New Heterocyclic Compounds from Oxazol-5(4H)-one and 1,2,4-Triazin-6(5H)-one Classes: Synthesis, Characterization and Toxicity Evaluation.

This paper describes the synthesis of new heterocycles from oxazol-5(4H)-one and 1,2,4-triazin-6(5H)-one classes containing a phenyl-/4-bromophenylsulfonylphenyl moiety. The oxazol-5(4H)-ones were obtained via condensation of 2-(4-(4-X-phenylsulfonyl)benzamido)acetic acids with benzaldehyde/4-fluorobenzaldehyde in acetic anhydride and in the presence of sodium acetate. The reaction of oxazolones with phenylhydrazine, in acetic acid and sodium acetate, yielded the corresponding 1,2,4-triazin-6(5H)-ones. The structures of the compounds were confirmed using spectral (FT-IR, 1H-NMR, 13C-NMR, MS) and elemental analysis. The toxicity of the compounds was evaluated on Daphnia magna Straus crustaceans and on the budding yeast Saccharomyces cerevisiae. The results indicate that both the heterocyclic nucleus and halogen atoms significantly influenced the toxicity against D. magna, with the oxazolones being less toxic than triazinones. The halogen-free oxazolone had the lowest toxicity, and the fluorine-containing triazinone exhibited the highest toxicity. The compounds showed low toxicity against yeast cells, apparently due to the activity of plasma membrane multidrug transporters Pdr5 and Snq2. The predictive analyses indicated an antiproliferative effect as the most probable biological action. The PASS prediction and CHEMBL similarity studies show evidence that the compounds could inhibit certain relevant oncological protein kinases. These results correlated with toxicity assays suggest that halogen-free oxazolone could be a good candidate for future anticancer investigations.

Synthesis and Biological Evaluation of New N-Acyl-α-amino Ketones and 1,3-Oxazoles Derivatives.

In order to develop novel bioactive substances with potent activities, some new valine-derived compounds incorporating a 4-(phenylsulfonyl)phenyl fragment, namely, acyclic precursors from N-acyl-α-amino acids and N-acyl-α-amino ketones classes, and heterocycles from the large family of 1,3-oxazole-based compounds, were synthesized. The structures of the new compounds were established using elemental analysis and spectral (UV-Vis, FT-IR, MS, NMR) data, and their purity was checked by reversed-phase HPLC. The newly synthesized compounds were evaluated for their antimicrobial and antibiofilm activities, for toxicity on D. magna, and by in silico studies regarding their potential mechanism of action and toxicity. The 2-aza-3-isopropyl-1-[4-(phenylsulfonyl)phenyl]-1,4-butanedione 4b bearing a p-tolyl group in 4-position exhibited the best antibacterial activity against the planktonic growth of both Gram-positive and Gram-negative strains, while the N-acyl-α-amino acid 2 and 1,3-oxazol-5(4H)-one 3 inhibited the Enterococcus faecium biofilms. Despite not all newly synthesized compounds showing significant biological activity, the general scaffold allows several future optimizations for obtaining better novel antimicrobial agents by the introduction of various substituents on the phenyl moiety at position 5 of the 1,3-oxazole nucleus.

Synthesis, In Silico and In Vitro Evaluation of Antimicrobial and Toxicity Features of New 4-[(4-Chlorophenyl)sulfonyl]benzoic Acid Derivatives.

The multi-step synthesis, physico-chemical characterization, and biological activity of novel valine-derived compounds, i.e., N-acyl-α-amino acids, 1,3-oxazol-5(4H)-ones, N-acyl-α-amino ketones, and 1,3-oxazoles derivatives, bearing a 4-[(4-chlorophenyl)sulfonyl]phenyl moiety are reported here. The structures of the newly synthesized compounds were confirmed by spectral (UV-Vis, FT-IR, MS, 1H- and 13C-NMR) data and elemental analysis results, and their purity was determined by RP-HPLC. The new compounds were assessed for their antimicrobial activity and toxicity to aquatic crustacean Daphnia magna. Also, in silico studies regarding their potential mechanism of action and toxicity were performed. The antimicrobial evaluation revealed that the 2-{4-[(4-chlorophenyl)sulfonyl]benzamido}-3-methylbutanoic acid and the corresponding 1,3-oxazol-5(4H)-one exhibited antimicrobial activity against Gram-positive bacterial strains and the new 1,3-oxazole containing a phenyl group at 5-position against the C. albicans strain.

Design, Synthesis, Characterization and Antimicrobial Evaluation of Some Heterocyclic Condensed Systems with Bridgehead Nitrogen from Thiazolotriazole Class.

In the present study, a series of new heterocyclic condensed systems with bridgehead nitrogen from the thiazolo[3,2-b][1,2,4]triazoles class was synthesized starting from some 4-(4-X-phenylsulfonyl)phenyl)-4H-1,2,4-triazole-3-thioles 1a-c (X=H, Cl, Br). The intermediates of S-alkylated 1,2,4-triazoles, 2-(5-(4-(4-X-phenylsulfonyl)phenyl)-2H-1,2,4-triazol-3-ylthio)-1-(4-fluorophenyl)ethanones 2a-c, were obtained by treatment of triazoles 1a-c with 2-bromo-4'-fluoroacetophenone. The 2-(4-(4-X-phenylsulfonyl)phenyl)-6-(4-fluorophenyl)thiazolo[3,2-b][1,2,4]triazoles 3a-c were obtained by cyclization of S-alkylated 1,2,4-triazoles 2a-c in sulfuric acid media, at 0 °C. For the synthesis of 2-(4-(4-X-phenylsulfonyl)phenyl)-5-(4-fluorobenzylidene)-thiazolo[3,2-b][1,2,4]triazol-6(5H)-ones 4a-c, the triazoles 1a-c were treated with 4-fluorobenzaldehyde, chloroacetic acid and anhydrous sodium acetate, in the presence of acetic acid and acetic anhydride. The structures of the newly synthesized compounds have been confirmed by elemental analysis and spectral methods (IR, 1H-NMR, 13C-NMR, MS). The antimicrobial activity of all new compounds has been screened against some bacteria and yeasts.

Synthesis and antioxidant activity evaluation of new compounds from hydrazinecarbothioamide and 1,2,4-triazole class containing diarylsulfone and 2,4-difluorophenyl moieties.

In the present investigation, new hydrazinecarbothioamides 4-6 were synthesized by reaction of 4-(4-X-phenylsulfonyl)benzoic acids hydrazides (X=H, Cl, Br) 1-3 with 2,4-difluorophenyl isothiocyanate and further these were treated with sodium hydroxide to obtain 1,2,4-triazole-3-thione derivatives 7-9. The reaction of 7-9 with α-halogenated ketones, in basic media, afforded new S-alkylated derivatives 10-15. The structures of the synthesized compounds have been established on the basis of 1H-NMR, 13C-NMR, IR, mass spectral studies and elemental analysis. The antioxidant activity of all compounds has been screened. Hydrazinecarbothioamides 4-6 showed excellent antioxidant activity and 1,2,4-triazole-3-thiones 7-9 showed good antioxidant activity using the DPPH method.

New heterocyclic compounds from 1,2,4-triazole and 1,3,4-thiadiazole class bearing diphenylsulfone moieties. Synthesis, characterization and antimicrobial activity evaluation.

Some new 5-(4-(4-X-phenylsulfonyl)phenyl)-4-(R)-2H-1,2,4-triazol-3(4H)-thiones 4a,b; 5a,b and 5-(4-(4-X-phenylsulfonyl)phenyl)-N-(R)-1,3,4-thiadiazol-2-amines 6a,b; 7a,b were obtained by cyclization of new N(1)-[4-(4-X-phenylsulfonyl)benzoyl]-N(4)-(R)-thiosemicarbazides 2a,b; 3a,b (X=H, Br). The 1,2,4-triazoles were synthesized by intramolecular cyclization of acylthiosemicarbazides, in basic media. On the other hand, 1,3,4-thiadiazoles were obtained from same acylthiosemicarbazides, in acidic media. These new intermediates from thiosemicarbazide class were afforded by the reaction of 4-(4-X-phenylsulfonyl)benzoic acids hydrazides (X=H, Br) 1a,b with 4-trifluoromethoxyphenyl or 3,4,5-trimethoxyphenyl isothiocyanate. The newly synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR, MS and elemental analysis. All the new compounds were screened for their antimicrobial activity against some bacteria (Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 13061, Escherichia coli ATCC 25922, Enterobacter cloacae ATCC 49141, Acinetobacter baumannii ATCC 19606 and Pseudomonas aeruginosa ATCC 27853) and yeasts (Candida albicans ATCC 90028 and Candida parapsilosis ATCC 22019).

Synthesis and antimicrobial evaluation of some fused heterocyclic [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives.

A series of fused 1,2,4-triazoles with diphenylsulfone moiety are prepared utilizing 4-amino-5-[4-(4-X-phenylsulfonyl)phenyl]-4H-1,2,4-triazole-3-thiol 1 (X=H, Br). The latter on reaction with aromatic isothiocyanate in DMF, aromatic acid in POCl3 and CDI in dioxane gives five membered fused triazole derivatives 2a-c, 3a-c, 4a-g, 5a-g and 6a,b. The structures of newly synthesized compounds were confirmed on the basis of their elemental analysis and spectral data results (IR, 1H-and 13C NMR). New synthesized compounds were screened for their antimicrobial activities. The preliminary results revealed that some of the compounds exhibited promising antimicrobial activities.

Synthesis, characterization and antibacterial activity of some triazole Mannich bases carrying diphenylsulfone moieties.

A series of Mannich bases of 4-substituted 5-[4-(4-X-phenylsulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thiones, X=H, Cl, Br, 3 and 5 were synthesized and characterized on the basis of IR, NMR and elemental analyses. The potential antibacterial effects of the synthesized compounds were investigated using the Acinetobacter baumanii ATCC 19606; Citrobacter freundii ATCC 8090; Pseudomonas aeruginosa ATCC 9027; Enterococcus faecalis ATCC 19433; Staphylococcus aureus ATCC 12600; Staphylococcus epidermidis ATCC 14990; Bacillus subtilis ATCC 6633 strains. Some of them exhibited promising activities against A. baumanii and B. subtilis.