Synthesis and biological evaluation of [alpha-(1,5-disubstituted 1H-pyrazol-4-yl)benzyl]azoles, analogues of bifonazole

Insights into the interaction and binding mode of a set of antifungal azoles as inhibitors of potential fungal enzyme-based targets

Azole-containing compounds are a kind of chemical entities of natural and synthetic origin having a wide-range of activities. They are therefore considered as important moieties for fungicide development, mostly due to the possible action on several enzyme-based targets. As part of our research on fungicidal agents, the relationship between the ligand-enzyme affinities of several synthetic azole-containing compounds against a set of fungal enzyme-based targets was in silico evaluated through molecular docking. The affinity values of the test compounds were mostly higher than those of the respective test controls. Binding modes between enzymes and test compounds were firstly investigated through Vina scores and ligand-residue interactions. Furthermore, statistically relationships among docking scores were successfully found by multivariate analysis. They were mostly correlated with reported MIC₈₀ values, so it denoted an evident discrimination of the test compounds. Strong electron withdrawing groups on phenylacrylamide moiety were responsible for establishing stronger complexes with the enzyme targets, being trichodiene synthase and α-L-fucosidase the most important ones. Moreover, stability of a set of representative protein/ligand complexes was also analyzed by 10 ns molecular dynamics simulations (MD). Significant differences into the MD runs were detected and directly correlated to docking performances. Finally, docking affinity scores and HOMO-LUMO energy gaps resulted well predicted by comparative molecular field analysis (CoMFA) models, demonstrating the structure type is particularly associated with those calculated properties and these results were thus consistent with the respective validation parameters.

Synthesis and antimicrobial activities of novel 1,5-diaryl pyrazoles

Novel 1,5-diaryl pyrazole derivatives viz. 5-(4-chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazole-3-carboxamides (2a-e, 3, 3a-f), 2-(5-(4-chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazole-3-yl)thiazoles (6a-c,7, 8, 9a-c, 10, 11) were synthesized by varying the active part (amide group) of pyrazole, characterized using IR, (1)H NMR, mass spectral data and screened for their antibacterial activity against Escherichia coli (ATTC-25922), Staphylococcus aureus (ATTC-25923), Pseudomonas aeruginosa (ATTC-27853), Klebsiella pneumonia. Similarly all these compounds were screened for their antifungal activity against Aspergillus flavus (NCIM No. 524), Aspergillus fumigates (NCIM No. 902), Penicillium marneffei and Trichophyton mentagrophytes. Interestingly all the synthesized compounds exhibited good antibacterial (except 2a-c, 8, 9a) and antifungal activity (except 2a-c, 6a, 8, 9a).

Synthesis, antimicrobial activity and molecular modeling studies of halogenated 4-[1H-imidazol-1-yl(phenyl)methyl]-1,5-diphenyl-1H-pyrazoles

During the course of our studies in the azole antifungals area, we synthesized a number of 1,5-disubstituted 4-[1H-imidazol-1-yl(phenyl)methyl]-1H-pyrazoles, analogues of bifonazole. 1,5-Diphenyl-1H-pyrazole 3 showed weak antimycotic and antibacterial activities in vitro against Candida albicans, Cryptococcus neoformans and Staphylococcus aureus. In order to increase these properties, given that the halo substitution was found to be capable of enhancing antifungal effects, we prepared a series of fluoro and chloro derivatives of 3. The microbiological evaluation carried out on newly synthesized compounds included in vitro assays for antifungal, antibacterial and antimycobacterial activities. Among the tested compounds, some dichloro and trichloro-derivatives showed interesting antimicrobial properties. In particular, compounds 10j,k,l produced inhibitory effects against pathogen representatives of yeast (C. albicans, C. neoformans) and Gram positive bacteria (S. aureus) similar or superior to those of bifonazole. In addition, their activity against Mycobacterium tuberculosis was superior to that of clotrimazole and econazole, which were used as reference drugs. The replacement, in these compounds, of chlorine with fluorine atoms led to inactive derivatives. Docking studies were carried out on the most active compounds, in order to rationalize the pharmacological results.

Synthesis of some 1-(2,4-dihydroxythiobenzoyl)imidazoles, -imidazolines and -tetrazoles and their potent activity against Candida species

Various 1-(2,4-dihydroxythiobenzoyl)imidazoles, -imidazolines and -tetrazoles were synthesized and evaluated for their in vitro antifungal activity. Compounds were prepared by the reaction of sulfinyl-bis-(2,4-dihydroxythiobenzoyl) with properly substituted azoles. The MIC values against the Candida albicans ATCC 10231 strain, the azole-resistant clinical isolates of C. albicans and non-Candida species were determined. Tetrazole derivatives were the most active against C. albicans, imidazoline derivatives against non-Candida species. All compounds showed higher activity than that of comparable drugs.

Synthesis and antimycotic activity of N-azolyl-2,4-dihydroxythiobenzamides

N-pyrazole and N-1,2,4-triazole derivatives of 2,4-dihydroxythiobenzamide prepared from sulfinyl-bis-(2,4-dihydroxythiobenzoyl) and commercially available azole amines were tested for their antimycotic activity. The chemical structure of compounds was confirmed by IR, 1H NMR, MS and elemental analysis. The MIC values against the reference strain Candida albicans ATCC 10231, azole-resistant clinical isolates of Candida albicans and non-Candida albicans species were determined for their potential activity in vitro. The compounds exhibited comparable or higher activity than itraconazole and fluconazole tested under the same experimental conditions. Pyrazoline derivatives showed higher activity than other analogues. The strongest fungistatic activity for N-(2,3-dimethyl-1-phenyl-1,2-dihydro-5-oxo-5H-pyrazol-4-yl)-2,4-dihydroxythiobenzamide was found with MIC values significantly lower than those for the studied drugs.

Synthesis of Novel 3H-Quinazolin-4-ones Containing Pyrazolinone, Pyrazole and Pyrimidinone Moieties

The diazonium salt of 3-(4-aminophenyl)-2-methyl-3H-quinazolin-4-one (2a) and its 6-bromo derivative 2b reacted with some active methylene compounds, namely ethyl acetoacetate (3), ethyl cyanoacetate (4) and acetylacetone (5), to afford the corresponding hydrazono quinazolinone derivatives 6-8. Treatment of 6a,b with hydrazine hydrate or phenyl hydrazine in refluxing ethanol afforded the corresponding pyrazolin-5-one derivatives of 3H-quinazolin-4-one 9a-d. Cyclization of 7a,b with hydrazine hydrate yielded the corresponding products 10a,b. Reaction of 8a,b with phenyl hydrazine or with urea afforded the corresponding derivatives 11a,b and 12a,b, respectively. Compounds 6-12 were identified by C,H,N analysis, IR, ¹H-NMR, ¹³C-NMR and mass spectroscopy.

Synthesis and biological evaluation of azole derivatives, analogues of bifonazole, with a phenylisoxazolyl or phenylpyrimidinyl moiety

A series of azole derivatives, isoxazole or pyrimidine analogues of the antifungal drug bifonazole, were synthesized and tested in vitro against representative human pathogenic fungi (Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus). They were also evaluated as antibacterial agents against Staphylococcus aureus and Salmonella spp. Only 5-(imidazol-1-yl-phenylmethyl)-2,4-diphenyl-pyrimidine 7c showed weak antimicrobial activity (MIC = 66 microM) against C. albicans, C. neoformans and S. aureus. Results of biological tests proved, therefore, that replacement of the biphenyl portion of the bifonazole with a phenylisoxazolyl or phenylpyrimidinyl moiety is not profitable for antimicrobial properties.