenyl amino)-2-mercapto-4′-(2′,6′-dinitro phenoxy)-acetyl hydrazide (V). The hydrazide was converted into the Schiff bases (VI_a–b) by reacting with 2-chlorobenzaldehyde and 3-methoxy-4-hydroxy benzaldehyde in presence of methanol containing 2–3 drops of acetic acid. Diazotisation with aromatic amines, sulphanilic acid and sulphur drugs gave the formazans (VII_a–g) respectively. Chemical structures have been established by elemental analysis and the spectral techniques of FTIR, ¹H NMR and mass. Antimicrobial activity (in vitro) was evaluated against the two pathogenic bacterial strains. Escherichia coli and Salmonella typhi, three fungal strains Aspergillus niger, Penicillium species and Candida albicans. The compounds have shown moderate activity.     

Synthesis and antimicrobial activity of Schiff bases and 2-azetidinones derived from quinazolin-4(3H)-one

A series of 2-oxo-azetidinyl-quinazolin-4(3H)-ones 5a–k have been synthesized from Schiff bases 4a–k. Schiff bases were synthesized by the condensation reaction of compound 3 with substituted aromatic aldehydes. The benzoxazinone 2 was prepared by the cyclization reaction of acid chloride 1 with 5-bromo anthranilic acid. Further reaction of benzoxazinone 2 with hydrazine hydrate yielded compound 3. The structures of the synthesized compounds were elucidated on the basis of elemental analyses as well as IR and NMR spectral data. Schiff bases 4a–k and 2-azetidinones 5a–k were screened for antibacterial and antifungal activities in vitro. Compounds having chloro and methoxy groups exhibited good antimicrobial activity.     

Design,synthesis and biological evaluation of quinazolin-4(3H)-one Schiff base conjugates as potential antiamoebic agents

In an effort to develop novel antiamoebic scaffolds having better efficacy than the standard drug metronidazole (IC₅₀ = 1.80 μM) used against Entamoeba histolytica, quinazolin-4(3H)-one Schiff base conjugates were synthesized and evaluated against HM1: IMSS strain of E. histolytica. Out of the thirteen compounds (S2-S14), six compounds (S2, S3, S4, S5, S6 and S11) were found to be better inhibitors than metronidazole and showed low cytotoxicity on HeLa cells, a cervical cancer cell line. The structure of intermediate compound S1 was confirmed by crystal structure studies.     

On the thermal decomposition pathway of coordination compounds: synthesis,crystal structures and properties of new polymorphic CuI(2-ethylpyrazine) coordination compounds

Five new coordination compounds were prepared at room temperature in solution, under solvothermal conditions at elevated temperatures or by thermal decomposition reactions. In the amine rich 1:2 compound [(CuI)₂(2-ethylpyrazine-N)₄] (I) discrete molecular complexes are found that consist of (CuI)₂ dimers in which each copper atom is coordinated by two 2-ethylpyrazine ligands. The crystal structure of the 1:1 compound poly[(CuI)₂(μ₂-2-ethylpyrazine-N,N′)₂] (II) contains (CuI)₂ dimers which are connected by the 2-ethylpyrazine ligands into layers parallel to (010). The second modification of a 1:1 compound poly[(CuI)₂(μ₂-2-ethylpyrazine-N,N′)-(2-ethylpyrazine-N)] (III) consists of 8-membered CuI rings, which are connected by the 2-ethylpyrazine ligands into layers. In one modification of poly[(CuI)₂(μ₂-2-ethylpyrazine-N,N′)] (IV) CuI double chains are connected by the ligands into layers parallel to (001). If the preparation is kinetically controlled, crystals of the second modification poly[(CuI)₂(μ₂-2-ethylpyrazine)-N,N′]] (V) can be obtained. The crystal structure of V is very similar to that of compound IV, with the main difference that the orientation of the ethyl groups of the 2-ethylpyrazine ligands is different. The thermal reactivity of all compounds as well as the thermodynamic stability and the transformation behaviour of the polymorphic modifications were investigated using DTA-TG-MS and DSC measurements, temperature resolved X-ray powder diffraction as well as temperature dependent crystallisation experiments. The occurrence of the different phases is discussed and the results are compared with those obtained on the corresponding CuCl and CuBr compounds on the basis of preparative results and density-functional calculations.     

Dioxacyclophanes as a Scaffold for Silicon-based Circularly Polarized Luminescent Materials

Planar chiral dioxacyclophanes were designed and synthesized as a key scaffold for materials with circularly polarized luminescence (CPL). Representative planar chiral 1,12-dioxa[12](1,4)naphthaleneophane-derived organosilane compounds (?)-(R)-1, (+)-(R)-2, and (?)-(R)-3 were prepared by (+)-sparteine-mediated aryl metalation and an electrophilic reaction with chlorosilanes. The absolute configurations of the planar chirality were determined in the R form by single-crystal X-ray analysis. Optically active compound (+)-(R)-2 exhibited blue fluorescence and a CPL signal with a dissymmetry factor (g_lum value) of 0.001 in solution. The electronic structure was corroborated by DFT and TD-DFT calculations rationalizing the observed spectroscopic properties.     

Mononuclear and dinuclear iron(III) compounds with β-diketonate ligands: Synthesis,magnetic behavior and DFT calculations

The synthesis, crystal structure, magnetic properties and DFT calculations of two low-nuclearity Fe(III) compounds based on β-diketonate ligand, [Fe(OMe)(BTA)₂]₂ (1) and Fe(BTA)₃ (2) (BTA = 4,4,4-trifluoro-1-phenyl-2,4-butanedione) are reported. Compound (1) is a molecular dimer in which Fe(III) ions are coordinated to two BTA ligands and bridged by two methoxide anions, while compound (2) is a trischelated Fe(III) monomer. Magnetic measurements revealed antiferromagnetic interactions in both compounds. In (1) the magnetic coupling is intramolecular, whereas in (2) it occurs via intermolecular interactions as a result of π–π stacking between the phenyl rings. DFT calculations using the broken symmetry approach were carried out to obtain the theoretical coupling constant value for both compounds and to rationalize the pathway for magnetic interactions in (2).     

Composés á structure imidazopyridinyl-arylpropénone,nouveaux agents anti-infectieux potentiels

This paper describes the design by juxtaposition of anti-infectious moieties, a series of hybrid imidazopyridinyl-arylpropenone compounds. These compounds (5a–y) were synthesized by a crotonization reaction of 1-(2-methylimidazo[1,2-a]pyridin-3-yl)ethanone (3) with benzaldehyde derivatives (4). Spectral determination of structure of those compounds was performed by NMR and ESI mass spectroscopy. From the screening of antiparasitic and antimicrobial activities, the compound 5q (IC₅₀ = 1.52 μM) was identified for possible development against a chloroquine-resistant strain of Plasmodium falciparum. The compounds 5n, 5s and 5w showed a veterinary interest due to their nematicidal activities (LC₁₀₀) against Haemonchus contortus from 7.1 to 1.5 nM. Against candidiasis, three other compounds (5e, 5g, 5v) inhibited drug-resistant strains of Candida albicans (MIQ = 1.25 to 0.31 μg). This study showed that the arylpropenone functional group vectorised by imidazopyridine could be considered as a new pharmacophore with potential anti-infectious activities.     

Synthesis,In Silico Studies,and Evaluation of Syn and Anti Isomers of N-Substituted Indole-3-carbaldehyde Oxime Derivatives as Urease Inhibitors against Helicobacter pylori

Gastrointestinal tract infection caused by Helicobacter pylori is a common virulent disease found worldwide, and the infection rate is much higher in developing countries than in developed ones. In the pathogenesis of H. pylori in the gastrointestinal tract, the secretion of the urease enzyme plays a major role. Therefore, inhibition of urease is a better approach against H. pylori infection. In the present study, a series of syn and anti isomers of N-substituted indole-3-carbaldehyde oxime derivatives was synthesized via Schiff base reaction of appropriate carbaldehyde derivatives with hydroxylamine hydrochloride. The in vitro urease inhibitory activities of those derivatives were evaluated against that of Macrotyloma uniflorum urease using the modified Berthelot reaction. Out of the tested compounds, compound 8 (IC₅₀ = 0.0516 ± 0.0035 mM) and compound 9 (IC₅₀ = 0.0345 ± 0.0008 mM) were identified as the derivatives with potent urease inhibitory activity with compared to thiourea (IC₅₀ = 0.2387 ± 0.0048 mM). Additionally, in silico studies for all oxime compounds were performed to investigate the binding interactions with the active site of the urease enzyme compared to thiourea. Furthermore, the drug-likeness of the synthesized oxime compounds was also predicted.     

Novel quinazolin-4(3H)-one derivatives containing a 1,3,4-oxadiazole thioether moiety as potential bactericides and fungicides: Design,synthesis, characterization and 3D-QSAR analysis

A series of quinazolin-4(3H)-one derivatives containing a 1,3,4-oxadiazole thioether moiety were designed, synthesized and evaluated for their biological activities against phytopathogenic microorganisms. Antimicrobial bioassays in vitro indicated that most of the target compounds exhibited more significant antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo) than the agricultural bactericide thiadiazole-copper. A comparative molecular similarity index analysis (CoMSIA) model with cross-validated q² and non-cross-validated r² values of 0.561 and 0.882 was generated to investigate the structure-activity relationships of title compounds against Xoo. Title compound 6w, which was rationally designed under the guidance of obtained CoMSIA model, exhibited the excellent anti-Xoo effect in vitro with an EC₅₀ value of 29.10 μg/mL, which is approximately 3-folds more effective than thiadiazole-copper (113.93 μg/mL). In addition, compound 6i demonstrated the impressive antifungal effects against Rhizoctonia solani (Rs) and Fusarium graminearum (Fg) in vitro, with the corresponding EC₅₀ values of 11.01 μg/mL and 36.00 μg/mL, which is obviously better than the agricultural fungicide hymexazol (76.74 μg/mL and 56.19 μg/mL, respectively). The above researches indicate that quinazolin-4(3H)-one derivatives containing a 1,3,4-oxadiazole thioether moiety could be further studied as template molecules of novel agricultural microbicides.     

Synthesis of 1,3-dithiolane-containing nitromethene compounds and their biological activity as insecticides

1,3-Dithiolane-containing nitromethylene derivatives, as candidates for screening as neonicotinoid insecticides, were synthesized by reaction of compound (4) with 1,2-ethanedithiol. Compounds 7a–g were obtained via Mannich reaction of (E)-1-((1,3-dithiolan-2-yl)methyl)-2-(nitromethylene)imidazolidine (6), primary amines and formaldehyde. The synthesized compounds were identified by ¹H NMR, IR spectroscopy and elemental analysis. Preliminary bioassays indicated that most of the compounds had moderate insecticidal activity against Aphis craccivora. The relationship between molecular structure and biological activity is discussed.     

Emericelactones A-D: Four novel polyketides produced by Emericella sp. XL 029, a fungus associated the leaves of Panax notoginseng

The application of an OSMAC approach on an endophytic fungus Emericella sp. XL 029 has yielded four novel polyketides, emericelactones A-D (1–4).The structures and stereochemistry of 1–4 were elucidated by NMR and MS data analyses, computational methods, as well as by comparison with known compounds. Compound 1 contained an unprecedented linear pentaene substructure ending in an oxabicyclo[2.2.1]heptane moiety, while compounds 2–4 are epimers possessing an unprecedented linear triene structures ending in two cyclic moieties of an oxabicyclo[2.2.1]heptane and a cyclopentan-1-one. Compounds 1–4 showed moderate antimicrobial activities against three agricultural pathogenic fungi (Verticillium dahliae Kleb, Rhizoctonia solani and Gibberella saubinetii) and two human pathogenic bacteria (Micrococcus lysodeikticus and Salmonella typhi) with MIC values of 25–50?μg/mL.     

Synthesis,characterization, biological screening and molecular docking of Zn(II) and Cu(II) complexes of 3,5-dichlorosalicylaldehyde-N4-cyclohexylthiosemicarbazone

A 3,5-dichlorosalicylaldehyde-N⁴-cyclohexylthiosemicarbazone (C₁₄H₁₆Cl₂N₃OS) and its complexes [Zn(dsct)(phen)]·DMF ( 1 ), [Zn(dsct)(bipy)]·DMF ( 2 ), [Cu(dsct)(bipy)]·DMF ( 3 ) (phen = 1,10-phenathroline, bipy = 2,2’bipyridine) were synthesized and characterized by CHN analysis, FT-IR, UV–vis and NMR spectra. The molecular structure of the thiosemicarbazone (H₂dsct) and its complexes have been resolved using single crystal XRD studies. In the complexes, thiosemicarbazone exist in the thioiminolate form and acts as dideprotonated tridentate ligand coordinating through phenolic oxygen, thioiminolate sulfur and azomethine nitrogen. The antibacterial activity of the prepared compounds were screened against Escherichia coli, Salmonella typhi, Enterobacter aerogenes, Shigella dysentriae, Bacillus cereus, Staphylococcus aureus. All the complexes showed activity against bacterial strains E.coli and Salmonella typhi. The thiosemicarbazone showed activity against three bacterial strains such as E. coli, Enterobacter aerogenes and Shigella dysentriae. Complex 2 showed very good antibacterial activity as compared to standard drug (Ampicillin) against the bacterial strain, Salmonella typhi. Finally, the thiosemicarbazone and its complexes have been used to accomplish molecular docking studies against an Epidermal Growth Factor Receptor (EGFR) and breast cancer mutant 3hb5-oxidoreductase to determine the most preferred mode of interaction. The results confirm that the complex [Cu (dsct)(bipy)]·DMF( 3 ) showed the highest docking score as compared to other complexes under study. The [Cu(dsct)(bipy)]·DMF( 3 ) complex was evaluated for their anticancer activities against breast cancer cell line (MCF-7) and normal L929 (Mouse Fibroblast) cell line. It was found that the compound showed an LC₅₀ of 6.25 μg/mL against breast cancer cell line (MCF-7).