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,antimicrobial and cytotoxic activity of 2-azetidinone derivatives of pyridyl benzimidazoles

In the present study, a series of novel 6-(1H-benzo[d]imidazol-2-yl)-2-(3-chloro-2-oxo-4-phenylazetidin-1-yl)-4-(aryl)nicotinonitriles 6a–o were efficiently synthesized and evaluated for their in vitro antibacterial activity against Gram-positive (Staphylococcus aureus and Streptococcus pyogenes), Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and fungal (Candida albicans, Aspergillus niger and Aspergillus clavatus) strains. The results of antimicrobial study revealed that compounds 6b, 6c, 6d, 6h and 6i exhibited substantial antibacterial activity while compounds 6c and 6h emerged as the most potent antifungal agents compared to the standard drugs chloramphenicol and ketoconazole, respectively. From the standpoint of SAR studies, it was observed that the presence of electron-withdrawing groups remarkably enhances the antibacterial activity of newly synthesized compounds. Further, the results of preliminary MTT cytotoxicity studies on HeLa cells suggested that potent antimicrobial activity of 6b, 6c, 6d, 6h and 6i is accompanied by low level of cytotoxic concentrations. All the newly synthesized analogues were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral data.     

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.     

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.     

Anti-mycobacterial, cytotoxic activities of Knoevenagel and (E)-α,β-unsaturated esters and ketones from 2-chloronicotinaldehydes

Series of 2-chloronicotinaldehyde Knoevenagel derivatives 3a–r; (E)-α,β-unsaturated esters and ketones 5a–k were prepared and evaluated for their in vitro anti-mycobacterial activity against Mycobacterium tuberculosis H₃₇Rv (Mtb). Compounds 3e, 5b, 5d, 5e, 5g and 5i–k were shown potent to significant activity. Compound 5j is the most potent Mtb inhibitor (MIC: 4.89 μM) when compared to standard drugs Ethambutol (MIC: 7.63 μM) and Ciprofloxacin (MIC: 9.44 μM). Eight compounds displayed potent/significant activity against M. tuberculosis were chosen for the cytotoxicity against three cell lines (Raw 264.7, MCF7, and HeLa). Compound 5j displayed low toxicity with high selective index (15–30) and is an interesting new compound may serve for the development of therapeutics targeted against anti-mycobacterial compounds. This is the first report assigning in vitro anti-mycobacterial inhibitory activity and structure–activity relationship for this class of substituted 2-chloronicotinaldehyde derivatives and presents new family of compounds.     

Synthesis, in vitro cytotoxicity, and antibacterial studies of new asymmetric bis-1,2,4-triazoles

A series of asymmetric bis-1,2,4-triazoles (4a–l) were synthesized from respective 1,2,4-triazole-3-thiocarbohydrazides (2a, b) via base catalyzed dehydrative cyclization of thiosemicarbazide intermediates (3a–l). The synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, and Mass spectral studies. The asymmetric bis-1,2,4-triazole derivatives (4a–l) were evaluated for in vitro antioxidant activity by DPPH radical scavenging assay method. The compounds with significant antioxidant potential were evaluated for in vitro cytotoxicity by MTT assay method against HT29 (Human adenocarcinoma) and MDA-231 (Human breast cancer) cancer cell lines. All the synthesized compounds were evaluated for in vitro antibacterial activity against Bacillus subtilus (ATCC 6633), Staphylococcus aureus (ATCC-25923), Escherichia coli (ATCC-25922), and Pseudomonas aeruginosa (ATCC-27853).     

Synthesis and evaluation of analgesic, anti-inflammatory, and anticancer activities of new pyrazole-3(5)-carboxylic acid derivatives

In this article, we synthesized a series of novel 1-benzyl-5(3)-p-tolyl-1H-pyrazole-3(5)-carboxylic acid derivatives and characterized by IR, ¹H NMR, and mass spectroscopy. Compounds were evaluated for their in vivo analgesic and anti-inflammatory activity using the p-benzoquinone-induced writhing test and the carrageenan-induced paw edema model, respectively. Out of 14 compounds tested, 7a, 7c, 7e, 7f, 7i, 8a–b, and 8f–g exhibited potent analgesic and/or anti-inflammatory activity as compared to reference drugs aspirin and indomethacin. Anticancer activity of these compounds was assessed against five cancer cell lines with the MTT assay (HL-60, human promyelocytic leukemia cells; HeLa, human cervical cancer cells; Raji, human B lymphocyte cell line; MCF7, human breast adenocarcinoma cell line; MDA-MB-231, estrogen-independent human breast cancer cell line). Compounds 7a, 8a, and 8b with high anti-inflammatory activity, and also 7d and 7j with mild anti-inflammatory activity exhibited promising anticancer activity against some selected cell lines.     

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.     

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 and biological evaluation of novel benzoquinones as potential antimicrobial agents

New series of 2,5-dihydroxyphenyl-1,3-thiazoles 4a–l was synthesized by reacting 2,5-dihydroxyphenacyl bromide with various 4-aryl thiosemicarbazones 3a–l that on oxidation with ferric chloride yielded the corresponding N ¹-substituted benzylidene-N ²-[3-aryl-4-(1,4-benzoquinon-2-yl)-1,3-thiazol-2-ylidene]hydrazines 5a–l. They were evaluated for antibacterial activity against Staphylococcus aureus and Bacillus subtilis as Gram-positive bacteria, Escherichia coli and Pseudomonas aeruginosa as Gram-negative bacteria. They were also evaluated for their in vitro antifungal potential against Candida albicans. Almost all tested compounds were found to possess variable degrees of antimicrobial activity. The obtained data revealed that compounds 4b–h and 5e, 5f and 5l exhibited promising antimicrobial activity against the tested organisms of which compound 4b proved to be the most active.     

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.     

New thiazolidine-2,4-diones as antimicrobial and cytotoxic agent

New (Z)-5-substituted-2,4-thiazolidinediones (3a–m) were easily prepared by the condensation of thiazolidine-2,4-dione (1) with suitable aldehydes (2a–m) via microwave irradiation technique. The reaction between (Z)-5-substituted-2,4-thiazolidinediones and 4-(bromomethyl) benzoic acid, using potassium carbonate as base in refluxing acetone, followed by a workup in acidic medium provided 4-(((Z)-5-substituted-2,4-dioxothiazolidin-3-yl)methyl) benzoic acid derivatives (4a–m). The structures of the newly synthesized compounds were confirmed by IR, ¹H NMR, ¹³C NMR spectral studies, and elemental analysis. All compounds were evaluated for their in vitro antimicrobial and cytotoxic activities. Antibacterial and antifungal results revealed that most of the compounds showed significant activity where as compounds 4c and 4g are found to be broad spectrum antibacterial and antifungal properties, the MIC values were observed in the range of 2–4 and 2–8?μg/ml, respectively. In MTT cytotoxicity studies, the compound 4g was found most potent. In HeLa, HT29, A549, and MCF-7 cells, the IC₅₀ values were observed in the range of 30–36?μM.     

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 biological evaluation of some N 4-aryl-substituted 5-fluoroisatin-3-thiosemicarbazones

A series of N ⁴-aryl-substituted 5-fluoroisatin-3-thiosemicarbazones 3a–3l was synthesized and evaluated for selected biological activities. The brine shrimp lethality bioassay was carried out to study their in vitro cytotoxicity potential and besides, their antifungal, phytotoxic and urease inhibitory effects were also investigated. Seven compounds i.e. 3a, 3d, 3f, 3g, 3h, 3j and 3k proved to be active in the brine shrimp assay, displaying promising cytotoxicity (LD₅₀ = 6.89 × 10^?5–2.79 × 10^?4 M). Amongst these, 3a and 3h were found to be the most active ones (LD₅₀ = 6.89 × 10^?5 and 9.79 × 10^?5 M, respectively). Compounds 3i, 3j and 3 k displayed moderate (40 %) antifungal activity against one or two fungal strains i.e. A. flavus and/or M. canis. In phytotoxicity assay, all the synthesized compounds, including the reference point 2m showed weak-to-moderate (15–70 %) activity at the highest tested concentration (500 μg/mL). In urease inhibition assay, compounds 3f, 3g and 3j proved to be the most potent inhibitors, demonstrating relatively a higher degree of enzymatic inhibition with IC₅₀ values ranging from 37.7 to 47.3 μM.     

Synthesis of new olefin chalcone derivatives as antitumor, antioxidant and antimicrobial agents

Chalcone is a unique template that is associated with several biological activities. Claisen–Schmidt condensation of olefin aldehyde 3 and various mono, disubstituted and heterocyclic acetophenones afforded novel olefin chalcones. Synthesized compounds were subjected for ADME prediction by computational method which revealed that these molecules can be considered as a potential drug. Out of the 21 compounds screened, compounds 5u, 5g, 5c and 5e have shown significant cytotoxicity against Hep 3BPN 7, compounds 5j, 5i, 5n and 5o showed good cytotoxicity against HL 60 P 58. Compounds 5f, 5c, 5e and 5b showed potent cytotoxicity against Hela B 75. Antioxidant activity was assessed using three methods, namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical scavenging and ferric reducing antioxidant power (FRAP). The result shows that all these compounds possess significant antioxidant activity. Compounds 5k, 5s, 5a and 5c showed promising antibacterial activity. Compounds 5k, 5u and 5f could be considered as chemopreventive agents.     

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, 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.     

Novel indolyl-pyrimidine derivatives: synthesis,antimicrobial, and antioxidant evaluations

In the present study, a novel series of indolyl-pyrimidines (1–13) were synthesized starting from 4-hydrazinopyrimidine-5-carbonitrile 3. Elemental analysis, IR, ¹H-NMR, ¹³C-NMR, and mass spectral data elucidated structure of newly synthesized compounds. All compounds were screened for their in vitro antibacterial, antifungal, and some for antioxidant activities. Compounds 5, 9g, 9i, and 9j showed pronounced antimicrobial activity against Staphylococcus aureus, Bacillus cereus, Escherichia coli, Candida albicans, and Aspergillus flavus compared to the reference drugs, while compounds 3 and 9g displayed promising free radical scavenging activity and found to be more potent than standard, ascorbic acid (vitamin C). Further, some compounds were evaluated for cytotoxic activity by SRB assay method against human colon carcinoma (CaCo-2) and showed that compounds 4 and 9g were found to be the highly active compared to the reference drug doxorubicin. Their structure and activity relationship were discussed.     

Synthesis of new quinoline-2-pyrazoline-based thiazolinone derivatives as potential antimicrobial agents

A series of 2-(5-(2-chloro-6-methylquinolin-3-yl)-3-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)ones (4a–l) were synthesized and characterized by IR, ¹H NMR, ¹³C NMR, and mass spectra. All the synthesized compounds were tested for their in vitro antimicrobial activity 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. Compounds 4e, 4f, 4g, 4i, 4j, and 4l were the most distinctive derivatives identified in present study because of their remarkable in vitro antimicrobial potency.