Molar conductance,magnetic susceptibility,mass spectra,and thermal decomposition studies on Cu(II) compounds with substituted terpyridines and clioquinol drug

Octahedral copper(II) complexes with substituted terpyridines and clioquinol drug have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility, thermal decomposition, infrared spectra, ¹H-NMR spectra, and FAB mass spectroscopy. The antibacterial activities of the newly synthesized compounds were evaluated and correlated with their physicochemical properties. Results revealed that the tested compounds exhibited better inhibitory activities than the reference antibacterial quinolone drugs against Gram(+ve) and Gram(?ve) bacteria.     

Synthesis,Structural Reassignment,and Antibacterial Evaluation of 2,18‐Seco‐Lankacidinol B

Lankacidins are a group of polyketide natural products with activity against several strains of Gram‐positive bacteria. We developed a route to stereochemically diverse variants of 2,18‐seco‐lankacidinol B and found that the stereochemical assignment at C4 requires revision. This has interesting implications for the biosynthesis of natural products of the lankacidin class, all of which possessed uniform stereochemistry prior to this finding. We have evaluated 2,18‐seco‐lankacidinol B and three stereochemical derivatives against a panel of pathogenic Gram‐positive and Gram‐negative bacteria.     

Synthesis,Structural Reassignment,and Antibacterial Evaluation of 2,18‐Seco‐Lankacidinol B

Lankacidins are a group of polyketide natural products with activity against several strains of Gram‐positive bacteria. We developed a route to stereochemically diverse variants of 2,18‐seco‐lankacidinol B and found that the stereochemical assignment at C4 requires revision. This has interesting implications for the biosynthesis of natural products of the lankacidin class, all of which possessed uniform stereochemistry prior to this finding. We have evaluated 2,18‐seco‐lankacidinol B and three stereochemical derivatives against a panel of pathogenic Gram‐positive and Gram‐negative bacteria.     

Synthesis and antibacterial activity of a new series of 2,3,5,7-substituted-pyrido[2,3-d]pyrimidin-4(3h)-one derivatives

A new series of 2,3,5,7-substituted-pyrido[2,3-d]pyrimidin-4(3H)-one derivatives were prepared from 2-amino-N,6-substituted phenyl-4-(trifluoromethyl or methyl)nicotinamides. The key intermediate 2-amino-N,6-substituted phenyl-4-(trifluoromethyl or methyl)nicotinamides were synthesized from 2-bromo-N,6-disubstituted phenyl-4-(trifluoromethyl or methyl)nicotinamides as well as from ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) coupling of 2-amino-4,6-substituted nicotinic acid and substituted arylamines. All the synthesized compounds were screened for antibacterial activity against Gram +ve and Gram -ve bacteria. Compound 7c showed better antibacterial activity against Gram +ve and Gram -ve bacteria.     

Synthesis,Characterization, and Evaluation of Antibacterial and Antioxidant Activities of Novel Benzoxazinones and Benzoxathiinones

In this work, the new benzoxazinones and benzoxathiinones were synthesized from reaction of alkyl X‐phenylpropiolates and aminophenol (or 2‐mercaptophenol) in the presence of triphenylphosphine. Their antibacterial activities were studied against Gram‐positive bacteria and Gram‐negative bacteria using the disc diffusion method. The obtained results showed that these compounds are more effective against Gram‐positive bacteria than against Gram‐negative bacteria. Also, evaluation of antioxidant activity of the obtained products showed that they have high to excellent antioxidant activity (79.2–93.6%).     

Three-component synthesis and antibacterial evaluation of some novel 1,2-dihydroisoquinoline derivatives

Isoquinoline reacts with dialkyl acetylenedicarboxylates in the presence of kojic acid or8-hydroxyquinoline to generate 1,2-dihydroisoquinoline derivatives. The simplicity, mild reaction conditions and high yields of products make it an interesting process compared to other approaches. The compounds have been analyzed for antibacterial activity against Gram negative and Gram positive bacteria. The results indicated that 1,2-dihydroisoquinolines derived from kojic acid are effective against all of the studied bacteria especially against Bacillus subtilis, while the products obtained from8-hydroxyquinoline are active only against Gram positive bacteria.     

Synthesis,spectral and antimicrobial studies of rare earth metal complexes with Schiff-base hydrazone containing quinoline moiety

The synthesis and characterization of lanthanide(III) complexes with the Schiff-base hydrazone, o-hydroxyacetophenone-7-chloro-4-quinoline, (HL) are reported. The complexes were characterized by different physicochemical methods: mass spectrometry, ¹H NMR, ¹³C NMR, and IR, UV-visible, molar conductance and magnetic studies. They have the stoichiometry [Ln(L)₂(NO₃)]·nH₂O where Ln = La(III), Pr(III), Nd(II), Sm(III), Eu(III) and n = 1–3. The spectra of the complexes were interpreted by comparison with the spectrum of the free ligand. The Schiff-base ligand and its metal complexes were tested against one stain Gram +ve bacteria (Staphylococcus aureus), Gram ?ve bacteria (Escherichia coli), and Fungi (Candida albicans). The tested compounds exhibited high antimicrobial activities     

Synthesis, characterization and antimicrobial activity of 3d transition metal complexes of a biambidentate ligand containing quinoxaline moiety

A new series of oxovanadium(IV), chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), and copper(II) complexes of the 3-hydrazino quinoxaline-2-one (HQO) were prepared and characterized. The ligand exhibits biambidenticity. It behaves as a bidentate ON donor in oxovanadium(IV), iron(III) and copper(II) complexes and as a bis bidentate ONNN donor in chromium(III), manganese(II), cobalt(II) and nickel(II) complexes. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, thermal, infrared, ¹H NMR, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes. All the complexes show subnormal magnetic moments. The ligand, HQO, and its complexes were tested against one strain Gram +ve bacteria (Staphylococcus aureus), Gram −ve bacteria (Escherichia coli). The prepared metal complexes exhibited higher antimicrobial activities than the parent ligand.     

Synthesis of 3-benzoyl-4-benzylfurans structural related to furolignans

Abstract

Furolignan-type natural products, possessing important biological properties, have been synthesized from a commercially available furan. The elaborated synthetic strategy is based on an innovative Friedel-Crafts reaction starting from an alcohol or a carboxylic acid and triflic anhydride as promoter. Through this synthetic strategy, furolignans having two different aryl groups have been obtained. The products have been evaluated for their antimicrobial properties on Gram positive and Gram negative bacteria, in order to compare their biological activities with those of natural analogues.     

Convenient Synthesis and Biological Activity of Mono and Diacyl 2,5‐Dimercapto‐1,3,4‐thiadiazole Derivatives

New derivatives of 2,5‐dimercapto‐1,3,4‐thiadiazole substituted both at one or two exocyclic sulfur atoms with a series of aroyl or ethoxycarbonyl groups were synthesized in reactions of 2,5‐dimercapto‐1,3,4‐thiadiazole salts with appropriate acid chlorides or ethyl chloroformate in mild conditions. The products were characterized by spectroscopy (¹H NMR, ¹³C NMR, IR, and HRMS). Some from the synthesized compounds were screened in vitro and in vivo for antibacterial and antifungal activities against a panel of reference strains of microorganisms. The study revealed that ethyl S‐(5‐mercapto‐1,3,4‐thiadiazol‐2‐yl) carbonothioate seems to be the most active and versatile compound against Gram‐positive bacteria, Gram‐negative bacteria, and plant pathogenic fungi.     

In situ Synthesis of Oil Based Polymer Composites Containing Silver Nanoparticles

Using electron transfer reaction and free radical polymerization processes a series of triglyceride oil based polymer‐silver nanocomposites were successfully prepared. The whole process was divided into two simultaneous stages; (i) copolymerization of macromonomers obtained from partial glycerides with styrene and (ii) the reduction of silver nitrate to metallic silver nano particles with radicals stemming from the thermolysis of 2,2′‐azoisobutyronitrile (AIBN). Nanocomposites were characterized by TEM and TGA. The obtained polymer nanocomposite was also examined in view of antibacterial effect against Gram‐positive, Gram‐negative, and Spore forming bacteria. It was demonstrated that nanocomposite samples exhibited an antibacterial effect against these bacteria. Film properties of the samples as potential coating material were also studied. Nanocomposite samples showed better film properties than that of the polymer without silver nanoparticles.     

Silica‐gel‐supported Phosphorus Pentoxide:a Simple and Efficient Solid‐supported Reagent for Esterification of Long‐ Chain Carboxylic Acids and Their Antimicrobial Screening

A silica-gel-supported heterogeneous phosphorus pentoxide reagent has been developed for the esterification of various long-chain carboxylic acids with aromatic alcohols. The reactions occurred under relatively mild conditions and afforded the desired products in good yields. All the compounds 3a—3x were screened for antibacterial and antifungal activity, which showed good activity against Gram positive and Gram negative bacteria and also good results against almost all fungal strains. The structures of the synthesized compounds were elucidated by IR, ¹H NMR, ¹³C NMR, mass spectroscopic techniques and elemental analysis.     

Efficient Synthesis of New Pyrimido[5′,4′:5,6]pyrano[2,3-d]pyrimidine-2,4,6(1H,3H)-triones via the Tandem Intramolecular Pinner–Dimroth Rearrangement,and Their Antibacterial Activity

Synthesis of new 8-alkyl-5-aryl-1,3-dimethyl-5,7-dihydro-2H-pyrimido[5′,4′:5,6]pyrano[2,3-d]- pyrimidine-2,4,6(1H,3H)-triones by the high yield reaction of 7-amino-5-aryl-1,3-dimethyl-2,4-dioxo-1,3,4,5- tetrahydro-2H-pyrano[2,3-d]pyrimidine-6-carbonitriles with aliphatic carboxylic acids in the presence of POCl3 is presented. It is probable that synthesis of these new products proceeds via the tandem intramolecular Pinner–Dimroth rearrangement. The products are characterized by FT-IR, ¹H, and ¹³C NMR spectra and evaluated for their antibacterial activity against gram +ve bacteria (Staphylococcus aureus and Staphylococcus epidermidis) and gram–ve bacteria (Escherichia coli and Pseudomonas aeruginosa) using the disc diffusion method.

     

Synthesis of novel triazolothione,thiadiazole, triazole-functionalized furo/thieno[2,3-b]pyridine derivatives and their antimicrobial activity

A series of novel triazolothione, thiadiazole, triazole-functionalized furo/thieno[2,3-b]pyridine derivatives 9a–l, respectively, were prepared starting from 2 (1H) pyridone 3 through selective O/S-alkylation followed by Thorpe–Ziegler cyclization to form furo/thieno[2,3-b]pyridine derivatives 6. Compounds 6 on reaction with hydrazine hydrate resulted carbohydrazide derivatives 7 and further reacted with diverse substituted phenyl isothiocyanates to form phenyl hydrazine carbothiamide derivatives 8. Each compound 8 is independently reacted in presence of NaOH, H₂SO₄, and N₂H₄.H₂O to form triazolothione, thiadiazole, triazole-functionalized furo/thieno[2,3-b]pyridine derivatives 9a–l, respectively. All the products 9a–l were screened against Gram +ve, Gram –ve bacteria and fungal strains. Compounds 9c–h showed high activity against Bacillus subtilis microbial-type culture collection (MTCC) 121 at <8.0 micromolar concentration. Promising compounds further screened for minimum bactericidal concentration against B. subtilis MTCC 121 using ciprofloxacin as standard and found to show very good activity. These compounds also screened for biofilm inhibition activity against B. subtilis MTCC 121 using erythromycin as standard and confirmed the high activity.     

Synthesis and antimicrobial activity of some 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones

The title compounds, 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been synthesized by reacting various 4‐hydroxy coumarins 1a , 1b , 1c with 2‐arylidene‐1‐tetralones 2a , 2b , 2c , 2d in the presence of ammonium acetate and acetic acid under Krohnke's reaction condition. The structures of all the synthesized compounds were supported by analytical, IR, ¹H‐NMR, and ¹³C‐NMR data. All the synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been screened for their antibacterial activities against Escherichia coli (Gram ?ve bacteria), Bacillus subtilis (Gram +ve bacteria), and antifungal activity against Candida albicans (Fungi). J. Heterocyclic Chem., (2011).     

Theoretical,antimicrobial, antioxidant,in vitro cytotoxicity,and cyclin-dependent kinase 2 inhibitor studies of metal(II) complexes with bis(imidazol-1-yl)methane-based heteroscorpionate ligands

Abstract

A series of C-centered heteroscorpionate-based homoleptic manganese(II), nickel(II), and copper(II) complexes of type [M(L^1–3)₂] (1–9) have been synthesized by using the ligands (2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL¹), (4-diethylamino-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL²) and (5-bromo-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL³). The geometric parameters of the complexes were determined using UV-vis and theoretical studies suggesting distorted octahedral geometry around metal(II) ion. Frontier molecular orbital analysis supports bioefficacy of the complexes. Antimicrobial activity of the metal(II) complexes were determined against two Gram(–ve) (Escherichia coli and Klebsiella pneumoniae) and two Gram(+ve) (Bacillus cereus and Staphylococcus aureus) bacteria, and three fungal (Candida albicans, Candida glabrata, and Candida krusei) strains. Antioxidant activity of nickel(II) and copper(II) complexes were evaluated against ABTS, DPPH, and H₂O₂ free radicals. In vitro cytotoxicity activity of nickel(II) and copper(II) complexes against human breast adenocarcinoma (MCF-7), cervical (HeLa), and lung (A549) cancer cell lines along with one normal human dermal fibroblasts (NHDF) cell line were carried out by MTT assay, which shows the potent activity of copper(II) complex 8 with respect to the standard drug cisplatin. Molecular docking studies evidence the interaction of complexes with cyclin-dependent kinase 2 receptor (CDK2).     

Synthesis of novel macrocyclic Schiff's‐base and its complexes having N2O2 group of donor atoms. Characterization and anticancer screening are studied

Novel Schiff base [N ′,N ′″‐(((ethane‐1,2‐diylbis(oxy))bis(2,1‐phenylene))bis(methanylylidene))di(benzohydrazide)] was formed by the condensation reaction of benzohydrazide with 2,2′‐(ethane‐1,2‐diylbis(oxy))dibenzaldehyde. Its reaction with various metal ions was studied and the structures of the new products were characterized using common analytical and spectroscopic methods. All the metal complexes have pronounced anticancer activities. The antimicrobial activities against Gram‐negative and Gram‐positive bacteria were investigated.     

O‐Glycosylation/Alkylation and Antimicrobial Activity of 4,6‐Diaryl‐2‐Oxonicotinonitrile Derivatives

A series of glycosylation and alkylation reactions of 6‐phenanthernyl‐2‐pyridone derivatives 1a , 1b containing electron withdrawing and electron donating substituents at 4‐position is reported. Regioselective 2‐O‐ alkylated/glycosylated products were obtained exclusively, irrespective of the electronic nature of alkylating or the glycosyling agent. Glycosylation of 1a , 1b with glucosyl/galactosyl and lactosyl bromides afforded 2a , 2b ; 4a , 4b ; and 6a , respectively. Alkylation of 1a , 1b with epichlorohydrin, propargyl, allyl bromides, and 3‐chloropropanol resulted in compounds 8 , 9 , 10 and 13 , respectively. Deprotection of O‐glycosylated products under conventional conditions provided the free glycosides 3a , 3b ; 5a , 5b ; 7a , 12 ; and 13 , respectively. The minimal inhibitory concentration for some of the newly synthesized compounds showed high significant activity against Gram (+ve) and Gram (−ve) and antifungal activities. Among the screened compounds, the 4‐trifluromethyl phenyl derivatives 2a , 3a , 4a , 8a , and 11a exhibited strong antimicrobial activity.     

Synthesis and Antimicrobial Activity of Novel Azolopyrimidines and Pyrido‐Triazolo‐Pyrimidinones Incorporating Pyrazole Moiety

A new series of azolopyrimidine derivatives incorporating pyrazole moiety were synthesized by reaction of 1‐(pyrazol‐3‐yl)‐2‐propenone with a number of heterocyclic amines in the presence of a catalytic amount of acetic acid. The mechanism of formation of the products was also discussed, and the structure assigned was elucidated based on both elemental and spectral analyses data. In addition, 7‐(pyrazolyl)‐2‐thioxo‐5‐phenyl‐1,3‐dihydropyrido[2,3‐d ]pyrimidin‐4‐one was used as starting material for preparation of a new series of pyridotriazolopyrimidines via its reaction with a variety of hydrazonoyl chlorides in dioxane using triethylamines as catalyst. The assigned structure for these products was also proved via elemental analysis and spectroscopic techniques (IR, ¹H NMR, and Mass). Moreover, the antimicrobial activity of some selected examples of the new products was evaluated, and the results obtained revealed high activity of compound 20a against the Gram positive bacteria Staphylococcus aureus and the Gram negative bacteria Klebsiella pneumonie . All the tested compounds have no antifungal activity.     

Synthesis and antimicrobial evaluation of some new bicyclopyrazolone‐based thiopyran ring systems

A series of bicyclopyrazolones were synthesized from the condensation reaction of methyl 4‐oxotetrahydro‐2H‐thiopyran‐3‐carboxylate with hydrazine derivatives in ethanol. All synthesized products were characterized by FT‐IR, ¹H, and ¹³C NMR spectral data, elemental analyses, and mass spectrometry. The antibacterial and antifungal activities of these compounds were evaluated against Staphylococcus aureus and Bacillus subtilis as Gram‐positive bacteria, Escherichia coli and Pseudomonas aeruginosa as Gram‐negative bacteria, and the fungus Candida albicans. The results revealed that bicyclopyrazolones including an aryl or aryl sulfonyl group in the N‐2 position of the pyrazolone moiety are the most effective against all the microorganisms studied in this work.