Synthesis and Antimicrobial Activity of 5-Imidazolinone Derivatives

Several 4-arylidene-2-phenyl-1-(2,4,5-trichlorophenyl)-1H-imidazol-5(4H)-ones (4a-q), N-(4-benzylidene-5-oxo-2-phenyl-4,5-dihydroimidazol-1-yl)-4-chlorobenzamides (5a-o) and N-(4-benzylidene-5-oxo-2-phenyl-4,5-dihydroimidazol-1-yl)-2,4-dichlorobenzamides (6a-m) were prepared. All newly synthesized compounds have been tested for their antibacterial activity against gram (+)ve and gram (−)ve bacteria and also on different strains of fungi. Introduction of OH, OCH₃, NO₂, Cl and Br groups to the heterocyclic frame work enhanced antibacterial and antifungal activities.     

Synthesis and Antimicrobial Activity of New Furan Derivatives

5-Nitrofuran derivatives were synthesized and their antibacterial activity was investigated using standard bacterial strains and clinical isolates. The compounds showed inhibitory effects on both Gram-positive and Gram-negative organisms.     

Synthesis and Antimicrobial Activity of Some New Quinazolin-4(3H)-one Derivatives

A new series of 6-iodo-2-phenylquinazolin-4(3H)-one derivatives was prepared and screened for antimicrobial activity. The thioureide derivatives 4–6, the carbohydrazide derivatives 19–21 and 24 displayed excellent broad-spectrum antimicrobial activity. Some compounds showed moderate activity against Candida albicans and Pseudomonas aeruginosa. None of the tested compounds was as active as the reference standard drugs ampicillin and clotrimazole. The detailed synthesis, antimicrobial activity, and the minimum inhibitory concentrations (MIC) are reported.     

Synthesis of Some New Antimicrobial Thiadiazolyl and Oxadiazolyl Quinoline Derivatives

Two series of substituted thiadiazolyl and oxadiazolylquinolines (3a-h, 4a-h, 7a-f, 8a-f and 9) were synthesized and screened for their antimicrobila activity. Some of the tested compounds showed promising activity. Compound 4b exhibited bactericidal activity agains S. aureus at 31.25 μg/ml. While compound 8a showed distinct antifungal activity against C. albicans (MIC at 31.25 μg/ml). The detailed synthesis, spectroscopic and biological data are reported.     

Synthesis and Antimicrobial Activity of Some New Anilino Benzimidazoles

A series of 2-(anilino or 2,6-dichloroanilino)-1,5(6)-disubstituted-1H-benzimidazoles ( 1–43 ) were prepared by reaction of several 2-chloro- or 2-chloromethyl-1H-benzimidazoles with aniline derivatives. The prepared compounds were screened for their in vitro antibacterial and antifungal activities. Compounds 2, 8 , and 9 exhibited the best activity.     

Cytotoxicity and Antimicrobial Activity of Some Naphthol Derivatives

2-Hydroxymethyl-1-naphthol diacetate (TAC) and sixteen Mannich base derivatives of naphthol were prepared and examined for cytotoxicity and antimicrobial activity. Cytotoxicity was examined against four human carcinoma cell lines. Several derivatives were effective at concentrations < 4 μg/ml. TAC showed the highest cytotoxicity. Inhibition of DNA-, RNA-, and protein synthesis by TAC was also studied and discussed. TAC also exhibits potent antimicrobial activity against Enterobacter clocae 23355, Klebsiella pneumonia 13883, Proteus vulgaris 13315, Pseudomonas aeruginosa 27853, Candida parapsilosis, Candida tropicalis, Trichosposon beigelli, and Rhodotorul spp. with minimum inhibitory concentrations of 0.1 ∼ 0.4 μM. These results indicate that esterification by Bruson reaction of 1-naphthol Mannich base to TAC enhances the cytotoxicity and antimicrobial activity.     

Synthesis of New 7-Substituted 4-Methylcoumarin Derivatives of Antimicrobial Activity

New cyclic derivatives derived from 4-methyl-7-coumarinyloxyacetic acid hydrazide have been synthesized. Some representative examples were screened for antimicrobial activity.     

Regioselective Synthesis,Characterization, and Antimicrobial Activities of Some New Monosaccharide Derivatives

A regioselective acylation series of methyl α-D-glucopyranoside (1), methyl 3-O-benzoyl-4,6-O-benzylidene-α-D-mannopyranoside (1A), and methyl 4,6-O-benzylidene-2-O-(3,5-dinitrobenzoyl)-α-D-mannopyranoside (1B) has been carried out by the direct acylation method and afforded the 2,6-di-O-glucopyranoside and 2 or 3-O-mannopyranoside derivatives in an excellent yield. In order to obtain newer products, the 2,6-di-O-glucopyranoside derivative was further transformed to a series of 3,4-di-O-acyl derivatives containing a wide variety of functionalities in a single molecular framework. The structures of the newly synthesized compounds were elucidated on the basis of IR, ¹H-NMR, ¹³C-NMR, ¹³C-DEPT spectral data, and elemental analysis. These synthesized derivatives were screened for in vitro antimicrobial activities against ten human pathogenic and five phytopathogenic microorganisms. A number of test compounds showed remarkable antimicrobial activity comparable to, and in some cases even higher than, the standard antibiotics employed. It was observed that methyl 3,4-di-O-(3-chlorobenzoyl)-2,6-di-O-hexanoyl-α-D-glucopyranoside (8) exhibited a varied range of MIC from 12.5 μg/disc to 25 μg/disc by the disk diffusion method and 1000 μg/mL to 1250 μg/mL by the broth macrodilution method.     

Synthesis and Evaluation of N-substituted Imidazole Derivatives for Antimicrobial Activity

A series of N-substituted imidazole derivatives was synthesized. Imidazole nucleus was reacted with ethylchloroacetate to form imidazole ester. Reaction of the imidazole ester (I) with different amines yields the desired products (1a- 1e). The compounds were characterized by FT-IR, ¹H-NMR and mass spectra. The synthesized compounds were evaluated for the antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger by determination of MIC (minimum inhibitory concentration) using tube dilution method. Compound (1b) was found to be the most active antimicrobial compound amongst others in the series.     

Synthesis of Pyrimidine Incorporated Piperazine Derivatives and their Antimicrobial Activity

Thiophene substituted chalcones (1a-e) were cyclised with thiourea in presence of potassium hydroxide to get 4-substituted-6-(thiophen-2-yl)pyrimidine-2-thiols (2a-e) which were then stirred with methyl iodide to obtain 4-substituted-2-(methylsulfanyl)-6-(thiophen-2-yl)pyrimidines (3a-e). Compounds (3a-e) were refluxed with different N-methylpiperazine and N-phenylpiperazine to afford 4-substituted-2-(4-methylpiperazin-1-yl)-6-(thiophen-2-yl)pyrimidines (4a-e) and 4-substituted-2-(4-phenylpiperazin-1-yl)-6-(thiophen-2-yl)pyrimidines (5a-e). The structures of all the newly synthesised compounds 4b, 4d, 5a and 5b showed good antibacterial activity at 40μg/mlconcentration. Compounds 4a, 4d, 4e, 5c and 5e showed significant antifungal activity at 40 μg/ml concentration compared with standard drugs.     

磺胺噻二嗪硫酮衍生物的合成及其抑菌活性

利用药物化学骈合原理设计并合成了一系列新的３，５－二取代１，３，５－噻二嗪－２－硫酮类化合物，其结构经红外光谱，紫外光谱及元素分析证实，抑菌活性试验显示了良好的抑菌活性。     

组合化学方法合成1，3，5-三嗪类化合物及其抗菌活性研究

基于天然或合成抗菌肽具有疏水性及带正电荷的特性,本研究以1,3,5-三嗪作为母体,利用组合化学方法合成了一系列三嗪衍生物。抗菌试验证明这些衍生物具有很强的抗菌活性和低溶血性,并能在低于最低抑菌浓度的情况下有效抑制细菌生物膜的生长。     

Efficient Electrochemical Synthesis, Antimicrobial and Antiinflammatory Activity of 2-amino-5-substituted- 1,3,4-oxadiazole Derivatives

An efficient electrochemical method for the preparation of 2-amino-5-substituted-1,3,4-oxadiazoles (4a-k) at platinum anode through the electrooxidation of semicarbazone (3a-k) at controlled potential electrolysis has been reported in the present study. The electrolysis was carried out in the acetic acid solvent and lithium perchlorate was used as supporting electrolyte. The products were characterized by IR,(1)H-NMR,(13)C-NMR, mass spectra and elemental analysis. The synthesized compounds were screened for their in vitro growth inhibiting activity against different strains of bacteria viz., Klebsilla penumoniae, Escherichia coli, Bassilus subtilis and Streptococcus aureus and antifungal activity against Aspergillus niger and Crysosporium pannical and results have been compared with the standard antibacterial streptomycin and antifungal griseofulvin. Compounds exhibits significant antibacterial activity and antifungal activity. Compounds 4a and g exhibited equal while 4c, d, i and j slightly less antibacterial activity than standard streptomycin. Compounds 4a and g exhibited equal while 4b, c, d, f and i displayed slightly less antifungal activity than standard griseofulvins.     

Synthesis and Antimicrobial Activity of 3-Aryl-5-hydroxy-5-methyl-2,4-di(methoxycarbonyl)cyclohexanones and Their Derivatives

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