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.     

Synthesis and biological evaluation of amino acid-linked 1,2,3-bistriazole conjugates as potential antimicrobial agents

A small library of amino acid-linked 1,4-disubstituted 1,2,3-bistriazole conjugates has been synthesized from the N-protected l-amino acids propargyl esters through one-pot click reaction. All the newly synthesized compounds were tested in vitro for antimicrobial activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and fungi (Candida albicans, Aspergillus niger). The antibacterial evaluation data indicated that compounds 3c, 3h, 5a, 5b, 5c, 5d, 5e, 5g, and 5h exhibited comparable activity to standard ciprofloxacin. However, the bistriazoles 3b, 3c, 3e, 3f, and 3g showed good antifungal activity than others against both fungi. Further, docking simulation of the two most active compounds 5c against S. aureus tyrosyl tRNA synthetase and 5h into E. coli topoisomerase II DNA Gyrase B, respectively, was also performed.     

Microwave-assisted synthesis and antimicrobial screening of new imidazole derivatives bearing 4-thiazolidinone nucleus

A new series of compounds 2-((1-(4-(4-arylidene-2-methyl-5-oxo-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazono)thiazolidin-4-ones (4a–o) have been synthesized under conventional and microwave irradiation method. All compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. 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 by bioassays, namely serial broth dilution. The synthesized compounds showed potent antimicrobial activity against tested microorganisms. Compounds 4h, 4j, 4m and 4n were the most potent amongst tested compounds.     

Synthesis, antioxidant, and antibacterial studies of phenolic esters and amides of 2-(1-benzofuran-2-yl) quinoline-4-carboxylic acid

A new series of phenolic esters 2(a–j) and amides 3(a–c) of 2-(1-benzofuran-2-yl) quinoline-4-carboxylic acid were synthesized by the reaction of 2-(1-benzofuran-2-yl)-quinoline-4-carboxylic acid (1) with various substituted phenols and secondary amines using ethyl-(N′,N′-dimethylamino)propyl carbodiimide hydrochloride (EDC.HCl) as a coupling agent. The newly synthesized compounds were evaluated for in vitro antioxidant and antibacterial activity. Among all tested compounds 2a, 2c, 2e, and 2h showed good chelating ability with Fe⁺² ions, whereas compounds 2g and 2j exhibited good scavenging activity with DPPH free radicals. Concerning antibacterial activities compounds 2a, 2b, 2c, and 2h were found to be equipotent to ampicillin against Enterococcus sp and Staphylococcus aureus, while compound 2e is found to be as potent as ampicillin against Pantoea Dispersa and Ochrobactrum sp. amide derivatives 3(a–c) were found to be less potent when compared to standard.     

Synthesis,antimicrobial, and cytotoxic activities of novel benzimidazole derivatives bearing cyanopyridine and 4-thiazolidinone motifs

A series of 6-(1H-benzo[d]imidazol-2-yl)-2-(2-(3-nitrophenyl)-4-oxothiazolidin-yl)-4-(aryl)nicotinonitriles 5a–l were synthesized and characterized by IR, ¹H NMR, ¹³C NMR, and mass spectrometry techniques. These novel compounds 5a–l were screened for their in vitro antimicrobial activity against different bacterial and fungal strains and in vitro cytotoxicity study (HeLa cell line) using MTT colorimetric assay. The results demonstrated that compounds 5c, 5e, and 5i–k exhibited excellent antibacterial activity, while compounds 5d, 5i, and 5k were found to be the most potent antifungal agents. From the standpoint of SAR studies, it was observed that the presence of electron donating groups remarkably enhanced the antimicrobial activity of newly synthesized compounds. Further, the results of preliminary MTT cytotoxicity studies on HeLa cells suggested that potent antimicrobial activity of 5c–e and 5i–k was accompanied by low cytotoxicity.     

Synthesis and characterization of novel benzimidazole bearing pyrazoline derivatives as potential antimicrobial agents

A new series of compounds N-(4-(2-(3-(1H-benzo[d]imidazol-2-yl)-5-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethoxy)phenyl)acetamides (5a–u) were synthesized and structures of these compounds were elucidated by spectral (IR, ¹H NMR, ¹³C NMR, and mass spectra) analysis. Antimicrobial activity was measured against Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688), Staphylococcus aureus (MTCC 96), Streptococcus pyogenes (MTCC 442), Candida albicans (MTCC 227), Aspergillus niger (MTCC 282), and Aspergillus clavatus (MTCC 1323) by serial broth dilution method. Evaluation of antimicrobial activity revealed that compounds 5f, 5i, 5q, and 5t were the most active antibacterial, while compounds 5e, 5g, 5h, 5j, 5p, 5r, and 5u were the most potent antifungal agents as compared to standard drugs and thus could be promising new lead molecules.     

Synthesis and characterization of flurbiprofen hydrazide derivatives as potential anti-HCV, anticancer and antimicrobial agents

A novel series of new flurbiprofen hydrazide derivatives 2-(2-fluorobiphenyl-4-yl)-N′-[(substituted phenyl/5-nitro-2-furyl)methylene]propanehydrazide (3a–k), 2-(2-fluorobiphenyl-4-yl)-N-(2-substituted-4-oxo-1,3-thiazolidine-3-yl)propanamide (4a–b, 4d–k), 2-[2-(2-fluorobiphenyl-4-yl) propanoyl]-N-substituted hydrazinecarbothioamide (5a–h) and 2-(2-fluorobiphenyl-4-yl)-N′-[(3-methyl-4-oxo-1,3-thiazolidin-2-ylidene]propanehydrazide (6a–b, 6e and 6g) has been synthesized in this study. All synthesized compounds were screened for antimicrobial activity against various bacterial and fungal strains. Additionally, compounds were evaluated for the ability to inhibit Hepatitis C virus NS5B polymerase. The most active 4-thiazolidinone compound was 4k (SGK119) with 67.0 % and thiosemicarbazide compound was 5d (SGK123) with 69.50 % inhibition at 200 μM against hepatitis C virus NS5B RNA polymerase. Anticancer activity of the selected compounds (3i, 3j, 3h, 4d, 4i and 6b) was determined at a single dose towards the full panel of 60 human cancer cell lines by the National Cancer Institute (NCI). 2-(2-Fluoro-4-biphenylyl)-N-[2-[4-(trifluoromethyl)phenyl]-4-oxo-1,3-thiazolidine-3-yl]propanamide 4d, containing thiazolidinone ring, demonstrated the most marked effect with 20.80 % growth percent on leukaemia cancer cell line SR at 10^?5 M. The results demonstrated that none of the compounds tested have anticandidal and antifungal activities, but two of them (4a and 4i) showed antibacterial inhibition against Micrococcus luteus, and Staphylococcus cohnii and Staphylococcus aureus, respectively.     

Synthesis and antimicrobial screening of 4-thiazolidinone and 2-azetidinone derivatives of piperazine

The Schiff’s bases 3a–3h were synthesized by reacting substituted/unsubstituted aromatic aldehydes 2a–2h with 1-(2-aminoethyl)-piperazine 1. A series of novel aryl-3-(2-piperazin-1-ylethyl)-1,3-thiazolidin-4-one 4a–4h and 3-chloro-1-{2-[4-(chloroacetyl)piperazin-1-yl]ethyl}-4-arylazetidin-2-one 5a–5h were synthesized from the Schiff’s bases of 1-(2-aminoethyl)-piperazine 3a–3h. The structures of synthesized compounds were confirmed by analytical (C, H, and N) and spectral (FT-IR, ¹H NMR, ¹³C NMR, and Mass) data. The compounds 4a–4h and 5a–5h were screened for antimicrobial activity. The compounds 4a, 4d, 4f, 4g, 5a, 5d, 5f, and 5g exhibited substantially significant antibacterial as well as antifungal activity.     

Synthesis of some novel C-5 and N-3 substituted 2-(2-hydroxyphenylimino)thiazolidin-4-one derivatives with broad-spectrum antimicrobial activity

In the present article, compounds 5-((substituted-2-chloroquinolin-3-yl)methylene)-2-(2-hydroxyphenylimino)thiazolidin-4-ones (3a–k), 1-(2-(2-(2-hydroxyphenylimino)-4-oxothiazolidin-3-yl)-2-oxoethyl)pyrimidine-2,4,6(1H,3H,5H)-trione (6) and 1-(2-(5-((substituted-2-chloroquinolin-3-yl)methylene)-2-(2-hydroxyphenylimino)-4-oxothiazolidin-3-yl)-2-oxoethyl)pyrimidine-2,4,6(1H,3H,5H)-triones (8a–k) have been synthesized by substituting C-5 and N-3 position of parent compound 2-(2-hydroxyphenylimino)thiazolidin-4-one (1). Structures of the newly synthesized compounds were assigned on the basis of elemental analyses, IR, ¹H NMR, ¹³C NMR, and mass spectra. In vitro antimicrobial activity of target compounds (3a–k, 6 and 8a–k) was investigated against two Gram-positive, two Gram-negative bacteria and three fungal strains. Among the tested compounds (3e), (3f), and (3h) showed very good antifungal activity, while compound (6) showed very good antibacterial activity. Compounds (8e), (8f), and (8h) showed excellent antifungal and antibacterial activities.     

Synthesis and antitubercular activity of novel pyrazole–quinazolinone hybrid analogs

A series of 2-(substituted-phenyl)-3-(((3-(pyridin-4-yl)-1-(p-tolyl)-1H-pyrazol-4-yl)methylene)amino)-quinazolin-4(3H)-ones have been synthesized. The structures of the synthesized compounds were assigned on the basis of IR, ¹H NMR, ¹³C NMR, and mass spectral data, while their abilities to inhibit growth of Mycobacterium tuberculosis in vitro have been determined. The results show that compounds 5a, 5c, 5d, 5g, and 5k exhibited excellent antitubercular activity with percentage inhibition of 96, 90, 94, 93, and 92, respectively at a minimum inhibitory concentration (MIC) of <6.25 μg/mL, whereas compounds 5b, 5e, 5f, 5h, 5i, 5j, and 5l exhibited moderate- to- good antitubercular activity with percentage inhibition of 68, 70, 67, 64, 59, 73, and 67, respectively, at a MIC of >6.25 μg/mL. From the secondary screening, the actual MIC of compounds 5a, 5c, 5d, 5g, and 5k are <3.125.     

Synthesis,antimicrobial, and antioxidant activity of benzofuran barbitone and benzofuran thiobarbitone derivatives

The synthesis of novel series of benzofuran derivatives, containing barbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl) methylidene]pyrimidin-2,4,6(1H,3H,5H)-trione (4a–i) and thiobarbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl)methylidene]-2-thioxodihydropyrimidin-4,6(1H, 5H)-dione (5a–i) have been reported. The target compounds (4a–i) and (5a–i) were synthesized by the Knoevenagel condensation of (5-substituted-1-benzofuran-2-yl)(2/4-substitutedphenyl) methanone (3a–i) with barbituric acid and thiobarbituric acid, respectively, in acid medium. These compounds were screened for the antimicrobial and antioxidant activities. From antimicrobial activity results it was found that compounds 4a, 5a, 4c, and 5c displayed good antibacterial and antifungal activity against all tested strains. Further, the synthesized compounds were studied for docking on the enzyme, Glucosamine-6-phosphate synthase and the compounds 4c and 5c have emerged has an active antimicrobial agent with least binding energy (?5.27 and ?4.85 kJ mol^?1). Compounds 4e, 4f, 5e, and 5f showed promising free radical scavenging activity and compounds 5a and 5b showed good chelating ability with Fe²⁺ ions.     

Synthesis of some new indolo[2,3-c]isoquinolinyl pyrazoles, -1,3,4-oxadiazoles and their biological activities

A new series of novel compounds [10-substituted 6H, 7H-indolo[2,3-c]isoquinolin-5-one-6-yl]carbohydrazides (3a–c), 1-[10-substituted 6H, 7H-indolo[2,3-c]isoquinolin-5-one-6-yl]fomyl-, -3′,5′-dimethylpyrazoles (4a–c), -3′,5′-diphenylpyrazoles (5a–c), -3′-methylpyrazol-5′-ones (6a–c) and -1′,3′,4′-oxidiazole-2′-thiones (7a–c) linked to indoloisoquinoline at position-6 through formyl bridge was prepared. The structures of these newly synthesized compounds were confirmed by their spectral studies and elemental analysis. These compounds have been screened for their antimicrobial and antioxidant activities. Compounds 4a, 4b, 5a, 5b, 5c, 6b, 7a, and 7c exhibited the maximum zone of inhibition against A. niger, A. flavus, and A. fumigatus. Compounds 4a, 5a, 5c, 6b, 6c, 7a, and 7b showed good antibacterial activity. Compounds 4b, 4c, 5b, 5c, 6a, 6b, 7a, 7b, and 7c showed good radical scavenging activity compared with standards.     

Synthesis and biological evaluation of novel condensed pyrimidinylmethylsulfinylbenzimidazoles as antiulcer agent

Current therapies to treat gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), and other acid-related diseases either prevent stimulation of the parietal cell (H₂-receptor antagonists) or inhibit gastric H⁺/K⁺-ATPase (proton pump inhibitors). The inhibition of acid production by proton pump inhibitors (PPI’s) provides more effective relief of symptoms and healing. A series of novel 4-substituted-2-(1H-benzimidazol-2-yl)methylsulfinylpyrimidines were synthesized as target compounds and antiulcer activity was done using parameters like total acidity, pH, and total gastric acid volume by pylorus ligation method on Wistar rats. Three different dose levels were employed for testings. The target compounds 4-substituted-2-(1H-benzimidazol-2-yl)methylsulfinylpyrimidines were effective for ulcer treatment and among them compounds 10c, 10d, 8b, and 8c exhibited potent antisecretory activity. Overall, compounds 10c, 10d, 8b, and 8c can be looked upon as potential leads for further development and investigations.     

Synthesis, characterization and antimicrobial screening of hybrid molecules containing benzimidazole-pyrazole and pyridine nucleus

The rising prevalence of multi-drug resistant Gram-positive, Gram-negative bacteria and fungi continues to provide momentum for search and development of novel active antimicrobial agents against these pathogens. In continuation to this, the present article deals with the synthesis and antimicrobial activity of a novel series of (3-(1H-benzo[d]imidazol-2-yl)-5-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)(pyridin-4-yl)methanones 4a–n, synthesized by the reaction of benzimidazolyl chalcones with isoniazide 3. The structures of synthesized compounds were elucidated on the basis of IR, NMR, and mass spectra. The newly synthesized compounds 4a–n were screened for their antimicrobial activity against different strains of bacteria and fungi using serial broth dilution method. Compounds 4d, 4f, 4h, and 4g were found to be most active with MIC of 25?μg/mL against selected bacterial strains. Compounds 4c, 4g, and 4n were found to be most active with MIC of 100?μg/mL against selected fungal strains.     

Synthesis of promising antimicrobial agents: a novel series of N-(4-(2,6-dichloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides

A series of novel compounds N-(4-(2,6-dichloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (5a–l) were synthesized by a series of multistep reactions. Newly synthesized compounds have been characterized by IR, ¹H NMR, ¹³C NMR, and mass spectral data. Antimicrobial screening of title compounds 5a–l was examined against Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and three fungi (Candida albicans, Aspergillus niger, and Aspergillus clavatus) by serial broth dilution method. Synthesized compounds showed potent inhibitory action against test organisms. Screened compounds 5e–g and 5i–l were associated with considerably higher antibacterial and antifungal activities than commercially used antibiotics.     

Synthesis and biological evaluation of novel 4,5-dihydropyrazole derivatives as potent anticancer and antimicrobial agents

A focused library of 4,5-dihydropyrazole dervivatives (4, 5, 6, 7a–h, 8, 9a–g, and 10a–g) were synthesized from novel 5-(2,6-difluorophenyl)-3-phenyl-4,5-dihydropyrazole-1-carbothioamide 4. The synthesized compounds were characterized using elemental analysis and spectral data (IR, mass spectra, ¹H and ¹³C NMR) and evaluated for antimicrobial activity by broth dilution method and in vitro anticancer activity. Among the synthesized compounds 7a, 9c, 9g, and 10d exhibit broad spectrum antimicrobial activity against tested microbial strains. The in vitro cancer results ascertain 7a, 9c, and 10d are most potent molecules in comparison to reference standard cisplatin.     

Antibacterial and free radical scavenging potential of synthesized 7-hydroxy-2-aryl-6-aryldiazenyl-4H-chromen-4-ones

A series of 7-hydroxy-2-aryl-6-aryldiazenyl-4H-chromen-4-one derivatives (6a–m) was synthesized in quantitative yields and their structures were corroborated on the basis of FT-IR, ¹H, ¹³C NMR, ESI–MS, and elemental analysis data. The synthesized compounds were screened for in vitro antibacterial activities against a representative panel of Gram-positive and Gram-negative bacteria, as well as to evaluate their antioxidant potential using DPPH assay method. Bio-evaluation studies revealed that compounds 6c, 6d, 6e, 6j, and 6l exhibited moderate to good antibacterial activity against all the tested bacterial strains. Furthermore, from the antioxidant screening results, it has been observed that compounds 6c, 6e, and 6g manifested profound antioxidant potential (IC₅₀ <7.68 μM) in comparison to the standard antioxidant ascorbic acid.     

Synthesis and characterization of novel benzo[d][1,3]dioxole gathered pyrazole derivatives and their antimicrobial evaluation

Benzo[d][1,3]dioxole gathered pyrazole derivatives (4a–i) were synthesized by the reaction of chalcones with phenyl hydrazine in presence of absolute alcohol as a solvent. Chalcones were prepared by the Claisen-Schmidt reaction between 1-(benzo[d][1,3]dioxol-5-yl)ethanone (2) and substituted aromatic aldehydes. The synthesized compounds were characterized by spectral and elemental analysis data. Furthermore, Benzo[d][1,3]dioxole gathered pyrazole derivatives (4a–i) were evaluated for their in vitro antimicrobial activity. Among the newly synthesized compounds 4a, 4c, 4 g and 4 h showed the excellent antifungal activity and as well as 4a and 4d showed the excellent antibacterial activity when compared to other compounds.     

Synthesis of β-amino carbonyl derivatives of coumarin and benzofuran and evaluation of their biological activity

A series of β-amino carbonyl compounds containing coumarin (4a–h) and benzofuran (6a–i) moieties was synthesized by a three component Mannich reaction of 3-acetyl-2H-chromen-2-one (1) or 1-(1-benzofuran-2-yl) ethanone (5) with p-substituted aromatic aldehydes (2a–g) and aromatic amines (3a–b) in the presence of cerric ammonium nitrate as a catalyst. The newly synthesized compounds were screened for antimicrobial and antioxidant activities. Compounds 4b, 4e, 4f, 6f, 6g, and 6i showed microbial inhibition with minimal inhibition concentration ranging between 0.040 and 0.500 mg/mL, compounds 4b, 4c, 6c, 6e, and 6i showed promising free radical scavenging activity and compounds 4b, 4f, 6c, 6d, and 6h showed good chelating ability with Fe²⁺ ions. The synthesized compounds were studied for docking on the enzyme, glucosamine-6-phosphate synthase to predict the binding affinity and orientation at the active site of the receptor.     

Synthesis, characterization, and biological evaluation of novel thiazole and pyrazole derivatives of quinoline-4-carboxylic acid as potential antimicrobial agents

A series of quinoline-based heterocycles prepared and bioevaluated for their possible antimicrobial activity against a panel of gram-positive bacteria [Staphylococcus aureus (ATCC-9144) and Bacillus subtilis (ATCC-6633)] and gram-negative bacteria [Pseudomonas aeruginosa (ATCC-25615), and Escherichia coli (MTCC-739)], and fungal strains [Candida albicans (ATCC-24433), Aspergillus niger (MTCC-872), and Aspergillus fumigatus (MTCC-343)] by the known methods. All the prepared quinoline derivatives have shown significant antimicrobial activities. Few compounds, viz. 4b, 4c and 4a, 4c proved to be active at low concentrations against Sa and Ca, respectively, while compounds 4a, 6d, and 6b showed milder inhibitory effects against other microbes. The structures of newly synthesized compounds were characterized by elemental analysis, Infrared (IR), ¹HNMR, ¹³C-NMR and Mass-spectroscopy.