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 and biological evaluation of novel imidazolone derivatives as potential COX-2 inhibitors

Three novel series of 2-(substituted phenyl)-4-(substituted arylidene)-imidazolone-5-(4H)-ones were derived from the corresponding oxazolones by condensation with different arylamines. Eleven of the synthesized compounds were selected and evaluated for their effect on carrageenan-induced rat paw edema. Compound 4b had the same efficacy as the reference standard (indomethacin), and compounds 3b, 3c, 4a, 4d and 9a showed good to excellent activities, with other compounds only weakly active. The potent compounds were evaluated for their inhibitory activities against COX-2-catalyzed PGE(2) production, with 4a, 4b and 3c showing strong inhibitory activity.     

7-chloro-3-(substituted benzylidene/phenyl ethylidene amino)-2-phenylquinazolin-4(3H)-ones: synthesis, antimicrobial and antitubercular evaluation

In this study, a series of 7-chloro-3-(substituted benzylidene/phenyl ethylidene amino)-2-phenyl quinazolin-4(3H)-ones (1–10) were prepared and evaluated for antitubercular activity against Mycobacterium tuberculosis (MTB). The antitubercular screening results indicated that 7-chloro-3-(4-(dimethylamino)benzylidene amino)-2-phenylquinazolin-4(3H)-one (10) was the most potent one (MIC?=?0.78?×?10^?3?μM) and exhibited activity equivalent to the standard compound isoniazid (MIC?=?0.80?×?10^?3?μM). Further, the synthesized compounds were tested for their antibacterial activity against Gram positive and Gram negative bacteria. The comparison of antibacterial and antimycobacterial results indicated that different structural requirements are necessary for a compound to be effective against bacterial and mycobacterial targets.     

Synthesis and antimicrobial activity of coumarin pyrazole pyrimidine 2,4,6(1H,3H,5H)triones and thioxopyrimidine4,6(1H,5H)diones

A series of 5-((3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazol-4-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (4a–f) and dihydro-5-((3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazol-4-yl)methylene)-2-thioxopyrimidine-4,6(1H,5H)-dione (5a–f) derivatives were synthesized by the condensation of 3-(2-oxo2H-chromen-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde (3a–f) with barbituric acid and thiobarbituric acid in acetic acid under microwave irradiation method. The newly synthesized compounds were evaluated for their antibacterial activity against Bcillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeoginosa, and Klebsiella pneumoniae. All the compounds were found to be moderately active against used microorganisms, whereas compounds (4d) and (4e) exhibited good antifungal activity against Aspergillus niger.     

含查尔酮结构N-取代饶丹宁衍生物的合成及抗菌活性研究

目的设计合成两个系列含L-异亮氨酸或L-色氨酸结构的饶丹宁与查尔酮拼合衍生物（4a-4n和5a-5n）,并对其进行体外抗菌活性评价。方法以取代苯乙酮为原料,经缩合反应和Knoevenagel反应得到目标化合物。采用连续稀释法,以诺氟沙星和苯唑西林为阳性对照药,选取7种金黄色葡萄球菌（＆aureusRN4220、＆aureusKCTC503、＆aureusKCTC209、MRSACCARM3167、MRSACCARM3506、QRSACCARM3505、QRSACCARM3519）和大肠杆菌（Ecoli1356）为测试菌株对目标化合物进行体外抗菌活性评价。结果与结论合成了28个未见文献报道的新化合物：（2R）-3-甲基-2-（（Z）-4-氧代-5-（4-（（E）-3-取代苯基-3-氧代丙-1-烯基）苯亚甲基）-2-硫代噻唑烷-2,4-二酮-3-基）戊酸（4a～4n）和（尺）-3-（1H-吲哚-3-基）-2-（（Z）-4-氧代-5-（4-（（E）-3-取代苯基-3-氧代丙-1-烯基）苯亚甲基）-2-硫代噻唑烷-2,4-二酮-3一基）丙酸（5a-5n）。两个系列化合物的结构经1H-NMR和IR谱确证。体外活性测试结果显示,所合成的大部分化合物具有较好的抗菌活性,其中,化合物4n、5g和5j的抗菌活性最好,它们对4种耐药菌的MIC值均为2μg·mL-1。     

Synthesis and biological studies of triazolo-/thiadiazolo-benzoxazines

Diethyl bromomalonate (2) with an equimolar amount of 2-aminophenol (1) in the presence of sodium fluoride undergoes a cyclization reaction to form 2H,4H-2-ethoxycarbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (3). Furthermore, compound 3 undergoes a condensation reaction with hydrazine hydrate in the presence of methanol to yield 2H,4H-2-hydrazinocarbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (4), which on further reaction with aryl isothiocyanates gave 2H,4H-2-[ (4'-substituted)-phenylthiosemicarbazino]-carbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (5). Compound 5 on treatment with NaOH, cone. H2SO4 and diethylmalonate (6). afforded 2H,4H-2-[2'H-3'-thioxo-4'-substituted phenyl-1',2',4'-triazole-5-yl]- 3,4-dihydro-3-oxo-1,4benzoxazine (7). 2H,4H-2-[2'-amino-(substituted)-phenyl-1,3',4'-thiadiazol-5-yl]-3,4-dihydro-3-oxo-1,4-benzoxazine (8) and 2H,4H-2-[5'H-5'-dihydro-2'-thioxo-3'-phenyl-4',6'-dioxo-1,3-diazine]-aminocarbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (9), respectively. The synthesized compounds were investigated for their antibacterial activities against Gram positive as well as Gram negative bacteria with ampicillin trihydrate as standard drug. Structures have been elucidated on the basis of spectral and chemical analyses.     

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 of some oxazolinones and imidazolinones and their antimicrobial screening

A few imidazolinones [1-aminoethyl/phenyl-2-methyl/phe- nyl-4-acetylidene/benzylidene-imidazolin-5[4H]-ones] were newly synthesized from respetive acetylidene/benzylidene oxazolinones. Schiff's bases were synthesized by the reaction between imidazolinones and benzaldehyde. The antimicrobial screening of almost all compounds showed moderate to significant activities against B. subtilis ATCC 6633 and K. pneumoniae ATCC 25063. Compounds 10 [1-aminophenyl-2-phenyl-4-acetylidene-imidazolin-5[4H]-one] and 12 [1-aminophenyl-2-phenyl-4-benzylidene-imi- dazolin-5[4H]-one] showed even better activity than amphotericin B against C. albicans ATCC 29738.     

QSAR modeling of synthesized 3-(1,3-benzothiazol-2-yl) 2-phenyl quinazolin-4(3H)-ones as potent antibacterial agents

Present communication elicits the designing and synthesis of 3-(1,3-benzothiazol-2-yl) 2-phenyl quinazolin-4(3H)-ones as potential antibacterial agents. A number of substituted 2-amino benzothiazoles, 2-amino-5-[(E)-phenyl diazenyl] benzoic acid, and 2-phenyl-4H benzo[d] [1,3] oxazin-4-one were synthesized as the precursor substrates. The compounds were synthesized in excellent yields and the structures were corroborated on the basis of IR, ¹H NMR, Mass, and elemental analysis data. These compounds were screened in vitro for their antibacterial activity against a representative panel of Gram positive and Gram negative bacteria and models were generated through quantitative structure–activity relationship (QSAR).The activity contributions due to structural and substituent effects were determined using sequential regression procedure. The antimicrobial assay data show that the synthesized compounds are found to manifest profound antimicrobial activity.     

Synthesis, antitumor activity and molecular docking study of novel benzofuran-2-yl pyrazole pyrimidine derivatives

A new series of (benzofuran-2-yl)-1-phenyl-1H-pyrazol-4-yl) pyrimidine derivatives were synthesized from 3-(benzofuran-2-yl)-1-phenyl-1H-pyrazol-4-carbaldehyde (1) through different routes of cyclocondensation reactions. Condensation of 1 with active methylene compounds afforded compounds 2-8. The cyclization of 2 with chloroacetic acid, ortho substituted benzoic acid and/or ethanolamine gave compounds 9-12. Also condensation of 2 with hydrazine hydrate followed by cyclocondensation afforded corresponding triazines and pyrazole derivatives 18-27. Some docking studies of the newly prepared compounds as thymidylate synthase inhibitors have been done. Also the cytotoxic activity of some of the prepared compounds as a representative examples was evaluated against HEPG2 (human liver carcinoma cell line) in comparison with 5-fluorouracil (5-Fu).     

Search for potential anticonvulsant drugs: part I. Synthesis of 2-phenyl-3-benzimidazolyl/-alkyl (alkyl-aryl)--quinazolin (3H) -4-one

By the condensation of 2-phenyl-3-carboxy alkyl/aryl-quinazolin (3H)-4-one and substituted (unsubstituted o-phenylenediamine, fifteen new 2-phenyl-3-benzimidazolyl(-alkyl/alkyl-aryl) -quinazolin (3H)-4-ones were prepared. All the fifteen compounds were tested for anticonvulsant activity in mice against pentylenetetrazol. A good protection was obtained by most of the compounds.     

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.     

Synthesis and antimicrobial screening of N-[2-(2/4-substituted phenyl)-1-(5/6 substituted 1H- benzimidazol-2-yl)vinyl]benzamides

A series of (benzamidostyryl)benzimidazole derivatives were synthesized by hydrolyzing 2-phenyl-4-(substituted)benzylidene-5-oxazolones, the azlactone precursors in an acidic medium and treating the product with substituted o-phenylenediamine (OPDA) in situ. The structures of the synthesized compounds were confirmed by spectral and elemental analyses. All synthesized compounds were screened for their in vito antimicrobial activities against some identifiable strains. Thereby, it was found that only nitro substituted benzimidazoles exhibited good to moderate antibacterial activity, while other derivatives were devoid of any antimicrobial effect.     

2,4-二氨基-5-取代苯胺基嘧啶类化合物的合成及抗菌活性

在嘧啶类化合物中,以2,4-二氨基嘧啶类化合物对二氢叶酸还原酶的抑制作用较强。甲氧苄胺嘧啶(TMP)已作为磺胺类药物及某些抗生素的抗菌增效剂广泛用于临床。为了寻找抑酶活性或对细菌选择性抑制作用比TMP更强的化合物,对2,4-二氨基-5-取代苄基嘧啶类的苯环上取代基的改造已做了大量的工作;对这类化合物抑酶活性的构效关系也进行了较多的研究。但对这类化合物中嘧啶环与苯环间的桥键次甲基的改造则报道不多。为了     

Synthesis and antimycobacterial activity of novel 4-[5-(substituted phenyl)-1-phenyl-4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-3-pyrazolyl]-2-methylphenol derivatives

In the present investigation, 4-hydroxy-3-methylacetophenone, on condensation with appropriate aldehydes in methanolic potassium hydroxide solution, yielded the corresponding chalcones (C_I-XI). These corresponding chalcones were reacted with phenyl hydrazide in glacial acetic acid, which led to the formation of novel 4-[5-(substituted phenyl)-1-phenyl-4,5-dihydro-1H-3-pyrazolyl]-2-methylphenol derivatives. All newly synthesized compounds were evaluated for their antimycobacterial activities against isoniazid-resistant Mycobacterium tuberculosis using agar dilution. 4-[5-(4-Fluoro phenyl)-1-phenyl-4,5-dihydro-1H-3-pyrazolyl]-2-methylphenol showed good antimycobacterial activity, with a minimum inhibitory concentration of 0.62 μg/ml.     

Synthesis of curcumin analogues as potential antioxidant, cancer chemopreventive agents

New series of 3, 5-bis(substituted benzylidene)-4-piperidones, 2, 7-bis(substituted benzylidene)cycloheptanones, 1, 5-bis(substituted phenyl)-1, 4-pentadien-3-ones, 1, 7-bis(substituted phenyl)-1, 6-heptadien-3, 5-diones, 1, 1-bis(substituted cinnamoyl)-cyclopentanes, and 1, 1-bis(substituted cinnamoyl)cyclohexanes have been synthesized and tested for their antioxidant activity. Among the tested compounds, compounds II(4), II(9) II(10), II(11), V(1), and V(4) exhibited higher free radical scavenger activity with % inhibition values of 90.71, 91.24, 96.91, 94.26, 99.23, and 99.85%, respectively. Moreover, compound V(1) is the safest member toward peripheral multinuclear neutrophils (PMNs) with a % viability value of 91%. Detailed synthesis, spectroscopic, and biological data are reported.     

Studies on 4(1H)-quinazolinones. 5. Synthesis and antiinflammatory activity of 4(1H)-quinazolinone derivatives

A number of new 4(1H)-quinazolinones were synthesized and evaluated in the carrageenin-induced paw edema test. Most of the compounds were obtained by the cyclization of the appropriately substituted anthranilamides with acid chlorides, followed by further chemical transformation. Structure-activity data suggest that 2-isopropyl-1-phenyl-, 2-cyclopropyl-1-phenyl-, and 1-isopropyl-2-phenyl-4(1H)-quinazolinones afford optimal potency and the presence of a halogen atom is preferred for activity. Adrenalectomy does not affect the antiinflammatory test results. The best result taking into account both efficacy and side effects was displayed by 1-isopropyl-(2-fluorophenyl)-4-(1H)-quinazolinone (50).     

Ring substituted 3-phenyl-1-(2-pyrazinyl)-2-propen-1-ones as potential photosynthesis-inhibiting, antifungal and antimycobacterial agents

Four series of ring substituted (E)-3-phenyl-1-(2-pyrazinyl)-2-propen-1-ones were prepared by means of modified Claisen-Schmidt condensation of acetylpyrazines with aromatic aldehydes. The structures were confirmed by elemental analysis, IR, 1H NMR and 13C NMR spectra. The compounds were tested for specific biological properties and some derivatives exhibited photosynthesis-inhibiting, antifungal and antimycobacterial properties. The most pronounced effects were observed with compounds substituted with phenolic groups. Ortho-hydroxyl substituted derivatives were more potent than the corresponding para-hydroxyl substituted analogues.     

Synthesis of 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carboxamide and related 5'-deoxyimidazole ribonucleosides.

5-Amino-1-(beta-D-ribofuranosyl)imidazole-4-carboxamide (1, AICA ribonucleoside) was converted in two steps to 5-amino-1-(5-deoxy-5-iodo-2,3-O-isopropylidene-beta-D-ribofuranosyl)imidazole-4-carboxamide (3) which was hydrogenated in the presence of Pd/C to yield 5-amino-1-(5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranosyl)imidazole-4-carboxamide (4). The dehydration of 4 yielded 5-amino-1-(5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranosyl)imidazole-4-carbonitrile (7). The compounds 3, 4, and 7 were deblocked with formic acid to furnish 5-amino-1-(5-deoxy-5-iodo-beta-D-ribofuranosyl)imidazole-4-carboxamide (6). 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carboxamide (5), and 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carbonitrile (8), respectively. Compound 8 was acetylated and then deaminated to give 1-(2,3-di-O-acetyl-5-deoxy-beta-D-ribofuranosyl)imidazole-4-carbonitrile (11). The compounds 8 and 11 were converted into 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-thiocarboxamide (9) and 1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-thiocarboxamide (12), respectively. The synthesis of 1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carboxamide (13) was achieved for the first time by the treatment of 11 with hydrogen peroxide in the presence of ammonium hydroxide. The compounds were tested for antibacterial, antifungal, and antiviral activity, with 5 and 6 significantly inhibitory to Staphylococcus aureus.     

Synthesis and biological testing of (5<Emphasis Type="Italic">Z</Emphasis>)-2-aryl-5-arylmethylidene-3,5-dihydro-4<Emphasis Type="Italic">H</Emphasis>-imidazol-4-ones as antimitotic agents

Compounds interacting with cell protein tubulin and microtubules represent an important type of antimitotic agents. A series of tubulin-targeted 2-aryl-4-benzoyl-imidazoles were reported to possess high cytotoxicity, and so, we prepared a series of structural isomers of these to be evaluated as antimitotic agents. The synthesis of the novel (Z)-2-aryl-5-arylmethylidene-3,5-dihydro-4H-imidazol-4-ones involved coupling of substituted hippuric acids with aromatic aldehydes. Subsequent conversion of the resulting oxazolones to the corresponding imidazolones was carried out under microwave irradiation in the presence of urea and ammonium acetate. The cytotoxicity of the majority of the compounds to human epithelial carcinoma cancer cell line A549 was in the sub-micromolar range and was found to be more sensitive to the substituents on the 5-arylmethylidene fragment than on the 2-aryl ring in general. The cytotoxicities of the synthesized compounds were lower than those of the previously reported isomeric 2-aryl-4-benzoyl-imidazoles, and the basic structure–activity relationships in the isomeric pairs were different. Synthesized (5Z)-5-[(4-bromophenyl)methylidene]-2-(4-methylphenyl)-3,5-dihydro-4H-imidazol-4-one, which had the highest cytotoxicity (IC₅₀ ~ 440 nM) in the series of novel compounds, had a definite cytostatic effect on the A549 cells, but its antiproliferative properties were not linked to action on the microtubules. This would be an interesting lead compound for additional investigation into the mechanism of cytostatic action, and further structural optimization.