Synthesis and evaluation of antibacterial activity of some 2-[[alpha-(4-substituted benzoyloxy)-alpha-phenylacetyl or methylacetyl]amino]-5-(4-methoxyphenyl)- 1,3,4-oxadiazoles

In this study, a new series of 1-[[alpha-(4-substitutedbenzoyloxy)-alpha-phenylacetyl or methylacetyl]amino]-5-(4-methoxyphenyl)-1,3,4-oxadiazoles were obtained by condensation of 2-[(alpha-chloro-alpha-phenylacetyl or alpha-bromopropionyl)amino]-5-(4-methoxyphenyl)1,3,4-oxadiazoles with sodium salts of 4-substituted benzoic acids. Structures of the compounds were assigned on the basis of spectral data (UV, IR, 1H NMR, El MS) and elemental analyses. The antibacterial activities of the novel compounds against Staphylococcus aureus ATCC 6538. Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa ATCC 1539, Salmonella typhi, Shigella flexneri and Proteus mirabilis and antifungal activity against Candida albicans ATCC 10231 were tested using disk diffusion method. Compounds 4a, 4d and 4g were found to be active against S. aureus ATCC 6538 (MIC, 78, 39 and 78 microg ml(-1), respectively) and compound 4e against S. epidermidis ATCC 12228 (MIC, 156 microg ml(-1)).     

Protection of carrageenin edema and trypsin hydrolysis of bovine serum albumin by naphthylthiosemicarbazides and their cyclized oxadiazoles.

Seven 1-(naphth-1-ylacetyl)-4-substituted thiosemicarbazides were synthesized and cyclized to the corresponding 2-(naphth-1-ylmethyl)-5-arylamino-1,3,4-oxadiazoles. All compounds, with the exception of two slbstituted oxadiazoles, possessed low anti-inflammatory activity. The protection afforded by these compounds against carrageen-in-induced edema ranged from 3 to 43% where cyclization, in general, decreased anti-inflammatory activity. All compounds (1 mM), possessed antiproteolytic activity where in vitro protection of trypsin-induced hydrolysis of bovine serum albumin, in most cases was greater with oxadiazoles.     

Synthesis of some new 2-(6-methoxy-2-naphthyl)- 5-aryl-1,3,4-oxadiazoles as possible non-steroidal anti-inflammatory and analgesic agents

The synthesis of some new 2-(6-methoxy-2-naphthyl)-5-aryl-1,3,4-oxadiazoles (4a-k) has been described. Ethyl-6-methoxy-2-naphthoate (1) yielded on treatment with hydrazine hydrate to 6-methoxy-2-naphthoic acid hydrazide (2). Compound 2 reacted with substituted aromatic carboxylic acids (3a-k) in phosphorus oxychloride yielded 2-(6-methoxy-2-naphthyl)-5-aryl-1,3,4-oxadiazoles (4a-k). Newly synthesized compounds were characterized by IR, (1)H-NMR and mass spectral data. All the compounds were screened for their anti-inflammatory and analgesic activity. Compound 4j exhibited promising anti-inflammatory and analgesic activities.     

Synthesis of Some New Substituted 1,3,4-Oxadiazoles as Potential Insecticidal,Antibacterial and Anti-acetylcholine Esterase Agents

A series of 5-substituted phenoxymethyl-2-[N-(2-alkyl-1,3,4-thiadiazol-5-yl)carbamoylmethylthio]-1,3,4-oxadiazoles have been synthesized. All compounds were tested for their insecticidal, antibacterial and anti-acetylcholine esterase activities. Most of the compounds exhibited significant biological activity. Structure-activity relationships have further been studied and are discussed.     

Synthesis and Reactions of 2(5)-[Benzyl or Cyanomethyl]-1,3,4-oxadiazoles

A series of five membered heterocycles, namely 5-(benzyl or cyanomethyl)-3-acetyl-2,2-disubstituted-1,3,4-oxadiazolines ( 3a-e ), 2,5-disubstituted-1,3,4-oxadiazoles ( 4a, b ), 2-hydroxy-5-(benzyl or cyanomethyl)-1,3,4-oxadiazoles ( 5a, b ), 1,2,5-trisubstituted-1,3,4-triazoles ( 6a, b ), and 2-(benzyl or cyano-methyl)-1,3,4-oxadiazole-5-thiols ( 10a, b ), were synthesized. Also 5-chloro-2-benzyl-1,3,4-oxadiazole 7 was prepared. Reaction of amines, hydrazines, and sodium azide with 7 gave the corresponding 2-arylamino ( 8a, b ), 5-hydrazino or phenylhydrazino ( 8c, d ) and 2-azido derivatives 9 , respectively. Mannich bases ( 11a, b ) were prepared by the reaction of sec. amines with 9a . 5-Carboxymethylthio-1,3,4-oxadiazoles ( 12a, b ) and their ethyl esters ( 13a, b ) were also prepared. The ester 13a reacted with amines and hydrazines to give the corresponding amides ( 14a-d ).     

Synthesis,biological evaluation,and molecular modeling of (<Emphasis Type="Italic">E</Emphasis>)-2-aryl-5-styryl-1,3,4-oxadiazole derivatives as acetylcholine esterase inhibitors

A library of 2,5-disubstituted 1,3,4-oxadiazole derivatives of (E)-2-aryl-5-(3,4,5-trimethoxystyryl)-1,3,4-oxadiazoles 4(a–o) and (E)-2-aryl-5-(2-benzo[d][1,3]dioxol-5-yl)vinyl)-1,3,4-oxadiazoles 5(a–q) were synthesized and evaluated for their in vitro acetylcholinesterase (AChE) inhibitory activity. All the synthesized compounds exhibited moderate to good inhibitory activity toward the AChE enzyme. Among the oxadiazole derivatives examined, compounds 4a, 4g, 5c, and 5m (IC₅₀ values of 24.89, 13.72, 37.65, and 19.63 μM, respectively) were found to be promising inhibitors of AChE. Molecular protein–ligand docking studies were examined for these compounds using GOLD docking software and their binding conformations were determined and the simultaneous interactions mode was also established for the potent derivatives.     

Synthesis and antimicrobial activity of some 5-aryl-2-[N,N-disubstituted thiocarbamoylthio)acylamino]-1,3,4-oxadiazoles

In this study, a number of novel 5-aryl-2-[(N,N-disubstituted thiocarbamoylthio)acylamino]-1,3,4-oxadiazole derivatives were synthesized by the reaction of potassium salts of N,N-disubstituted dithiocarbamoic acids with 2-[(alpha-chloro-alpha-phenylacetyl/alpha-bromopropionyl)-amino]-5 -aryl-1, 3,4-oxadiazoles. Structures of the compounds were confirmed by the spectral data (IR, 1H NMR, EIMS) and elemental analyses. Most of the compounds were tested against various microorganisms and four of them were found to be weakly active against Staphylococcus aureus and Staphylococcus epidermidis.     

Synthesis and antioxidant properties of some novel benzimidazole derivatives on lipid peroxidation in the rat liver

Some benzimidazole derivatives namely 1-[(substituted thiocarbamoylhydrazine carbonyl) methyl]-2-phenyl-1H-benzimidazoles (1a-13a), N-[(2-phenylbenzimidazol-1-yl methyl)-[1,3,4]-thiadiazole-2-yl]-substituted phenyl amines (1b-13b) and 5-(2-phenyl benzimidazol-1-yl-methyl)-4-substituted phenyl-4H-1,2,4-triazole-3-thiones (1c-13c) were synthesized, and their in vitro effects on the rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. The most active compound 10a caused an 84% inhibition of LP at 10(-3) M, which is better than that of butylated hydroxytoluene (BHT) (65%).     

Synthesis of some new 1-acylthiosemicarbazides, 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazole-3-thiones and their anti-inflammatory activities.

Sixteen 1-(1-naphthyloxy)acetyl-4-substituted-3-thiosemicarbazides, 2-substituted amino-5-(1-naphthyloxy)methyl-1,3,4-oxadiazoles, 2-substitutedamino-5-(1-naphthyloxy) methyl-1,3,4-thiadiazoles and 3-(1-naphthyloxy)methyl-4-substituted-1,2,4-triazole-5-thiones were synthesized. The structures of the compounds have been elucidated by UV, IR, 1H-NMR, 13C-NMR spectra and elemental analysis. The anti-inflammatory activities of the compounds were evaluated by carregeenan induced hind paw edema and air-pouch inflammation tests in mice. In carrageenan induced hind paw edema test, compounds 1a, 1d, 3d, 4a showed equivalent or higher activity compared to naproxen and phenylbutazone. In the air-pouch inflammatory model, compounds 1a, 1b, 1d, 2c, 3c, 3d, 4a and 4d showed marked anti-inflammatory activity. The ED50 values of these compounds ranged between 24-36 mg/kg. Side effects of the compounds on gastrointestinal system and kidneys were examined and none of the compound showed significant side effects.     

1,4-双[(5-芳基-1,3,4-噁二唑-2-)亚甲基]哌嗪的合成及其抗菌活性

目的研究多杂环化合物的合成方法和抗菌活性.方法将2-芳基-5-氯甲基-1,3,4-噁二唑(h～1n)与哌嗪缩合得相应的双取代哌嗪目标化合物(2a～2n).用试管稀释法,研究目标化合物的体外抑菌活性.结果合成了14个新化合物,其结构经MS、IR、1H-NMR和元素分析确证.多数化合物在体外表现出较好的抑菌活性.结论双噁二唑杂环取代的哌嗪化合物有可能成为新型结构的抗菌药物.     

Synthesis and antituberculosis activity of new N-phenyl-N'-[4-(5-alkyl/arylamino-1,3,4-thiadiazole-2-yl)phenyl]thioureas

In this study, eight original N-phenyl-N'-[4-(5-alkyl/arylamino-1,3,4-thiadiazole-2-yl)phenyl]thiourea derivatives were synthesized and tested for antituberculosis activity. Antituberculosis activities of the synthesized compounds were screened in vitro using BACTEC 460 Radiometric System against Mycobacterium tuberculosis H37Rv at 6.25 microg/ml. The highest inhibition observed with the synthesized compounds is 67% for N-phenyl-N'-[4-(5-cyclohexylamino-1,3,4-thiadiazole-2-yl)phenyl]thiourea.     

Synthesis and antioxidant capacities of some new benzimidazole derivatives

In this study, we prepared some new oxadiazolyl benzimidazole derivatives and investigated their antioxidant properties by determination of microsomal NADPH-dependent inhibition of lipid peroxidation levels (LP assay) and microsomal ethoxyresorufin O-deethylase activity (EROD assay). Some of these compounds 20, 23 had slightly inhibitory effects (28%) on the lipid peroxidation levels at 10(-3 )M concentration lower than standard BHT (65%). 5-[2-(Phenyl)-benzimidazol-1-yl-methyl]-2-mercapto-[1,3,4]-oxadiazole 16 was found to be more active than caffeine on the ethoxyresorufin O-deethylase activity with an IC(50 )value of 2.0 6 10(-4 )M.     

Synthesis of newer indolyl/phenothiazinyl substituted 2-oxo/thiobarbituric acid derivatives as potent anticonvulsant agents

2-Amino-5-(heteroarylmethylene)-1,3,4-oxadiazoles/thiadiazoles 7-10 were synthesized by cyclisation of 1-(heteroarylacetyl)semicarbazides/thiosemicarbazides 3-6. 5-(2'-Heteroarylmethylene-5'-aminomethylene-1',3,'4'- oxadiazol-2'-yl/thiadiazol-2'-yl)-2-oxo/thiobarbituric acids 11-18 were synthesized by condensation of compounds 7-10 at the 5th position of 2-oxo/thiobarbituric acids. The newly synthesized compounds showed anticonvulsant activity ranging from 50-90% (seizures protection). Compound 18 (5-(2'-phenothiazinylmethylene-5'-aminomethylene-1',3',4'-thiadiazol-2'- yl)-2-thiobarbituric acid) showed maximum activity being more potent than the reference drug phenytoin sodium (CAS 630-93-3).     

Reactivity of 3-aryl-4-amino-5-mercapto-4H-1,2,4-triazoles: synthesis and biological evaluation of 3,6-diaryl derivatives of 7H-1,2,4-thiazole[3,4-b][1,3,4]thiadiazines, of 3-aryl-4-amino-5-carboxymethylthio-4H-1,2,4-triazoles

Starting from 3-aryl-4-amino-5-mercapto-4H-1,2,4-triazoles (II), two series of 3,6-disubstituted 7H-1,2,4-triazol [3,4-b] [1,3,4] thiadiazines (III) and their 5-carboxymethylthio derivatives (IV) were prepared. From the mercapto-amino-triazoles (II) because of their reactivity in some oxidising media, were obtained the triazole derivatives (V), (VI) and (VII). The synthesis of the alpha-thioketones (VIII) of 3-aryl-5-mercapto-1,3,4-oxadiazoles (I), used in alternative synthesis of triazole-thiadiazines (III), is also reported. All the substances described were subjected to biological screening. In the tests, the carboxymethylthiotriazole (IV) showed weak antiinflammatory activity (carrageenin edema) and more consistent scavanger activity, in vitro, on superoxide anions. The triazole-thiadiazines (III) and triazoles (II), (V) and (VI) showed moderate antimycotic activity.     

3-(4-哌嗪-1-苯基)-6-取代-s-三唑并［3,4-b］［1,3,4］噻二唑盐酸盐的合成及抗菌活性

为了研究水溶性稠杂环化合物的合成方法及抗菌活性，本研究采用3-(4-氯苯基)-6-取代-s-三唑并［3,4-b］［1,3,4］噻二唑(2a～n)在相转移催化剂TBAI作用下与哌嗪发生亲核取代，再与盐酸成盐制备了3-(4-哌嗪-1-苯基)-6-取代-s-三唑［3,4-b］［1,3,4］噻二唑盐酸盐(3a～n)。用试管二倍稀释法研究了新化合物的体外抗菌活性。结果表明，合成的28个新化合物极性碱性哌嗪基的引入可提高化合物的抗菌活性。该类稠杂环化合物的结构有待进一步优化。     

Design and synthesis of novel benzopyran-2-one derivatives of expected antimicrobial activity through DNA gyrase-B inhibition

In an attempt to find a new class of antibacterial agents, we have synthesized thirty new coumarin (2H-benzopyran-2-one) analogues. These derivatives include substituted azetidin-2-ones (beta-lactam) 3a-f, pyrrolidin-2-ones 4a-f, 2H-1,3,4-oxadiazoles 5a-f, and thiazolidin-4-ones 6a-f attached to 4-phenyl-2H-benzopyran-2-one through an oxyacetamido or an oxymethyl bridge. The target compounds were synthesized starting from 2-oxo-4-phenyl-2H-benzo[b]pyran-7-yl-oxyacetic acid hydrazides 2a-f. The new compounds were evaluated as DNA gyrase-B inhibitors through molecular modeling and docking techniques using the Molsoft ICM 3.4-8C program. The synthesized compounds were also screened for antibacterial activity against four different species of Gram-positive and Gram-negative bacteria; as well as screening against C. albicans for antifungal activity. The molecular modeling data were in accordance with the antimicrobial screening results.     

Die Bromierung einiger 2-Anilino-5-aryl-1,3,4-oxadiazole Heterocyclische Verbindungen. 14. Mitt

Bromination of Some 2-Anilino-5-aryl-1,3,4-oxadiazoles 2-Anilino-5-aryl-1,3,4-oxadiazoles were brominated in acetic acid. Only one atom of bromine in para position to the aromatic amino group could be introduced. The acetylated compounds on this N-group resisted bromination. Therefor it was concluded that the 5-phenyl-1,3,4-oxadiazole group has an electron drawing effect. For the single compounds the reaction velocity of bromination was determined.     

Thiourea derivatives of 1,3,4-thiadiazole and their cyclization products]

The synthesis and chemical behaviour of 1-methoxycarbonyl-3-(1,3,4-thiadiazol-2-yl)thyoureas and 7-alkyl-2-methyltio-1,3,4-thiadiazolo [3,2-a]-s-triazine-4-ones is described. All compounds were tested in vitro for their antibacterial activity.