Synthesis and antimicrobial screening of 1,3,4-oxadiazole and clubbed thiophene derivatives

In the present study, a novel series of 2-{5-[4-(1-aza-2-(2-thienyl)vinyl)phenyl](1,3,4-oxadiazol-2-ylthio)}-N-arylacetamides (IV)_1–12 were synthesized and tested for their antimicrobial activity. Newly synthesized compounds were screened for their antibacterial and antifungal activities on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus pyogenes, Candida albicans, Aspergillus niger and Aspergillus clavatus. The chemical structures of newly synthesized compounds were elicited by IR, ¹H NMR, ¹³C NMR and mass spectral data. The synthesized bio-active compounds exhibited excellent to moderate antimicrobial activity. Compounds (IV)₅, (IV)₆ and (IV)₇ possess excellent antibacterial activity whereas compounds (IV)₆, (IV)₉ and (IV)₁₁ possess excellent antifungal activity.     

Design,synthesis and biological evaluation of novel N1,N8-bis(((4-((5-aryl-1,3,4-oxadiazol-2-yl)methoxy)phenyl)amino)oxy)-1-naphthamide derivatives

A new series of 1,8-bis(4-((5-phenyl-1,3,4-oxadiazol-2-yl) methoxy)-substituted aryl) naphthalene-1,8-dicarboxamide derivatives (6a–j) were synthesized in the presence of POCl₃ and obtained good yields. All the synthesized novel compounds were characterized by IR, ¹H NMR, ¹³C NMR, HRMS spectroscopic data and elemental analysis. All the synthesized compounds evaluated for their antibacterial and antifungal activities. The antibacterial activity screened against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and used standard reference drug ciprofloxacin. The antifungal activity screened against two pathogenic fungal strains Aspergillus niger and Candida albicans used a reference standard drug Voriconazole. All these compounds (6a–j) demonstrate good antibacterial and antifungal activity. Among them, compounds 6h and 6c show highest antibacterial and antifungal activity.     

Synthesis and biological evaluation of 4-thiazolidinone derivatives as antitubercular and antimicrobial agents

New series of N-[2-{2-(substitutedphenyl)-4-oxo-5-(substitutedbenzylidene)-1,3-thiazolidine}-iminoethyl]-2-amino-5-nitrothiazole, 5(a–m) have been synthesized from 2-amino-5-nitrothiazole as a starting material by conventional as well as microwave methods. All the synthesized compounds 4(a–m) were screened for their antibacterial and antifungal activities against some selected bacteria and fungi and antitubercular activity screened against Mycobacterium tuberculosis. The structure of all the synthesized compounds were confirmed by chemical and spectral analyses such as IR, ¹H NMR, ¹³C NMR and FAB-Mass.     

Design,synthesis, molecular docking,and biological evaluation of novel selenium containing lumefantrine analogues

A new series of 1-(9-benzylidene-2,7-dichloro-9H-fluoren-4-yl)-2-(methylselanyl)ethanol was synthesized by a simple Knoevenagel condensation of 1-(2,7-dichloro-9H-fluoren-4-yl)-2-(methylselanyl)ethanol with different substituted aromatic aldehydes in basic media. These synthesized compounds were confirmed on the basis of their elemental analyses, infrared (IR), ¹H NMR, ¹³C NMR, and mass spectral data and screened for the antibacterial and antifungal activity. The preliminary antibacterial and antifungal screening revealed that the compounds 8c (dichloro), 8d (fluoro), 8e (chloro), 8i (methoxy), and 8l (methyl) displayed moderate to good activity. The antibacterial results of these compounds were further supported by in silico molecular docking studies, for the inhibition of Escherichia coli MurB enzyme (PDB code: 2MBR), wherein they showed higher binding energy and good affinity towards the active pocket of the enzyme compared with that of the standard drug Ciprofloxacin. Thus, the plausible mechanism of their antibacterial activity was owed to their inhibitory action of the bacterial MurB enzyme.     

Microwave-Assisted Synthesis of 2-Long Alkenyl Chain Benzoxazoles and Naphtho[2,3-d]oxazoles and Their Antimicrobial Evaluation

A microwave-assisted combinatorial synthesis of 2-long alkenyl chain benzoxazoles and naphtho[2,3-d]oxazoles with a catalytic amount of phosphorus pentasulphide at ambient pressure has been developed. This procedure constitutes a simple, practical, and green synthetic method for benzoxazoles and their structural analogs. All the compounds [2(a–d) through 6(a–d)] have been screened for antibacterial and antifungal activity. The compounds have showed good activity against Gram-positive and Gram-negative bacteria. All the compounds have also showed good results against almost all fungal strains. The structures of the synthesized compounds are elucidated by IR, ¹H NMR, ¹³C NMR, MS data, and elemental analysis.     

Synthesis of some Mannich base derivatives and their antimicrobial activity study

A series of 2-(phenyl)-2-(morpholin-4-yl)-N-phenylacetamide I–VII were synthesized by Mannich base method. Synthesized compounds I–VII were confirmed by IR, ¹H NMR, ¹³C NMR, mass and elemental analyses. Synthesized compounds I–VII were screened for antibacterial activity against various bacterial strains and compared with standard Ciprofloxacin at concentration 100 μg/mL and for antifungal activity against various fungal strains and compared with Clotrimazole at concentration 100 μg/mL; particularly 3-(4-chlorophenyl)-3-(morp holin-4-yl)-N-phenylpropanamide lll that has high antibacterial activity against Streptococcus epidermidis was compared with standard Ciprofloxacin.     

Synthesis,antimicrobial evaluation,and docking studies of some novel benzofuran based analogues of chalcone and 1,4-benzodiazepine

A series of novel {5-[4-hydroxy-3-(4-phenyl-2,3-dihydro-1H-benzo[b][1,4]diazepin-2-yl)benzyl]- benzofuran-2-yl}(phenyl)methanones (5a–5g) were prepared by the condensation of (E)-3-{5-[(2- benzoylbenzofuran-5-yl)methyl]-2-hydroxyphenyl}-1-phenylprop-2-en-1-one (chalcone) (4a) with various substituted o-phenylene diamines in the presence of oxalic acid as catalyst. The structures of all compounds were characterized by FTIR, ¹H NMR, ¹³C NMR, and MS. The representative examples were screened in vitro for antimicrobial activity. Among all compounds 4g and 5g showed potent antibacterial activity, 4b and 5g showed good antifungal activity. The data was further compared with structure based investigations using docking studies with the crystal structure of adenosine-5'-(β,γ-imido)triphosphate (2ONJ) from Staphylococcus aureus for antibacterial activity and trypsin (1FY5) protein from Fusarium oxysporum for the antifungal activity. The score values estimated by genetic algorithm were found to have a good correlation with the experimental inhibitory potencies.     

Synthesis,characterization and in vitro antimicrobial screening of quinoline nucleus containing 1,3,4-oxadiazole and 2-azetidinone derivatives

A series of 3-chloro-1-(aryl)-4-(2-(2-chloro-6-methylquinolin-3-yl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-4-ethyl-azetidin-2-ones (V)_1–12 have been synthesized and characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. Synthesized compounds were screened for their antibacterial activity against four different strains like Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes, while antifungal activity was determined against three different strains like Candida albicans, Aspergillus niger and Aspergillus clavatus. On the basis of statistical analysis, it has been observed that compounds gave significant co-relation.     

Synthesis and Antimicrobial Evaluation of Halogen-Containing Arylidene Thiazolo Triazinediones

A series of 7-substituted arylidene-1,3-thiazolo[2,3-c]-1,2,4-triazine-4,6-diones were synthesized in an one-pot multicomponent reaction of 6-arylmethyl-3-mercapto-1,2,4-triazin-5-ones with substituted benzaldehydes and monochloroacetic acid in the presence of acetic anhydride, acetic acid, and sodium acetate. The structures of the new compounds were supported by IR, ¹H NMR, MS, and analytical data. All the new compounds were tested for their antibacterial and antifungal activity. Arylidene thiazolo triazinediones with 1,3-benzodioxolo substituent at seventh and p-chlorophenyl or 2,4-dichlorophenyl substituents at third displayed good antibacterial and antifungal activity. And also compound bearing 2,3,5-trimethoxyphenyl substituent at seventh and 2,4-dichlorophenyl substituent at third displayed good activity.     

Synthesis and biological activities of novel ethers of quinolinone linked with coumarins

Abstract  

A series of new ethers of quinolinone linked with different substituted coumarins and benzofurans were synthesized from 4-(bromomethyl)quinolinones. All newly synthesized compounds were screened for their in vitro antibacterial and antifungal activities. Most of the compounds with chloro substitution at the C-6 or C-7 position in quinolinone showed potent antibacterial and antifungal activities. In pharmacological evaluations, some of these chloroquinolinones also showed 70–77% inhibition of inflammation after 8 h, whereas the other compounds showed 51–55% inhibition. Most of the compounds showed potent analgesic activity compared to the standard and control. The structures of all newly synthesized compounds were characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, and EI-MS.     

Synthesis,Antimicrobial, and Brine Shrimps Lethality Assays of 3,3‐Diaryl‐4‐(1‐methyl‐1H‐indol‐3‐yl)azetidin‐2‐ones

The paper describes the synthesis, characterization data, and biological activity (antibacterial, antifungal, and brine shrimps lethality) of new azetidin‐2‐ones. The compounds have been synthesized by the reaction of diarylketenes, generated in situ from thermal decomposition of the 2‐diazo‐1,2‐diarylethanones, with N‐(1‐methyl‐1H‐indol‐3‐yl)methyleneamines. The compounds have been characterized by elemental analysis and spectral (IR, ¹H and ¹³C NMR, and MS) data. The paper also reports the results of antibacterial, antifungal, and brine shrimps lethality assays of these compounds. Some of the compounds exhibited significant biological activity.     

Synthesis,Dissociation Constants,and Antimicrobial Activity of Novel 2,3‐Disubstituted‐1,3‐thiazolidin‐4‐one Derivatives

In this article, a new series of 2,3‐disubstituted‐1,3‐thiazolidin‐4‐one derivatives have been designed, synthesized, and evaluated as antimicrobial agents. New compounds were prepared by the cyclization reaction of N‐substituted carboxylic acid hydrazide derivatives with mercaptoacetic acid. The structures of the obtained compounds were confirmed by means of IR, ¹H NMR, and ¹³C NMR spectra. The dissociation constants were determined using spectrophotometric method. All synthesized compounds were tested for their in vitro antibacterial and antifungal activities using the broth microdilution method.     

Synthesis,Characterization, and Biological Activity of Substituted Thiazole-5-carboxaldehydes and Their Ylidenenitriles Derivatives

The Vilsmeier–Haack reaction of 2-amino -4-(4-substituted phenyl)-thiazoles 1, in the presence of micellar media, gives formylated derivatives 2, which upon hydrolysis afforded thiazole-5-carboxaldehydes 3. Microwave-assisted Knoevenagel condensation of 3 with active methylene compounds, in the presence of piperidine as catalyst, gives excellent yields of ylidenenitrile compounds 4. The structures of the newly synthesized compounds were established on the basis of elemental analysis, IR, ¹H NMR, and ¹³C NMR spectral analysis. All newly synthesized compounds were screened for antibacterial activity using two Gram-positive and one Gram-negative bacterial species and their antifungal activity was screened using two fungal species.     

Synthesis and Evaluation of Antimicrobial Activity of Some New Hetaryl‐Azoles Derivatives Obtained from 2‐Aryl‐4‐methylthiazol‐5‐carbohydrazides and Isonicotinic Acid Hydrazide

A series of new 1,3,4‐oxadiazole/thiadiazole and 1,2,4‐triazole derivatives have been synthesized starting from 2‐aryl‐4‐methylthiazol‐5‐carbohydrazides and isonicotinic acid hydrazide. All the newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectrometry. The synthesized compounds were screened for their antibacterial and antifungal activity, assessed as growth inhibition diameter. Some of them showed good antibacterial activity against gram positive Staphylococcus aureus, while the antibacterial activity against Listeria monocytogenes, Escherichia coli, and Salmonella typhymurium and antifungal activity against Candida albicans was modest. None of the tested compounds showed inhibitory activity against gram positive bacteria Enterococcus faecalis and Bacillus cereus and against gram negative bacteria Pseudomonas aeruginosa.     

Synthesis,spectral characterization and biological evaluation of novel 1-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl)ethyl)piperazine derivatives

A simple, highly useful synthesis of 1-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl)ethyl)piperazine derivatives is achieved by a four component cyclo condensation of diacetyl, aromatic aldehyde, 2-(piperazin-1-yl)ethanamine and ammonium acetate using SO₄²⁻/Y₂O₃ as a catalyst in ethanol. The synthesized compounds were characterized by IR, ¹H and ¹³C NMR and mass spectral studies. All the synthesized compounds were screened for their in vitro antimicrobial studies. Among the newly synthesized compounds 5d, 5e, 5h and 5m showed excellent antibacterial and antifungal activities when compared to the standard drugs.     

Solvent-free microwave assisted synthesis of morpholine–piperidine–pyrrolidine annulated quinoline-naphthyl based chalcones and their antimicrobial activity

A new series of 2-morpholine–piperidine–pyrrolidine substituted quinoline based chalcones have been synthesized by conventional and microwave irradiation methods. All synthesized compounds were characterised by IR, ¹H and ¹³C NMR, mass spectrometry, and elemental analysis. The products were evaluated in vitro for antibacterial activity against two bacterial strains (Staphylococcus aureus, Escherichia coli) and antifungal activity against two fungal strains (Aspergillus flavus, Candida metapsilosis). 2-Piperidine substituted quinoline chalcones demonstrated high antimicrobial activity.     

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.     

Synthesis and antibacterial activity of novel pyrano[2,3-d]pyrimidine-4-one–3-phenylisoxazole hybrids

A series of ethyl 2,7-dimethyl-4-oxo-5-phenyl-3-[(3-phenylisoxazol-5-yl)methyl]-3,5-dihydro-4H-pyrano[2,3-d]pyrimidine-6-carboxylates was synthesized and screened for antibacterial activity against Gram positive and Gram negative bacterial species. All new compounds were characterized by ¹H, ¹³C NMR, IR, and mass spectra. The results of the antibacterial study indicated that all compounds exhibited good to excellent antibacterial activity.

     

Synthesis and antimicrobial agents of thiazolidinone derivatives from benzocyclohepetenone

A series of benzosuberone coupled piperazin-1-yl thiazolidin-4-one derivatives 6a-j were synthesized from 3-(2-[9-chloro-2,3-dimethyl-6,7-dihydro-5H-benzo[7]annulen-8-yl]-4-oxothiazolidin-3-yl)propanoic acid ( 4 ) and substituted piperazines/secondary amines 5a-j using 1-hydroxy benzotriazole, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and triethyl amine in good yields and their structures were characterized by ¹H NMR, ¹³C NMR, IR, and Mass spectra. The newly synthesized compounds were evaluated for their antimicrobial activity against bacterial strains and a fungal strain. Compounds 6f and 6g were indicated promising and broad spectrum antibacterial activity.     

Synthesis,characterization and antimicrobial evaluation of novel halopyrazole derivatives

Two novel halopyrazole derivatives (3, 5) were synthesized from 5-chloro-3-methyl-1-phenylpyrazole-4-carboxaldehyde (1) using appropriate synthetic routes. Newly synthesized compounds were characterized using elemental analysis, spectral data (IR, ¹H NMR, ¹³C NMR and mass spectrometry) and were evaluated for their in vitro antimicrobial activity. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were determined for the test compounds as well as for reference standards. The investigation of antimicrobial screening revealed that compounds (3, 5) showed good antibacterial and antifungal activities, respectively.