Syntheses and evaluation of 2,5-disubstituted 4-thiazolidinone analogues as antimicrobial agents

Two novel series of 4-thiazolidinone derivatives, bearing 2-nitrophenyl imino and 4-nitrophenyl imino groups at position-2 and substituted arylidene groups at position-5, have been synthesized and evaluated for antimicrobial activity against four bacterial and one fungal strain. The success of the synthesis of compounds was confirmed on the basis of spectral analysis. All the newly synthesized compounds were obtained in high yields and exhibited good antibacterial activity; however, the antifungal potential was limited to a few agents.     

Synthesis of 4-hydroxycoumarin heteroarylhybrids as potential antimicrobial agents

A new series of 4-hydroxycoumarin derivatives 3a-d was synthesized by the reaction of 3-bromo-4-hydroxy coumarin 1 with various heteroaldehydes 2a-d in good yields. The synthesized compounds were characterized on the basis of their elemental and spectral (IR, (1)H-NMR and mass spectrometry) analysis. All target compounds were evaluated for their in-vitro antimicrobial activity against Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli bacterial strains and fungal cultures of Candida albicans, Aspergillus fumigatus, Trichophyton mentagrophytes, and Penicillium marneffei by disk diffusion assay with slight modifications. The minimum inhibitory concentration (MIC) was determined for the test compounds as well as for reference standards. Among the tested compounds, 3a has shown the most potent antibacterial as well as antifungal activities.     

Synthesis of new potential anticancer agents based on 4-thiazolidinone and oleanane scaffolds

The synthesis and evaluation of the anticancer activity of new acylated oximes derivatives of oleanolic acid with 4-thiazolidinone-3(5)-carboxylic acid moieties were described. Newly synthesized compounds were elucidated on the basis of elemental analyses and spectral data (IR, ¹H, and ¹³C NMR). Anticancer activity of the tested compounds has been evaluated in vitro at National Cancer Institute (NCI) in which some structure activity relationships (SARs) were discussed. Among the tested compounds, 3-[(2,4-thiazolidinedione-5-ylidene)-carboxyimino]olean-12-en-28-oic acid methyl ester (IVm) was superior to other related compounds with mean values of pGI₅₀?=?5.51/5.57, pTGI?=?5.09/5.13, and pLC₅₀?=?4.62/4.64, low toxicity and moderate activity level in vivo hollow fiber assay.     

Synthesis of 4-substituted aminoquinoline-3-carboxylates as potential antimicrobial agents

A series of 4-substituted aminoquinoline-3-carboxylates was prepared and evaluated for antimicrobial activity. Four of the compounds (VIII, XIII, XV, and XXIII) exhibited low activity against Staphylococcus aureus.     

Synthesis of some novel 4-arylidene pyrazoles as potential antimicrobial agents

Background

Pyrazole and pyrazolone motifs are well known for their wide range of biological activities such as antimicrobial, anti-inflammatory, and antitumor activities. The incorporation of more than one pharmacophore in a single scaffold is a well known approach for the development of more potent drugs. In the present investigation, a series of differently substituted 4-arylidene pyrazole derivatives bearing pyrazole and pyrazolone pharmacophores in a single scaffold was synthesized.

Results

The synthesis of novel 4-arylidene pyrazole compounds is achieved through Knovenagel condensation between 1,3-diaryl-4-formylpyrazoles and 3-methyl-1-phenyl-1H-pyrazol-5-(4H)-ones in good yields. All compounds were evaluated for their in vitro antimicrobial activity.

Conclusions

A series of 4-arylidene pyrazole derivatives was evaluated for their in vitro antimicrobial activity against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Pseudomonas fluorescens and Escherichia coli), as well as two pathogenic fungal strains (Candida albicans and Saccharomyces cerevisiae). The majority of the compounds displayed excellent antimicrobial profile against the Gram-positive (B. subtilis and S. aureus), and some of them are even more potent than the reference drug ciprofloxacin.

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New pyridine derivatives as potential antimicrobial agents

A set of pyridine derivatives bearing a substituted alkylthio chain or a piperidyl ring in position 2 or 4 were synthesized, and their antimycobacterial and antifugal activities were evaluated. Chemical structures were confirmed by IR and NMR data, and by elemental analysis. Minimum inhibitory concentrations (MIC) were used for the evaluation of microbiological activity in vitro. The compounds were moderately active against both Mycobacterium tuberculosis and nontuberculous mycobacteria. The most active compound was 2-cyanomethylthiopyridine-4-carbonitrile (7) with MIC against Mycobacterium kansasii in the range of 8-4 mumol/l. The antifungal activities of the compounds were relatively low.     

Design, synthesis, and biological evaluation of new 4-thiazolidinone derivatives substituted with benzimidazole ring as potential chemotherapeutic agents

In search of novel antiviral and anticancer agents with promising pharmacotoxicological profile, a study was initiated to synthesize new 2-thioxo-4-thiazolidinones as well as 2-phenylimino-4-thiazolidinones substituted with benzimidazole ring system. The compounds were screened primarily for their antiviral as well as anticancer activities. The synthesis of some novel 5-substituted thiazolidinones was also described. None of the tested compounds showed inhibitory activity against Hepatitis C virus replication. Two 2-phenylimino-4-thiazolidinone derivatives (9a and 10) exhibited significant antiproliferative activity against human colon carcinoma cell line HCT 116 and human hepatocellular carcinoma HEPG2 cell line, respectively. Results also indicated that six thiazolidinone derivatives (5a, 5d, 5e, 5f, 5h, and 9d) showed moderate antiproliferative activity against human breast adenocarcinoma cell line MCF7 in comparison to the standard drug Doxorubicin. Moreover, a docked pose of the most potent three cytotoxic compounds 5a, 5h, and 9d against MCF7 was obtained bound to Human N-acetyl transferase1 NAT1 binding pocket by molecular operating environment module.     

Synthesis of some new glutamine linked 2,3-disubstituted quinazolinone derivatives as potent antimicrobial and antioxidant agents

A series of novel glutamine linked 2,3-disubstituted quinazolinone conjugates was synthesized from methyl anthranilate and different substituted acids and acid chlorides. The compounds 5a–l were prepared in good yields. All compounds were screened for their antibacterial activity against Gram-positive and Gram-negative bacteria and for antifungal activity against Candida albicans and Aspergillus flavus using paper disk diffusion technique. The minimum inhibitory concentrations of the compounds were also determined by agar streak dilution method. The compound 5b was found to exhibit the most potent in vitro anti-microbial activity. When tested for their antioxidant activity, compounds 5i and 5l showed potent radical scavenging activity, while compound 5g had moderate effect against 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, nitric oxide, and superoxide radical scavenging assays. These results suggest that, the three quinazolinone analogs (5g, 5i, and 5l) could be considered as useful templates for future development to obtain more potent antioxidant agents.     

Benzimidazolyl quinolinyl mercaptotriazoles as potential antimicrobial and antiviral agents

Condensation of ethylaceto acetate (EAA) with resorcinol in concentrated H2SO4 afforded 7-hydroxy-4-methyl coumarin (1), which on reaction with thiosemicarbazide in anhydrous pyridine yielded 7-hydroxy-4-methyl-quinolinyl [1,5-c]-mercaptotriazole (2). Reaction of 2 with formaldehyde solution and amino acid in ethanol yielded 7-hydroxy-4-methyl-8-(N-methyl-aminoacid)-quinolinyl [1,5-c]-2'-mercaptotriazole (3a-e). Interaction of 3 with o-phenylenediamine in pyridine yielded 7-hydroxy-4-methyl-8-(aminobenzimidazolyl)-quinolinyl [1,5-c]-2'-mercaptotriazole derivatives (4a-e). The latter compounds were evaluated for their antiviral and antimicrobial activities.     

Synthesis of benzimidazole derivatives as potential antimicrobial agents

Three novel series of benzimidazol derivatives were prepared. Namely; 2-alkyl-1-(4-substituted-4H-1,2,4-triazole-5-thion-3-yl)methylb enzimidazoles; 2-alkyl-1-(5-substituted amino-1,3,4-thiadiazol-2-yl)methylbenzimidazoles; and 2-alkyl-1-[(3,4-disubstituted thiazolin-2-ylidene)hydrazinocarbonyl] methylbenzimidazoles. The antimicrobial testing of the prepared compounds as well as of the key intermediate thiosemicarbazides was performed.     

Synthesis of alkyloxybenzamide derivatives as potential antimicrobial agents

Three series of alkyloxybenzamido derivatives have been prepared. The first comprises N1-[4-(4-alkyloxybenzamido)benzoyl]-N2-substituted alkylidene hydrazine, the second involves 1-[4-(4-alkyloxybenzamido)benzoyl]-4-alkyl, aryl, or aralkyl-3-thiosemicarbazides, and the third includes 1-substituted-5-[4-(4-alkyloxybenzamido)phenyl]-1,3,4-triazole-2-t hione. Representative samples of the prepared compounds were tested for their in-vitro antimicrobial activity.     

Arylidenepyruvic acid thiosemicarbazone and thiazoline derivatives as potential antimicrobial agents

Two novel series of arylidenepyruvic acid thiosemicarbazone and thiazoline derivatives were synthesized and evaluated as potential antimicrobial agents. These substances did not exhibit any significant antibacterial effects when tested against a variety of microorganisms.     

Dimeric 2-(2-chlorophenyl)-quinazolin-4-ones as potential antimicrobial agents

3-(Aryl)-2-(2-chlorophenyl)-6-{2-[2-(2-chlorophenyl)-4-oxo(3-hydroquinazolin-3yl)]ethyl}-3-hydroquinazolin-4-ones had been selected as target bio-active molecules. Several quinazoline derivatives were prepared by using anthranilic acid, acid chloride, 2-amino-ethanol, and different amines. 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 compounds 5e, 5g, and 5h are shown to have excellent activity, while 5c, 5d, 5i, 5k, 5l are shown to have very good activity against several strains of bacteria. The structures of the synthesized compounds were firmly established by well-defined spectral analysis techniques like IR, ¹H-NMR, ¹³C-NMR, and Mass spectra.     

Novel pyrazole derivatives as potential promising anti-inflammatory antimicrobial agents

Four series of 1H-pyrazole derivatives have been synthesized. The first series was synthesized starting by condensing the hydrazine derivatives 1a-d with 4-(1-ethoxycarbonyl-2-oxopropyl)azobenzoic acid 2a in ethanol or glacial acetic acid to generate the corresponding pyrazoline derivatives 3a-d. Likewise, heating 1a-d with 4-(1-acetyl-2-oxopropyl)azobenzoic acid 2b gave rise to the pyrazole derivatives 4a-d. Similarly, reaction of 1a-d with ethyl 2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylazo)-3-oxobutanoate 2c or 3-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl azo)pentane-2,4-dione 2d in ethanol or glacial acetic acid led to the corresponding pyrazoline derivatives 5a-d or pyrazole derivatives 6a-d. The newly synthesized compounds were evaluated for their anti-inflammatory-antimicrobial activities. In addition, the ulcerogenic and acute toxicity profiles were determined. Compound 6c, proved to be the most active anti-inflammatory-antimicrobial agent in the present study with a good safety margin and no ulcerogenic effect.     

Synthesis and biological evaluation of novel benzoquinones as potential antimicrobial agents

New series of 2,5-dihydroxyphenyl-1,3-thiazoles 4a–l was synthesized by reacting 2,5-dihydroxyphenacyl bromide with various 4-aryl thiosemicarbazones 3a–l that on oxidation with ferric chloride yielded the corresponding N ¹-substituted benzylidene-N ²-[3-aryl-4-(1,4-benzoquinon-2-yl)-1,3-thiazol-2-ylidene]hydrazines 5a–l. They were evaluated for antibacterial activity against Staphylococcus aureus and Bacillus subtilis as Gram-positive bacteria, Escherichia coli and Pseudomonas aeruginosa as Gram-negative bacteria. They were also evaluated for their in vitro antifungal potential against Candida albicans. Almost all tested compounds were found to possess variable degrees of antimicrobial activity. The obtained data revealed that compounds 4b–h and 5e, 5f and 5l exhibited promising antimicrobial activity against the tested organisms of which compound 4b proved to be the most active.     

Synthesis and pharmacological evaluation of novel 4-isopropylthiazole-4-phenyl-1,2,4-triazole derivatives as potential antimicrobial and antitubercular agents

A series of novel 4-isopropylthiazol-4-phenyl-1,2,4-triazol derivatives, N′-(substituted benzylidene)-2-(5-(4-isopropylthiazol-2-yl)-4-phenyl-4H-1,2,4-triazol-3-ylthio)acetohydrazides 4a–e, 4-isopropylthiazol-2-yl-4′-phenyl-4′H-1′, 2′,4′-triazol-3′-ylthio (substituted methyl benzylidene) acetohydrazides 5a–f, 3-(4-isopropylthiazol-2-yl)-4-phenyl-5-(5-substituted-1,3,4-oxadiazol-2-ylthio)-4H-1,2,4-triazole derivatives 6a–f and N-acetyl-5′-(4-isopropylthiazol-2-yl)-4′-phenyl-4′H-1,2,4-triazol-3′-ylthio) acetohydrazide 7 were synthesized and characterized by spectroscopy, elemental, and mass spectral analysis. These compounds were evaluated for their preliminary in vitro antibacterial, antifungal, and antitubercular activity against Mycobacterium tuberculosis (M. tuberculosis) H37Rv strain by broth dilution assay method. All the compounds exhibited moderate to significant antibacterial and antifungal activities. Results of the antitubercular screening against Mycobacterium tuberculosis H37Rv showed that compounds 4c and 6c exhibited good antitubercular activity when compared with first line drug isoniazid.     

Synthesis of thiadiazol derivatives of 4(3H)-quinazolinone as potential antimicrobial agents

Three series of quinazolinone derivatives were synthesised namely: 3-[4-(2-substituted amino-1,3,4-thiadiazol-5-yl)phenyl]-2-methyl-4-(3H)- quinazolinones; 3-[4-(2-substituted amino-1,3,4-thiadiazol-5-yl)anilino]-2-methyl-4-(3H)- quinazolinones and 3-[(2-substituted amino-1,3,4-thiadiazol-5-yl)methyl]-2-methyl-4(3H)-quinazolinones. The antimicrobial activity of representative compounds of these series as well as of the starting quinazolinone acids was studied.     

Design and synthesis of some azole derivatives as potential antimicrobial agents

Syntheses of 1,2,4-triazol-3-ones, 4a, 4b, and 5 were performed starting from ester ethoxycarbonylhydrazones (1a, 1b) that were reported earlier. The treatment of triazole derivatives, 4a, 4b, and 5 with several sulfonyl halides produced the corresponding sulfonamides, 6–10. Syntheses of carbo(thio)amides, 15, 17, and 18 were carried out by the treatment of (substituted)phenyliso(thio)cyanates with hydrazides 13, 14 which were obtained starting from 4a and 5 by two steps. Cyclization of compounds 15 and 17 in basic media resulted in the conversion of carbo(thio)amide side chain to 5-oxo- or 5-mercapto-1,2,4-triazole ring. Cyclocondensation of 17 with ethyl chloroacetate and 4-nitrophenacylbromide gave 1,3-thiazolidin, 20 and 1,3-thiazol 21, derivatives, respectively. Newly synthesized compounds were screened for their antimicrobial activities, and some of them displayed activity against the test microorganisms. Then the highest activity was observed for compounds 6 and 7 carrying cyclic sulfonamide function beside 1,2,4-triazole nucleus.     

Synthesis of certain thiosemicarbazide and triazole derivatives as potential antimicrobial agents

Two novel series of thiosemicarbazide derivatives were synthesized: 2-[4-(substituted thiocarbamoylhydrazinocarbonyl) phenoxymethyl]-1H-benzimidazoles and 1-benzyl-2-[4-(substituted thiocarbamoylhydrazinocarbonyl) phenoxymethyl]-1H-benzimidazoles, and cyclised to 2-[4-(4-substituted-4H-1,2,4-triazole-5-thion-3-yl)phenoxymethy ]-1H-benzimidazoles and 1-benzyl-2-[4-(4-substituted-4H-1,2,4-triazole-5- 5-thion-3-yl)phenoxymethyl]-1H-benzimidazoles, respectively. The antimicrobial activity of the prepared compounds was tested.