Synthesis, antimicrobial and antioxidant activities of some new indole derivatives containing pyridopyrimidine and pyrazolopyridine moieties

New indole analogues containing pyrido[2,3-d]pyrimidin-4-(3H)-ones (3a–i), pyrazolo[3,4-b]pyridin-3-amines (4a–i) and pyrido[2,3-d]pyrimidin-4-amines (5a–i) were synthesized using appropriate synthetic routes. These newly synthesized compounds were screened for their antimicrobial and antioxidant activities. Compounds 3a, 3g, 4c, 4h, 4i, 5a, 5c and 5f exhibited good antibacterial and antifungal activities. The compounds 3b, 3c, 3g, 4a, 4h, 4i and 5a exhibited good radical scavenging activity. Compounds 3a and 4d exhibited good metal chelating activity compare with standards.     

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, physicochemical properties, antimicrobial and antioxidant studies of pyrazoline derivatives bearing a pyridyl moiety

A series of new pyrazoline compounds bearing a pyridyl moiety (4a–i) were synthesized by condensing appropriate chalcones with hydrazine hydrate and tested for antimicrobial and antioxidant activities. According to in vitro antimicrobial activity against Bacillus subtilis, Staphylococcus epidermidis, Proteus vulgaris, Pseudomonas aeruginosa, Aspergillus niger and Penicillium chrysogenum and antioxidant activity by DPPH method, the compounds 4a, 4d, 4i and 4e, 4f, 4h showed maximum antimicrobial and antioxidant activities, respectively. Physiochemical properties and Lipinski’s ‘Rule of Five’ analysis predicted higher intrinsic quality of the synthesized compounds and revealed that these compounds have good bioavailability and druglikeness properties.     

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.     

In-vitro cytotoxicity,antioxidant, bleomycin-dependent DNA damage and immunomodulatory evaluation of 1-(4-acetylphenyl)-3-aryloxypyrrolidine-2, 5-dione based derivatives

A one pot, economical, and efficient synthesis of 1-(4-acetylphenyl)-3-aryloxypyrrolidine-2,5-diones-based derivatives 5a-l have been accomplished in single steps and in satisfactory yields from 1-(4-acetylphenyl)-pyrrole-2,5-diones 3 and phenols 4a–l. All the compounds were characterized by physical, spectroscopic, and elemental analysis. The selection of the bioassays was based on proving the drug receptor binding concept. Compounds 5g, 5k, 5h, 5i, 5a, and 5f showed the highest inhibitory antioxidant activity using ABTS methods. Compounds 5k, 5g, 5c, 5h, 5b, 5d, 5f, and 5j manifested the best protective effect against DNA damage induced by bleomycin. Moreover, an in-vitro cytotoxic activity evaluation of all synthesized compounds was against four cancer cell lines using 5-Fluorouracil as a standard anticancer drug.     

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, antitumor activity of 2-amino-4H-benzo[h]chromene derivatives, and structure–activity relationships of the 3- and 4-positions

Several 2-amino-4H-benzo[h]chromenes (3a–i) and (5a–h) were obtained by reaction of 4-chloro-1-naphthol (1) with α-cyanocinnamonitrile (2a–i) or ethyl α-cyanocinnamate derivatives (4a–h), respectively. Structures of these compounds were established on the basis of spectral data. The antitumor activity of the synthesized compounds was investigated in comparison with Vinblastine, Colchicine, and Doxorubicin well-known anticancer drugs, using MTT colorimetric assay. Among them, the compounds 5e, 3c, 5f, b, d, 3d, 5c, a were the most active against MCF-7, 5a against HCT-116 and 5a, 3e, a against HepG-2 as compared with the standard drug Vinblastine, while the compounds 5e, 3c, 5f, b, d, 3d, 5c, a, h, 3i, g, a, e were the most active against MCF-7, 5a, c, e, f, b, 3e, c, g, b, 5d, h, 3d, i, 5g against HCT-116, 5a, 3e, a, 5e, 3c, 5d, c, f, 3b, 5g, 3g, 5h against HepG-2 as compared with the standard drug Colchicine. The structure–activity relationships of the 3- and 4-positions were discussed.     

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 new oxadiazole derivatives as anti-inflammatory, analgesic, and antimicrobial agents

In search of pharmalogically active molecules in the class of oxadiazoles, the present article deals with the synthesis of 5-(5′-fluoro-2′-methoxybiphenyl-3-yl)-1,3,4-oxadiazol-2(3H)-one 2 from its hydrazide analog 1. The compound 2 was regioselectively N-alkylated with alkyl halides and produced the compounds 3a–f. Compound 3f was further functionalized with substituted benzenesulfonyl chlorides to give compounds 3g–j. The synthesized compounds were characterized by elemental and spectral analysis. Newly synthesized compounds were tested for their in vivo anti-inflammatory, analgesic, and in vitro antimicrobial activities. The compounds 3a–c were found to have promising anti-inflammatory and analgesic activities. Compounds 3b, 3f, and 3g showed significant antibacterial and antifungal activities.     

Synthesis and antimicrobial activity of 5-chloroindoline-2,3-dione derivatives

A series of 3-(5-chloro-2-oxoindolin-3-ylideneamino)-2-arylthiazolidin-4-ones 4a–k and 5-chloro-3-(3-chloro-2-oxo-4-arylazetidin-1-ylimino)indolin-2-ones 5a–k was synthesized. The structures of final compounds were confirmed by analytical (C, H, N) and spectral (FT-IR, ¹H NMR, ¹³C NMR and Mass) data. The synthesized compounds were screened for possible antibacterial and antifungal activity. Compounds 4c, 4f, 4g, 4h, 4i, 4j, 5c, 5f, 5g, 5h, 5i and 5j showed substantially significant activity.     

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.     

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.     

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 antioxidant activities of 2-[1-{3,5-diaryl-4,5-dihydro-1H-pyrazolenyl}]-4-(4-nitrophenyl)-[1,3]-thiazoles

In this study, various substituted chalcones, prepared by condensing substituted acetophenones with substituted aldehydes/arylfurfurals, were treated with thiosemicarbazide in basic media to produce 1-thiocarbonyl-3,5-disubstituted pyrazolines which on further reaction with substituted phenacyl bromides afforded the title compounds in good yield. Structures of the newly synthesized compounds were assigned on the basis of elemental analyses, IR, ¹H NMR, and mass spectral studies. The newly synthesized compounds were tested for their in vitro antibacterial and antifungal activities against a variety of microorganisms and antioxidant activities by diphenylpicrylhydrazyl radical scavenging assay. Among the derivatives, compounds 3b, 3e, 6a, and 6h were identified as potent antioxidants. Compounds 3d, 3e, and 6a–f have emerged as the most promising antimicrobial agents displaying the maximum activity against all the tested microorganisms.     

Synthesis of 1-(4-aminosulfonylphenyl)-3,5-diarylpyrazoline derivatives as potent antiinflammatory and antimicrobial agents

A new series of 1-(4-aminosulfonylphenyl)-3,5-diaryl pyrazolines (5) was synthesized by the reaction of appropriate chalcones 3 with 4-hydrazinobenzenesulfonamide hydrochloride (4) in ethanol in the presence of catalytic amount of acetic acid. All newly synthesized compounds were in vivo evaluated for their antiinflammatory activity using carrageenan-induced rat paw edema assay. Five of the newly synthesized compounds, 5d, 5g, 5h, 5i, and 5m displayed significant antiinflammatory activity, greater than 55% inhibition 3?h after the carrageenan injection. All the newly synthesized compounds were evaluated for their in vitro antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis); two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and two yeast (Candida albicans and Saccharomyces cerevisiae). Some of the newly synthesized compounds 5a, 5f, 5g, 5h, 5j, and 5k showed excellent antifungal activity, greater than the reference drug amphotericin B, against Saccharomyces cerevisiae.     

Synthesis and antimicrobial activity of bischalcone derivatives

Several bischalcones (2a–h and 5a–e) and flavones (3a–f) were synthesized and evaluated for their antimicrobial actions. Bischalcones were prepared by condensing 1,1′-(4,6-dimethyl-1,3-phenylene)diethanone (1) or 1-(5-acetyl-2,4-dimethoxyphenyl)-1-ethanone (4) with arylaldehydes. Bischalcones were cyclized in presence of iodine to give corresponding flavones (3a–f). An alternative route to synthesize the flavones consisted in preparing the diester derivatives (6a–f) of (1) with different aromatic acids, which could be converted to β-diketones followed by cyclization to give the corresponding flavones. However, all the attempts in this direction were unsuccessful and it could not be possible to proceed beyond diester stage; six diester derivatives (6a–f) were synthesized. The structures of the synthesized compounds were assigned on the basis of ¹H NMR, mass spectral data and microanalyses results. The antimicrobial screening was performed at a concentration of 100 μg/mL by cup plate method; the compounds inhibiting growth of one or more of the microorganisms were further tested for their minimum inhibitory concentration (MIC) by turbidity method. Preliminary antimicrobial results revealed that the compounds 2a–h and 3a–f were significant in their antibacterial and antifungal activities. MICs results showed that the compound 2f exhibited very good activity against E. coli, P. aeruginosa, and C. albicans with MIC-12.5 μg/mL. Similar type of activity was shown the compound 3a against S. aureus and C. albicans with MIC-12.5 μg/mL. Another compound, 3f, was active against P. aeruginosa and C. albicans with MIC-12.5 μg/mL. Methylation of the two chelated hydroxyls (5a–e) significantly reduced the activity. However, oxidative cyclization of bischalcones resulted in compounds (3a–f) which were found to be considerably active. Diesters (6a–f) were insignificant in their antimicrobial activities.     

Synthesis, characterization, and antimicrobial evaluation of novel naphthalene-based 1,2,4-triazoles

In order to search for new bioactive molecules with significant antimicrobial action, a series of 1,2,4-triazole and naphthalene analogs bearing structurally diverse substituents, N-(3-mercapto-5-(naphthalen-1-yl)-4H-1,2,4-triazol-4-yl)(aryl)amides 3a–l were synthesized in good yield by a multi-step synthetic procedure. Their antimicrobial activity was screened against various Gram-positive and Gram-negative bacteria and fungi. Compounds 3a, 3f, 3g, 3j, and 3k exerted strong inhibition of the investigated bacterial and fungal strains compared to control antibiotic ampicillin and antifungal griseofulvin. On the basis of statistical analysis, it is observed that the compounds give significant co-relation. All the synthesized compounds have been characterized by IR, ¹H NMR, ¹³C NMR, and mass spectral data.     

Synthesis, antimicrobial, and antioxidant activities of some new indole analogues containing pyrimidine and fused pyrimidine systems

To examine new leads with potential antimicrobial and antioxidant activities, a new series of tetrahydropyrimidines (2a–c, 3a–c and 4a–c), pyrazolo[3,4-d]pyrimidines (5a–c), and ditetrazolo[1,5-a;1′,5′-c]pyrimidines (6a–c) were synthesized in this study using appropriate synthetic routes. The newly synthesized compounds have been tested for their antimicrobial and antioxidant activities against DPPH stable free radical. In the case of antibacterial activity, compounds 2a, 6a, and 6c exhibited the maximum zone of inhibition against Staphylococcus aureus; compound 6c exhibited maximum zone of inhibition against Pseudomonas aeruginosa; and compound 2a showed maximum inhibitory growth against Klebsiella pneumonia. While in the case of antifungal activities, compound 5a showed good zone of inhibition against Aspergillus oryzae, compounds 2b and 6a exhibited maximum zone of inhibition against Aspergillus niger. In case of antioxidant activities, compound 2a showed the highest DPPH radical scavenging activity.     

An efficient, solvent-free microwave-assisted synthesis and antimicrobial screening of 1,6-dihydropyrimidine analogues

A series of compounds 4-(4-(4-aminophenyl)-6-(aryl)-1,6-dihydropyrimidin-2-ylthio)butanenitriles 5a–l were synthesised by the reaction of allyl cyanide 4 with 3a–l. Compounds 3a–l were prepared from reaction between various chalcones 1a–l and thiourea in presence of catalytic amount of potassium hydroxide. Compounds 3a–l, and 5a–l were prepared by classical as well as MWI methods. Structures of the compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral data. The newly synthesized compounds 5a–l were screened for their antimicrobial activity against different strains of bacteria and fungi using serial broth dilution method. Compounds 5e, 5g and 5k were found to be most active with MIC of 25?μg/mL against selected bacterial strains, while compound 5d, 5f, 5j and 5k were found to be most active with MIC 50?μg/mL against selected fungal strains.     

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.