Piperazine-azole-fluoroquinolone hybrids: Conventional and microwave irradiated synthesis,biological activity screening and molecular docking studies

A series of new 1,2,4-triazole and 1,3,4-oxadiazole derivatives was obtained via several steps sequential reactions of phenyl piperazine. Then, these compounds were converted to the corresponding fluoroquinolone hybrids via one pot three component Mannich reaction. All the reactions were examined under conventional and microwave mediated conditions, and optimum conditions were determined. The effect of different solvents and microwave power on microwave prompted reactions was investigated as well. All the newly synthesized compounds were characterized by FTIR, ¹H NMR, ¹³C NMR and EI MS spectral techniques. The antimicrobial activity, DNA gyrase and Topoisomerase IV inhibition potentials were performed. The results obtained showed that fluoroquinolone hybrids possess good antimicrobial activity. Moreover, Fluoroquinolone-azole-piperazine hybrids synthesized in the present study displayed excellent DNA gyrase inhibition. To unveil the interaction mode of compounds to receptor, a molecular docking study was performed. With an average least binding energy of −9.5 kcal/mol, all compounds were found to have remarkable inhibitory potentials against DNA gyrase (E. coli).     

Effect of organic solvents on the activity and stability of halophilic alcohol dehydrogenase (ADH2) from Haloferax volcanii

The effect of various organic solvents on the catalytic activity, stability and substrate specificity of alchohol dehydrogenase from Haloferax volcanii (HvADH2) was evaluated. The HvADH2 showed remarkable stability and catalysed the reaction in aqueous?Corganic medium containing dimethyl sulfoxide (DMSO) and methanol (MeOH). Tetrahydrofuran and acetonitrile were also investigated and adversely affected the stability of the enzyme. High concentration of salt, essential to maintain the enzymatic activity and structural integrity of the halophilic enzyme under standard conditions may be partially replaced by DMSO and MeOH. The presence of organic solvents did not induce gross changes in substrate specificity. DMSO offered a protective effect for the stability of the enzyme at nonoptimal pHs such as 6 and 10. Salt and solvent effects on the HvADH2 conformation and folding were examined through fluorescence spectroscopy. The fluorescence findings were consistent with the activity and stability results and corroborated the denaturing properties of some solvents. The intrinsic tolerance of this enzyme to organic solvent makes it highly attractive to industry.     

Novel Pyrazoloquinolin-2-ones: Design,synthesis, docking studies,and biological evaluation as antiproliferative EGFR-TK inhibitors

Two new series of diethyl 2-[2-(substituted-2-oxo-1,2-dihydroquinolin-4-yl)hydrazono]-succinates 6a-g and 1-(2-oxo-1,2-dihydroquinolin-4-yl)-1H-pyrazoles 7a-f have been designed and synthesized. The structures of the synthesized compounds were proved by IR, mass, NMR (2D) spectra and elemental analyses. The target compounds were evaluated for their in vitro cytotoxic activity against 60 cancer cell lines according to NCI protocol. Consequently, seven compounds were further examined against the most sensitive cell lines, leukemia CCRF-CEM, and MOLT-4. 5-Amino-1-(6-bromo-2-oxo-1,2-dihydroquinolin-4-yl)-1H-pyrazole-3,4-dicarbonitrile (7f) was the most active product, with IC₅₀ = 1.35 uM and 2.42 uM against MOLT-4 and CCRF-CEM, respectively. Also, it showed a remarkable inhibitory activity compared to erlotinib on the EGFR TK with IC₅₀ = 247.14 nM and 208.42 nM, respectively. Cell cycle analysis of MOLT-4 cells treated with 7f showed cell cycle arrest at G2/M phase (supported by Caspases, BAX and Bcl-2 studies) with a significant pro-apoptotic activity as indicated by annexin V-FITC staining. Moreover, the docking study indicated that both the pyrazole moiety and the quinolin-2-one ring showed good fitting into EGFR (PDB code: 1M17). In order to interpret SAR of the designed compounds, and provide a basis for further optimization, molecular docking of the synthesized compounds to known EGFR inhibitors was performed. The study illustrated the effect of several factors on the compounds’ activity.     

Mutagenic activity of methyl-substituted tri-and tetracyclic aromatic sulfur heterocycles

A number of polycyclic aromatic sulfur heterocycles have been identified in coal-derived products and in shale oils. The mutagenic activity of some of these compounds, including dibenzothiophene, benzo[b]naphtho[1,2-d]thiophene, benzo[b]naphtho[2,1-d]thiophene and benzo[b]naphtho[2,3-d]thiophene have been determined using the Salmonella/microsome mutagenicity test. These compounds demonstrated either very weak or no mutagenic activity. The methyl derivatives of each of these four compounds were assayed for mutagenic activity. Salmonella typhimurium TA98 was used as the tester strain. All assays required a rat-liver homogenate metabolic activator. Five of the methylated derivatives, 1-methylbenzo[b]naphtho[1,2-d]thiophene, 3-methylbenzo[b]naphtho[1,2,-d]thiophene, 1-methylbenzo[b]-naphtho[2,1-d]thiophene, 6-methylbenzo[b]naphtho[2,1-d]thiophene and 4-methylbenzo[b]naphtho[2,3-[d]thiophene demonstrated mutagenic activity. However, activity was observed only at high concentrations of the metabolic activator.     

Design and synthesis of novel imidazo[4,5-b]pyridine based compounds as potent anticancer agents with CDK9 inhibitory activity

New imidazo[4,5-b]pyridine derivatives were designed, synthesized and screened for their anticancer activity against breast (MCF-7) and colon (HCT116) cancer cell lines. Nine compounds (I, II, IIIa, IIIb, IV, VI, VIIa, VIII, IX) showed significant activity against MCF-7, while six compounds (I, VIIc, VIIe, VIIf, VIII, IX) elicited a remarkable activity against HCT116. Compounds showing significant anticancer activity revealed remarkable CDK9 inhibitory potential (IC₅₀ = 0.63–1.32 μM) relative to sorafenib (IC₅₀ = 0.76 μM). Moreover, a molecular docking study was performed to illustrate the binding mode of the most active compounds in the active site of CDK9 where it revealed superior binding affinity relative to the natural ligand (T3C).     

Effect of supersaturated aqueous hydrocortisone concentrations on the Δ1-dehydrogenase activity of free and immobilized Arthrobacter simplex

Supersaturated aqueous solutions of hydrocortisone have been prepared using hydrocortisone-poly(vinylpyrrolidone) (PVP) coprecipitates. Using these the hydrocortisone concentration in calcium alginate beads was increased severalfold. However, supersaturation reduced the Δ¹-dehydrogenase [3-oxosteroid:(acceptor) Δ¹-oxidoreductase, EC 1.3.99.4] activity of free and immobilized Arthrobacter simplex due to substrate inhibition. PVP coprecipitates may prove a useful tool for studying the effect of an increased soluble concentration of hydrophobic compounds in the absence of organic solvents.     

Isolation Purification and Characterization of Antimicrobial Peptides from <Emphasis Type="Italic">Cuminum cyminum</Emphasis> L. Seeds

In this work, antimicrobial peptides from Cuminum cyminum L. seeds were isolated and purified for the first time by 50% ethanol extraction, C18 reverse phase column chromatography and ion exchange chromatography for separation different peptides fraction. Then isolated fractions were characterized by Gel electrophoresis (SDS-PAGE), high-pressure liquid chromatography and the peptides components and molecular weights were determined by liquid chromatography and mass spectrometry. The extracts were tested against some strains of bacteria (E. coli and Staphylococcus aureus) and one strain of fungi (Candida albicans) using well diffusion and broth dilution assays. The extracts from C. cyminum L. seeds demonstrated a high degree of activity (some antibacterial effect) against the bacteria strains and аntifungal activity against the Candida albicans. However, the study indicates that the crude peptide extracts from C. cyminum L. seeds have promising antimicrobial and antioxidant activities that can be harnessed as leads for potential bioactive compounds.     

Catalytic activity of α-chymotrypsin in enzymatic peptide synthesis in ionic liquids

The catalytic activity of α-chymotrypsin in the enzymatic peptide synthesis of N-acetyl-l-tryptophan ethyl ester with glycyl glycinamide was examined in ionic liquids and organic solvents. The water content in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([emim][FSI]) affected the initial rates of peptide synthesis and hydrolysis. The activity of α-chymotrypsin was influenced by a kind of anions consisting of the same cation, [emim], when an ionic liquid was used as a solvent. The initial rate of peptide synthesis was improved 16-fold by changing from an organic solvent, acetonitrile, to an ionic liquid, [emim][FSI], at 25 °C. The activity of α-chymotrypsin in the peptide synthesis in [emim][FSI] was 17 times greater than that in acetonitrile at 60 °C, although the activity of α-chymotrypsin in the peptide synthesis gradually decreased with an increase in reaction temperature in [emim][FSI], similar to organic solvents. Moreover, α-chymotrypsin exhibited activity in [emim][FSI] and [emim][PF₆] at 80 °C.     

A novel actinomycete Streptomyces aurantiogriseus with algicidal activity against the toxic cyanobacterium Microcystis aeruginosa

A novel actinomycete strain (PK1) was isolated from soil in Khon Kaen Province, Thailand, and was capable of inhibiting the cyanobacterium Microcystis aeruginosa. The isolate PK1 was identified as Streptomyces aurantiogriseus based on an analysis of biochemical and morphological characteristics and 16S rDNA sequence. The algicidal activity of PK1 against M. aeruginosa depended on the growth phase of PK1, but not on the cyanobacterial growth phase. Stationary growth phase cultures of the strain PK1 exhibited the highest anti-Microcystis activity when co-cultivated with M. aeruginosa. Complete growth inhibition was observed after 8 days of co-cultivation in liquid culture medium. The algicidal compounds were extracted from PK1 with ethyl acetate and then purified by silica gel column chromatography. These partially purified compounds demonstrated algicidal activity against M. aeruginosa, suggesting that the strain PK1 provides a potential source of extracellular compounds for the control of M. aeruginosa bloom. This is the first report of anti-cyanobacterial activity from the soil actinomycete S. aurantiogriseus.     

Utilization of the label from bacterial [3H] DNA by isolated barley roots and embryos under different conditions

[³H] DNA fromEscherichia coli and [³H] thymidine were applied, in sterile conditions, on isolated barley embryos and on roots excised from these embryos, both cultivated in the liquid medium and on halves of barley seeds, through the endosperm bridge. In embryos and roots, the labelled compounds were applied in 1.5% sucrose + 0.2 SSC alone, or together with either unlabelled thymidine or DEAE-dextran. Similar labelling indices were found after [³H] thymidine and [³H] DNA treatment which shows that the activity of [³H] DNA is utilized during the S phase. After application of [³H] thymidine, only cell nuclei in S phase were labelled. After the application of [³H] DNA an extranuclear label, in addition to the labelling of nuclei in the S phase, was observed in some experimental variants. The density of label above labelled nuclei after [³H] DNA treatment sharply decreased when unlabelled thymidine or DEAE-dextran was added, while the density of label above nuclei labelled by [³H] thymidine decreased when unlabelled thymidine but not DEAE-dextran was added. The labelling of nuclei with the label from [³H] DNA is the result of degradation of exogenous DNA reutilization of low molecular weight products. Extranuclear labelling is most probably due to the polymerous or partly degraded DNA.     

Benzo[b]thiophene-6-carboxamide 1,1-dioxides: Inhibitors of human cancer cell growth at nanomolar concentrations

Benzo[b]thiophenesulfonamide 1,1-dioxide derivatives (BTS) were described as candidate antineoplastic drugs. In the hope of finding new compounds with improved antitumour activity and reduced toxicity, we have designed and synthesized a small series of benzo[b]thiophene-6-carboxamide 1,1-dioxide derivatives (BTC) structurally related with the best reported BTS. Growth inhibition of HTB-54, CCRF-CEM and HeLa tumour cells lines at nanomolar concentrations was exhibited by some of the BTC. Hydrophobic substituents on the carboxamide group increased cytotoxicity but substitution by a hydroxy group diminished it, thus pointing to the electronic density on benzo[b]thiophene nucleus as a determinant factor. The process of cell death induced by BTC derivatives was further analyzed in CCRF-CEM cells, where these compounds induced apoptosis in a time and dose-dependent manner and cell cycle arrest at S phase. BTC derivatives also induced a significant increase in intracellular ROS levels in this cell line. Previous treatment of the cells with the antioxidant N-acetyl-cysteine abrogated the induction of apoptosis by BTC indicating that ROS generation is a previous event required to trigger the BTC induced apoptotic process.     

Coprinus comatus Damages Nematode Cuticles Mechanically with Spiny Balls and Produces Potent Toxins To Immobilize Nematodes

We reported recently a unique fungal structure, called the spiny ball, on the vegetative hyphae of Coprinus comatus (O. F. Müll.:Fr.) Pers. Although some observations regarding the role of this structure were presented, its function remained largely unknown. In this study, we showed that purified (isolated and washed) spiny balls could immobilize and kill the free-living nematode Panagrellus redivivus Goodey highly efficiently. Scanning electron microscopy studies illustrated that the spiny structure damaged the nematode cuticle, suggesting the presence of a mechanical force during the process of nematode immobilization. Severe injuries on nematode cuticles caused the leakage of inner materials of the nematodes. When these structures were ground in liquid nitrogen, their killing efficacy against nematodes was lost, indicating that the shape and the complete structure of the spiny balls are indispensable for their function. However, extraction with organic solvents never lowered their activity against P. redivivus, and the extracts showed no obvious effect on the nematode. We also investigated whether C. comatus was able to produce toxins which would aid in the immobilization of nematodes. In total, we identified seven toxins from C. comatus that showed activity to immobilize the nematodes P. redivivus and Meloidogyne incognita (Kofoid et White) Chitwood. The chemical structures of these toxins were identified with nuclear magnetic resonance, mass spectrometry, infrared, and UV spectrum analysis. Two compounds were found to be novel. The toxins found in C. comatus are O-containing heterocyclic compounds.     

Crystal structure,antitumour and antimetastatic activities of disubstituted fused 1,2,4-triazinones

Molecular structure of 3,8-disubstituted 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones (8–14) was confirmed by X-ray crystallography of 14. All the compounds were evaluated for their antitumour and antimetastatic activities in vitro. Furthermore, their cytotoxicities towards human normal cell line—HSF cells were established, allowing us to point out some structure–activity relationships. Among them, imidazotriazinone 12, revealing remarkable dose-dependent viability decreases in human myeloma RPMI 8226 cells, was found to be completely non-toxic towards normal HSF cells. In addition, heterobicycles 8–12 were proved to exhibit significant antimetastatic potentials in the motility assay.     

N2-Trimethylacetyl substituted and unsubstituted-N4-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines: Design,cellular receptor tyrosine kinase inhibitory activities and in vivo evaluation as antiangiogenic,antimetastatic and antitumor agents

Six novel N⁴-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines and their N²-trimethylacetyl substituted analogs were synthesized as receptor tyrosine kinase (RTK) inhibitors. A microwave-mediated Sonogashira reaction was used as a key step for the synthesis of these compounds. Biological evaluation, in whole cell assays, showed that some analogs had remarkable inhibitory activity against a variety of RTKs and in particular cytotoxic activity against A431 tumor cells in culture. The inhibitory data against RTKs in this study demonstrated that variation of the 4-anilino substituents of these analogs dictates both potency and specificity of inhibitory activity against various RTKs. The study also supported the hypothesis that interaction of substituents on the 2-amino group with hydrophobic site-II provides an increase in potency. Compound 8 of this series was selected for evaluation in vivo in a B16-F10 syngeneic mouse tumor model and exhibited significant reduction in tumor growth rate, in tumor vascular density and in metastases to the lung compared to the control.     

Antifungal Activity of Isothiocyanates and Related Compounds: I. Naturally Occurring Isothiocyanates and Their Analogues

Data are presented concerning the antifungal activity of 11 natural isothiocyanates and 27 synthetized analogues in Aspergillus niger, Penicillium cyclopium, and Rhizopus oryzae, as well as in 13 additional saprophytic and parasitic fungi. A remarkable antifungal activity was observed in some analogues of benzylisothiocyanate and β-phenylethylisothiocyanate. The latter-mentioned compounds have not been described previously. In the group of benzylisothiocyanates, a correlation, which was inversely proportional, was detected between ed₁₀₀ values for A. niger and R. oryzae and the corresponding molar solubilities of compounds in water. In contradistinction, no relationship was observed between antifungal activity and chemical reactivity of investigated derivatives.     

Synthesis of cembranoid analogues and evaluation of their potential as quorum sensing inhibitors

Natural cembranoids have shown Quorum Sensing Inhibitory (QSI) activity, but their structure–function interactions are not well understood. Thirty-four cembranoid analogues were synthesized using six natural cembranoids (1–6) previously isolated from the Colombian Caribbean octocorals Eunicea knighti and Pseudoplexaura flagellosa as lead compounds. The analogues (7–40) obtained through the selected chemical transformations were tested in vitro against the QS systems of a Chromobacterium violaceum biosensor. Half of the cembranoid analogues assayed showed superior QSI activity to the lead compounds; three (8, 13, and 18) displayed remarkable potency up to three times higher than the natural compounds. Thereby, we have synthesized a pool of cembranoid QS inhibitors that can be used in concert with natural compounds to develop antipathogenic drugs and antifouling agents.     

Efficient synthesis of antifungal active 9-substituted-3-aryl-5H,13aH-quinolino[3,2-f][1,2,4]triazolo[4,3-b][1,2,4]triazepines in ionic liquids

The title compounds, 9-substituted-3-aryl-5H,13aH-quinolino[3,2-f][1,2,4]triazolo[4,3-b][1,2,4]triazepines 8, are synthesized from 5-aryl-3,4-diamino-1,2,4-triazoles 5 and 2-chloro-3-formylquinolines 7 in ionic liquid as solvent under microwave heating as well as using oil-bath heating at 80 °C. The products are obtained in the good to moderate yields and in high purity. These compounds have been screened for antifungal activity. The screening data indicate that the compounds 8a, 8b, 8c and 8d show excellent activity against Aspergillus niger 1000 μg concentration and Pencillium notatum species at 500 μg as well as 1000 μg concentrations whereas, these compounds show good to moderate activity against Aspergillus flavus and Rhizopus species at both the concentrations. Moreover, ionic liquid is found to be recyclable for at least three consecutive runs what makes the process cost-effective and economic that lead to the area of Green Chemistry as recyclability is one of the most important feature of Green Chemistry.     

Synthesis and antibacterial activity of some new benzo[5,6]chromeno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

The synthesis and antibacterial activity of some new benzo[5,6]chromeno[2,3-d]pyrimidine derivatives are described. The title compounds were obtained by the reaction of 1H-benzo[f]chromenes with aliphatic and aromatic amines. The structures of all newly synthesized compounds were confirmed by IR, ¹HNMR, ¹³C NMR, and NOESY experiments. The compounds exhibited potent antibacterial activity against gram-positive and gram-negative bacterial species. 10-Methyl-12-(4-hydroxyphenyl)-10,12-dihydro-11H-benzo[5,6]chromeno[2,3-d] pyrimidin-11-imine displayed greater antibacterial activity against gramnegative bacterial species than did ciprofloxacinandamoxicillin.     

Potential of Candida utilis to ferment Ecklonia cava by-product for enhanced anti-methicillin-resistant Staphylococcus aureus (MRSA) activity

In order to utilize the by-product of Ecklonia cava (the remaining biomass of E. cava), microbial fermentation which may result in the production of bioactive compounds using the by-product was applied in this study. The fermentation broth of E. cava by-product fermented with Candida utilis showed enhanced antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and food-borne pathogenic bacteria compared to that of control. To perform a more detailed investigation on the antibacterial activity, the broth was extracted with methanol and further fractionated with organic solvents. After 1 day of fermentation, the ethyl acetate (EtOAc) fraction exhibited the highest anti-MRSA activity with minimum inhibitory concentration ranging from 64 to 256 μg mL^?1, suggesting that the fermentation of E. cava by-product with C. utilis could enhance antibacterial activity against MRSA. In addition, high-performance liquid chromatography analysis revealed that dieckol, eckol, eckstolonol, and triphlorethol-A contents in the EtOAc-soluble extract increased significantly. The anti-MRSA activity of E. cava by-product most probably originated from phlorotannins, and the fermentation of C. utilis may have stimulated the breakdown of phlorotannins or have increased the efficiency in extracting phlorotannins.     

Synthesis and evaluation of novel 2,3,5-triaryl-4H,2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-diones for advanced glycation end product formation inhibitory activity

The synthesis of some biologically interesting pyrrolo-isoxazolidine derivatives was accomplished by the 1,3-dipolar cycloaddition reaction of substituted azomethine N-oxides 1 with substituted N-aryl maleimides 2 leading to the formation of new stereoisomeric 2,3,5-triaryl-4H,2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione derivatives 3 in excellent yields. The synthesized compounds have been screened for their advanced glycation end (AGE) product formation inhibitory activity on the basis of their ability to inhibit the formation of AGEs in the bovine serum albumin (BSA)-glucose assay. All the synthesized compounds have been found to exhibit significant activity against AGE formation.