Synthesis and Antimicrobial Studies of Organophosphates Derived From 2-(2″-Hydroxynaphthyl)Benzoxazole

Abstract

A series of biologically active phenoxy derivatives of 2-substituted benzoxazole organophosphates have been synthesized by the reaction of O-(naphthyl benzoxazolyl-2-) phosphorodichloridate/phosphorodichloridothioate with phenol/4-chlorophenol/4-nitroph- enol in 1:1 and 1:2 molar ratios. These compounds have been characterized on the basis of elemental analysis, IR, ¹H NMR, ³¹P NMR, and mass spectral studies. The antibacterial activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (?ve). The antifungal activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. All compounds were found to have significant antibacterial and antifungal activity.     

Microwave assisted synthesis of 4-methyl-3-arylpyrano[2,3-f]chromen-2(8H)-one derivatives,evaluation of antiproliferative,and antimicrobial activities

A series of new 4-methyl-3-arylpyrano[2,3-f]chromen-2(8H)-one derivatives were designed and synthesized through an efficient, an eco-friendly manner under microwave irradiation and conventional heating methods. Structures of final compounds established based on IR, NMR and mass spectral analysis. The final target compounds were screened for their in vitro antiproliferative activity by taking cisplatin as a reference, Further, antibacterial activity by taking strains such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia and Escherichia coli. Furthermore, antifungal activity screened with Aspergillus niger, Aspergillus flavus and Fusarium oxysporum strains. Many compounds results good activity.     

Synthesis of novel thiazol-5-ylpyrimidine derivatives and their antimicrobial evaluation

Novel thiazol-5-ylpyrimidine derivatives were designed and synthesized. The chemical structures of all new synthesized compounds were assigned by studying their elemental analyses and spectral data (FT-IR, ¹HNMR, ¹³C NMR, and MS). The target compounds, 8 and 9a-9d were evaluated for their antimicrobial activity in vitro against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, gram-negative bacteria, Salmonella abony and Escherichia coli and fungi, Aspergillus flavus and Fusarium oxysporum. In particular, compounds 9a-9c exhibited moderate to good activity against gram-positive bacteria, S. aureus, gram-negative bacteria, S. abony and fungus, Fusarium oxysporum in comparison with reference drugs.     

Synthesis,characterization and in vitro cytotoxicity of palladium(II) complexes with mixed ligands. X‐ray diffraction study of C31H36ClNPPdS2

Pd(II) complexes with organophosphines and dithiocarbamates derivatives of α‐amino acids were synthesized by reacting N,N‐dicyclohexyldithiocarbamate (DCHDTC, compounds 1 – 3 ) and N‐methylcyclohexyldithiocarbamate (MCHDTC, compounds 4 – 6 ) with (R₃P)₂PdCl₂ (R = Ph, o‐tolyl, Ph₂Cl) in a 1:1 molar ratio. The complexes were characterized by elemental analyses, FT‐IR, multinuclear (¹H, ¹³C and ³¹P) NMR and single X‐ray crystallography, showing that the dithiocarbamate acts as a bidentate ligand and binds to Pd(II) via two sulfur atoms, resulting in a square planar geometry around Pd(II). The cytotoxicity of compounds 2, 3 and 4 was determined in vitro against six human tumour cell lines, MCF7, EVSA‐T, WIDR, IGROV, M19 MEL, A498 and H226. Compounds 3 and 4 showed a moderate to low cytotoxicity, whereas compound 2 exhibited a very low cytotoxicity. The results of antifungal assays showed that compounds 1 – 6 possess antifungal activity against Fusarium moniliformes, Fusarium saolani, Mucor sp., Aspergillus niger and Aspergillus fumigatus. The anti‐inflammatory screening results of 1–6 are quite similar to those observed for the standard drug Declofenac at 10 mg kg^?1, which inhibited the odema by 74% after 4 h. Copyright © 2007 John Wiley & Sons, Ltd.     

Investigation of fungicidal activity of 3‐piperazine‐bis(benzoxaborole) and its boronic acid analogue

3‐Piperazine‐bis(benzoxaborole) and its bis(phenylboronic acid) analogue were investigated in terms of their fungicidal activity. The study was carried out against five filamentous fungi: Aspergillus terreus, Fusarium dimerum, Fusarium solani, Penicillium ochrochloron and Aspergillus niger. 3‐Piperazine‐bis(benzoxaborole) revealed higher inhibitory activity towards the examined strains than standard antibiotic (amphotericin B), whereas bis(phenylboronic acid) proved to be inactive. The study unequivocally showed that the presence of the heterocyclic benzoxaborole system is essential for antifungal action of the examined compounds. Copyright © 2014 John Wiley & Sons, Ltd.     

Pharmacophore generation,atom-based 3D-QSAR,HQSAR and activity cliff analyses of benzothiazine and deazaxanthine derivatives as dual A2A antagonists/MAO‑B inhibitors

Dual inhibition of A_2A and MAO-B is an emerging strategy in neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). In this study, atom-based three-dimensional quantitative structure–activity relationship (3D-QSAR) and hologram quantitative structure–activity relationship (HQSAR) models were generated with benzothiazine and deazaxanthine derivatives. Based on activity against A_2A and MAO-B, two statistically signi?cant 3D-QSAR models (r² = 0.96, q² = 0.76 and r² = 0.91, q² = 0.63) and HQSAR models (r² = 0.93, q² = 0.68 and r² = 0.97, q² = 0.58) were developed. In an activity cliff analysis, structural outliers were identified by calculating the Mahalanobis distance for a pair of compounds with A_2A and MAO-B inhibitory activities. The generated 3D-QSAR and HQSAR models, activity cliff analysis, molecular docking and dynamic studies for dual target protein inhibitors provide key structural scaffolds that serve as building blocks in designing drug-like molecules for neurodegenerative diseases.     

Regioselective synthesis and antimicrobial evaluation of some thioether–amide linked 1,4-disubstituted 1,2,3-triazoles

A series of 1,4-disubstituted 1,2,3-triazoles having thioether as well as amide linkage were synthesized from aryl(prop-2-yn-1-yl)sulfanes and 2-azido-N-substituted acetamides through Cu(I) catalyzed click reaction. Structures of newly synthesized compounds (3a–3x) were confirmed by spectral techniques like FTIR, ¹H NMR, ¹³C NMR, and HRMS. The synthesized triazoles were evaluated for in vitro antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Candida albicans, and Aspergillus niger. Compounds 3m and 3q displayed appreciable broad spectrum antimicrobial activity against tested microbial strains. The nanoformulations of compounds 3m and 3q were also prepared and examined against one bacterial strain and one fungal strain.     

Synthesis and Antimicrobial Activity of 1‐[(Substituted Carbamoyl)Amino]‐1H,3H‐1λ5‐[1,3,2]oxazaphospholo[3,4‐a]benzimidazol‐1‐ones

1‐[(Substituted carbamoyl)amino]‐1H,3H‐1λ⁵‐[1,3,2]oxazaphospholo[3,4‐a]benzimidazol‐1‐ones were synthesized by reacting benzimidazole 2‐methanol (4) with different chlorides of carbamidophosphoric acids (3) in the presence of triethylamine at 40–45°C. Their ¹H, ¹³C, and ³¹P NMR spectral data were discussed. The title compounds were tested for their activity against the fungi Aspergillus niger and Fusarium solani and bacteria Staphylococcus aureus and Escherichia coli. These compounds showed moderate antibacterial activity when compared with antifungal activity.     

Synthesis of biologically active phenoxy derivatives of substituted benzothiazole organophosphates

The reaction of S‐(phenyl benzothiazolyl‐2)phosphorodichloridothioate/phosphorodichloridodithioate with 2 mol of phenol/4‐chlorophenol/4‐nitrophenol in the presence of stoichiometric amounts of triethylamine in dry THF/CH₂Cl₂ has afforded a series of the corresponding organophosphate phenoxy derivatives ( 1a , 1b , 2a , 2b , and 3a , 3b ). Plausible structures have been proposed on the basis of elemental analysis, IR, ¹H NMR, ³¹P NMR, and mass spectral studies. The antibacterial activity of these organophosphate phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (−ve). The antifungal activity of these organophosphate phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. The results indicate that organophosphate phenoxy derivatives are found more active than the parent compounds. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:84–88, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20582     

Synthesis of New Triazole and Oxadiazole Derivatives of Quinazolin‐4(3H)‐one and Their Antimicrobial Activity

A series of new triazole derivatives of quinazolin‐4(3H)‐one and new oxadiazole derivatives of quinazolin‐4(3H)‐one were synthesized. The newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral data. All the newly synthesized compounds were screened for antibacterial activity against Staphylococcus aureus, Bacillus subtilis (gram‐positive bacteria), Escherichia coli, Pseudomonas aeruginosa (gram‐negative bacteria), and antifungal activity was carried out against Candida albicans and Aspergillus niger.     

Antimicrobial and Antimalarial Activity of Novel Synthetic Mononuclear Ruthenium(II) Compounds

The present work was aimed that the two Ruthenium compounds namely, [Ru(A)₂(B)]Cl₂, where A = 1,10‐phenanthroline; B = 2‐NO₂‐phenyl thiosemicarbazone (Compound R₁)/2‐OH‐phenyl thiosemicarbazone (Compound R₂) have been tested for antibacterial activity at the concentrations of 1 mg/mL against various Gram‐Positive organisms (Lactobacillus, Staphylococcus pyrogenes, Bacillus subtilis, Staphylococcus aureus & Bacillus megatarium) and Gram‐Negative organisms (Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Enterobacter aerogenes, Salmonella paratyphi, Klebsiella pneumonia & Proteus mirabilis). The compounds were also tested for antifungal activity against Aspergillus clavatus, Aspergillus niger, Colletotrichum & Penicillium notatum by using agar diffusion assay and antimalarial activity against Plasmodium falciparum (Strain 3D7) using MTT assay. The results concluded that the compound R₁ exhibited significant antibacterial activity than R₂ against Gram‐Negative bacteria with zones of inhibition ranging from 15‐20 mm. and mild antibacterial activity against Gram‐Positive bacteria in comparison to tetracycline, streptomycin and rifampicin. These complexes were found to have moderate antifungal activity with no activity was however observed against Aspergillus niger. The compound, R₁ exhibited antimalarial activity at 10 μg/mL, whereas R₂ did not show antimalarial activity upto 50 μg/mL. Sensitivity to the compounds was greatest in the gram‐negative bacteria, followed by the gram‐positive bacteria and fungi.     

Ultrasound‐assisted Synthesis of Novel Pyrazole and Pyrimidine Derivatives as Antimicrobial Agents

Herein, we report a convenient and facile methodology for the synthesis of new series of pyrazole and pyrimidine derivatives 2a – f and 3a – f under ultrasound irradiation. Pyrazole and pyrimidine derivatives have been synthesized in better yields and shorter reaction times compared with the conventional method. The chemical structures of all the synthesized compounds were elucidated by their IR, ¹H NMR, ¹³C NMR, MS, and elemental analysis. Further, the target compounds were screened for their antimicrobial activity against four bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa) and two fungi (Candida albicans, Aspergillus niger). In particular, compounds 2a , 2d , 2e , 3a , 3e , and 3f exhibited potent antimicrobial activity.     

One-pot facile synthesis,crystal structure and antifungal activity of 1,2,3-triazoles bridged with amine-amide functionalities

A library of twenty five 1,2,3-triazoles bridged with amine-amide functionalities have been synthesized from reaction of N-substituted(prop-2-yn-1-yl)amines (2a–2e), 2-bromo-N-arylacetamides (4a–4e) and sodium azide through copper(I)-catalyzed alkyne-azide cycloaddition. The synthesized compounds were characterized by using FTIR, ¹H NMR, ¹³C NMR, and HRMS techniques. The structures of synthesized 5a (CCDC 1569245) and 5h (CCDC 1569249) were also confirmed by X-ray crystallography. Antifungal evaluation of newly synthesized triazoles was carried out against – Candida albicans and Aspergillus niger. Biological screening of synthesized 1,2,3-triazoles revealed moderate to good antifungal activity against tested strains.     

Microbial carbonylation and hydroxylation of 20(R)-panaxadiol by Aspergillus niger

20(R)-panaxadiol (PD) was metabolised by the fungus Aspergillus niger AS 3.3926 to its C-3 carbonylated metabolite and five other hydroxylated metabolites (1–6). Their structures were elucidated as 3-oxo-20(R)-panaxadiol (1), 3-oxo-7β-hydroxyl- 20(R)-panaxadiol (2), 3-oxo-7β,23α-dihydroxyl-20(R)-panaxadiol (3), 3,12-dioxo- 7β,23β-dihydroxyl-20(R)-panaxadiol (4), 3-oxo-1α,7β-dihydroxyl-20(R)-panaxadiol (5) and 3-oxo-7β,15β-dihydroxyl-20(R)-panaxadiol (6) by spectroscopic analysis. Among them, compounds 2–6 were new compounds. Pharmacological studies revealed that compound 6 exhibited significant anti-hepatic fibrosis activity.     

Synthetic modifications in ethyl 2-amino-4-methylthiazole-5-carboxylate: 3D QSAR analysis and antimicrobial study

Ethyl 2-amino-4-methylthiazole-5-carboxylate (1) is a very substantial derivative of the thiazole group. This derivative has been modified and has been synthesized using readily available materials. The structures of synthesized derivatives were confirmed by IR, ¹H NMR, ¹³C NMR, and mass spectral techniques. The newly prepared compounds (5a–k) were studied for their antimicrobial activities against strains of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes) and fungi (Candida albicans, Aspergillus niger, and Aspergillus clavatus) using serial dilution method. Structure-activity relationship was carried out by CoMFA and CoMSIA with the help of 3D-QSAR analysis. As per the database alignment, the CoMFA and CoMSIA models were developed. Information based on these models is useful for structure-activity relationships of the reported molecules.     

Synthesis and antimicrobial activity of tetrazolo[1,5-a]quinoline-4-carbonitrile derivatives

Abstract  

A series of new tetrazolo[1,5-a]quinoline-4-carbonitrile derivatives were synthesized for the first time via tetrazolo[1,5-a]quinoline derivatives. Elemental analysis, IR, ¹H NMR, ¹³C NMR, and mass spectral data were used to elucidate the structures of all newly synthesized compounds. In vitro antimicrobial activities of synthesized compounds were investigated against Gram-positive Bacillus subtilis, Gram-negative Escherichia coli, and two fungi, Candida albicans and Aspergillus niger, in comparison with standard drugs. Some of the tested compounds showed significant antimicrobial activity.     

Novel synthesis of thieno[2,3‐b]pyridine and substituted 2‐thienylthiourea derivatives as antibiotic agents

Derivatives of thieno[2,3‐b]pyridine, 2‐thienylthiourea, 2‐thienylurea, 2‐thienylacetamide incorporating the 2‐phthalimidomethyl moiety have been synthesized. The synthesized compounds were then investigated for antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The compounds were also investigated for antifungal activity against Aspergillus niger and Fusarium oxysporium. The structures of the newly synthesized compounds have been established on the basis of their analytical and spectral data.