Newer thiazolopyrimidine-based sulfonamides clubbed with benzothiazole moiety: synthesis and biological evaluation

A new class of thiazolopyrimidine-based sulfonamides (5a–j) was synthesized from a parent compound 2-methoxy benzoic acid by multistep reaction in order to find new agents to fight against microbial infections. Substituted thiazolopyrimidines (3a–e) were prepared by cyclocondensation of substituted thiazolidinediones (2a–e) with urea in the presence of acid catalyst P₂O₅. Finally, desired compounds (5a–j) were synthesized from intermediates (4a–e) prepared from compounds (3a–e) by chlorosulfonation followed by condensation with corresponding benzothiazole moiety. The synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR spectral data, and elemental analysis, and were evaluated for in vitro antimicrobial activity against certain bacterial and fungal strains using the broth microdilution method as well as antitubercular activity against H₃₇Rv using Lowenstein–Jensen agar method.     

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.     

Zn(OTf)2-catalyzed three component, one-pot cyclocondensation reaction of some new octahydroquinazolinone derivatives and access their bio-potential

An efficient synthesis of some new octahydroquinazolinone derivatives 4a–x by the cyclocondensation reaction of corresponding 2-thi(oxo)-1,2-dihydroquinoline-3-carbaldehyde 1a–e, 1,3-dicarbonyl compounds 2a–b, and substituted urea 3a–c using zinc triflate as a catalyst in refluxing ethanol in high yield is described. The structures of new compounds have been characterized on the basis of elemental analysis, FT- IR, ¹H NMR, ¹³C NMR, and mass spectral data. All the synthesized compounds were evaluated for their antimicrobial activities against various microbes. Minimum inhibitory concentration values of all the 24 synthesized compounds were also determined. Some of the synthesized compounds exhibited excellent antimicrobial 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,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 and pharmacological evaluation of some novel 2-pyrazolines bearing benzenesulfonamide as anti-inflammatory and blood glucose lowering agents

A series of novel pyrazolines (2a–l) bearing benzenesulfonamide moiety were synthesized by condensing appropriate chalcone (1a–l) with 4-hydrazinobenzenesulfonamide hydrochloride. Structure of all novel synthesized compounds was characterized on basis of elemental analysis data and spectral data (IR, ¹HNMR, MS). Compounds (2a–l) were screened for in vivo anti-inflammatory action in carrageenan-induced rat paw edema model and blood glucose lowering action in glucose fed hyperglycemic normal rats. Compounds 2a, 2e, and 2l showed significant anti-inflammatory action (more than 75 %) at 5 h and also showed superior gastrointestinal safety profiles as compared to celecoxib. One compound (2i) was found to exhibit significant blood glucose lowering activity.     

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.     

Design, synthesis, antimicrobial, anti-inflammatory, and analgesic activity of novel dihydrobenzo furo[3,2-e]isoxazolo[4,5-b]azepin-5(5aH)-ones

Novel series of dihydro benzofuro[3,2-e]isoxazolo[4,5-b]azepin-5(5aH)-ones 6 have been synthesized from 3,5-dimethyl-4-nitroisoxazole 1. Compound 1 on treatment with salicyl aldehydes afforded the corresponding nitrostyrylisoxazoles 3, which upon reaction with ethyl bromo acetate followed by cyclization with triethylamine furnished ethyl 2,3-dihydro-3-[(3-methyl-4-nitro-5-isoxazolyl)methyl]benzofuran-2-carboxylates 5. Reductive cyclization of compounds 5 was effected with SnCl₂–MeOH to give the title compounds 6. Compounds 4–6 were characterized by IR, ¹H NMR, ¹³C NMR and Mass spectral data. The title compounds 6a–g were evaluated for their antimicrobial, anti-inflammatory, LOX-5 inhibitory, and analgesic activity. Compounds 6b and 6c exhibited significant antimicrobial activity, potent anti-inflammatory and analgesic activities as that of standard drugs.     

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.     

Design and synthesis of niflumic acid-based N-acylhydrazone derivatives as novel anti-inflammatory and analgesic agents

A new series of niflumic acid-based N-acylhydrazone derivatives 5a–p were synthesized and evaluated for their anti-inflammatory and analgesic activities. Most of the compounds have shown anti-inflammatory activity with a moderate-to-excellent activity range (20–80 % reduction in inflammation). Among them, 3-chlorophenyl 5d and 3-pyridyl derivatives 5o exhibited the most potent anti-inflammatory activity relative to niflumic acid as the reference drug (77, 76, and 70 % reduction in inflammation at 1-h postdrug administration, respectively). Also, molecular simplification of niflumic acid through replacing the N-aryl group with N-methyl group produced compounds 6a–f with anti-inflammatory activity in a quite similar manner to those of their parent derivatives. In this subgroup, 4-pyridyl derivative 6f showed the most potent anti-inflammatory activity relative to niflumic acid (80 % reduction in inflammation at 1-h postdrug administration). The compounds with highest anti-inflammatory activity were subjected to analgesic assays and showed moderate-to-excellent analgesic activities. The compound 5j, 4-methoxy derivative, exhibited the highest analgesic activity relative to niflumic acid (97 and 68 % activity, respectively).     

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 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.     

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 and pharmacological evaluation of novel thienopyrimidine and triazolothienopyrimidine derivatives

Novel tricyclic thienopyrimidines (2, 3, 5, 8) and triazole-fused tetracyclic thienopyrimidines (6a–c and 9a–c) were synthesized from the precursor 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile (1). The structures of newly synthesized compounds were established by spectral and analytical data. The title compounds were screened for analgesic, anti-inflammatory, ulcerogenicity index, and antibacterial activities. Test compounds exhibited significant activity, the compounds (6a–c) and (9a–c) showed more potent analgesic activity, and the compounds (6c) and (9c) showed more potent anti-inflammatory activity than the reference standard Diclofenac Sodium. All the synthesized compounds exhibited remarkable antibacterial activity.     

Synthesis, anti-inflammatory, and cytotoxicity evaluation of 9,10-dihydroanthracene-9,10-α,β-succinimide and bis-succinimide derivatives

9,10-Dihydroanthracene-9,10-α,β-succinimide derivatives 4a–e and bis-succinimide derivatives 6a–e have been synthesized by grinding 9,10-dihydroanthracene-9,10-α,β-succinic anhydride 2 with various mono 3a–e and diamines 5a–e in quantitative yields. All the target compounds were fully characterized by spectrometric and spectroscopic means. Compounds 4a–e, 6a–e and recently reported compounds 4f–p were screened for anti-inflammatory and for cytotoxicity against five human cancer cell lines: T47D, NCI H-522, HCT-15, PA1, and HepG-2. Compounds 4e, 4i, 4j, and 4p exhibited good anti-inflammatory activity and compounds with interesting cytotoxic profile were 4c, 6e (T47D); 4e, 4o (NCI H-522); 4n (HCT-15); 4e, 4h, 4o (PA1); and 4a, 4e, 4f, 4i, 4o (HepG-2).     

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.     

Novel 2-(E)-substituted benzylidene-6-(N-substituted aminomethyl)cyclohexanones and cyclohexanols as analgesic and anti-inflammatory agents

Twenty-two new 2-(E)-substituted benzylidene-6-(N-substituted aminomethyl)cyclohexanones (6a–6j) and cyclohexanols (7a–7l) were designed and synthesized. Target compounds were obtained through Stork enamine, Mannich, and Grignard reactions taking cyclohexanone as starting material. The structures were confirmed by the application of IR, ¹H NMR, MS, and HR-MS data. The analgesic activities were evaluated by acetic acid-induced writhing test and hot plate method. The anti-inflammatory activities were assayed by xylene-induced ear swelling and carrageenan-induced paw edema in mice model. All tested compounds showed analgesic and anti-inflammatory capacities in oral administration. Some compounds (6a, 6c, 6h, 6i, 7c, 7h, and 7i) displayed the moderate analgesic activity compared with positive control ibuprofen, and some compounds (6a, 6b, 6d, 6h, 7a, and 7d) exhibited more anti-inflammatory activity than ibuprofen. Among them, compound 6a could be a potential nonsteroidal anti-inflammatory agent with significant analgesic activities and remarkable anti-inflammatory activities. Further research is being conducted.     

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, characterization, and in vitro antimicrobial evaluation of new 5-chloro-8-bromo-3-aryl-1,2,4-triazolo[4,3-c]pyrimidines

A series of new 5-chloro-8-bromo-3-aryl-1,2,4-triazolo[4,3-c]pyrimidines (4a–j) have been accomplished in excellent yields by the oxidative cyclization of pyrimidinylhydrazines (3a–j) of various aryl aldehydes with one equivalents of iodobenzene diacetate in methanol. The chemical structures of the synthesized compounds were confirmed by elemental analyses, FT-IR, ¹H NMR, ¹³C NMR, and mass spectral studies. Ten new compounds (4a–j) were tested in vitro for their antimicrobial activity against clinically isolated strains. Variable and modest activities were observed against the investigated strains of bacteria and fungi. Compounds 4f, 4i, and 4j demonstrated good antimicrobial activity against all the tested microbial strains.     

Synthesis, characterization, and biological evaluation of some N-aryl hydrazones and their 2,3-disubstituted-4-thiazolidinone derivatives

A series of 2,3-disubstituted 4-thiazolidinones 6 and 8a-p have been prepared by the cyclo condensation reaction of various substituted N-aryl hydrazones 5 and 7a–p with mercapto acetic acid. The intermediate N-aryl hydrazones 5 and 7a–p were synthesized by the condensation of 2-bromo-5-methoxy benzohydrazide 4 with 2 or various substituted aromatic aldehydes. The new Naphthalene-2-carboxaldehyde 2 has been synthesized by Vilsmeier-Haack reaction of naphthalen-1(2H)-one 1. The key starting compound 2-bromo-5-methoxy benzohydrazide 4 was prepared from methyl 2-bromo-5-methoxybenzoate 3 by the reaction with hydrazine hydrate in alcoholic medium. The formulae of the compounds were confirmed by elemental analyses and their structures were determined based on IR, ¹H-NMR, ¹³C-NMR, ¹³C-NMR-DEPT, and mass spectral data. The newly synthesized compounds were evaluated for their antioxidant, anti-inflammatory, and analgesic activities. The antibacterial activities of the newly synthesized compounds against E. coli ATCC 8739, S. aureus ATCC 6538, P. aeruginosa ATCC 1539, and Bacillus cereus, while the antifungal activities of the compounds against Candida albicans were tested. The acute cytotoxicity data of compounds 7h and 8a are tested and are found to be nontoxic up to 2,500 mg/kg.