Carbon-carbon-linked (pyrazolylphenyl)oxazolidinones with antibacterial activity against multiple drug resistant gram-positive and fastidious gram-negative bacteria

Catalytic and Multicomponent Reactions for Green Synthesis of Some Pyrazolone Compounds and Evaluation as Antimicrobial Agents

A green synthetic approach and facile method was developed to produce pyrazole compounds (6a-d) by the reaction of ethyl acetoacetate (1), hydrazines (2a-d), and catalytic imidazole (3) in aqueous media. 4-Dicyanomethylene-2-pyrazoline-5-one derivatives (14a-d) were synthesized through the reaction of 2-pyrazoline-5-one derivatives (6a-d) with tetracyanoethylene (TCE) (7) by using catalytic imidazole (3) in an aqueous medium. Moreover, the 4-dicyanomethylene derivative (16) was obtained via treatment of 1-phenyl-3,5-pyrazolidinedione (15) with TCE (7). The spiropyrazoleoxirane derivatives (18 and 20) were prepared by treating the precursor 4-dicyanomethylene-2-pyrazoline-5-one derivative (14b) with hydrogen peroxide in various polar solvents under alkaline conditions. The spiropyrazole oxirane derivative (18) was used as a precursor for the design of functionalized pyrazolone derivatives (24 and 27a, b). The chemical structure of the novel designed derivatives was ascertained based on elemental analyses, mp, thin-layer chromatography, and spectral analyses. Furthermore, some of the synthesized derivatives were examined against different pathogenic bacterial and fungal strains. Their results demonstrated that some of them revealed notable antimicrobial activities.

Novel Targets for Antimicrobials

Antimicrobial resistance (AMR) is the phenomenon developed by microorganism on exposure to antimicrobial agents, making them unresponsive. Development of microbial confrontation is a severe rising risk to global community well-being as treatment in addition, management of such resistant microbial infections is difficult and challenging. The situation requires action across all government sectors and society. The change in the molecular target on which antimicrobial drugs act is one of the key mechanisms behind AMR. One of the approaches to battle with AMR can be exploring newer molecular targets in microbes and discovering new molecules accordingly. There are various examples of novel targets such as biomolecules involving in biosynthesis of cell wall, biosynthesis of aromatic amino acid, cell disunion, biosynthesis of fatty acid, and isoprenoid biosynthesis and tRNA synthetases. Fatty acid biosynthesis (FAB) and their enzymes among all the above is the more appealing target for the advancement of new antimicrobial agents. Number of promising inhibitors have been developed for bacterial fatty acid synthesis (FAS) and also few of them are clinically used. Some of these potential inhibitors are found to be used in development of new antibacterial as a lead compound and have been discovered from high throughput screening processes like Platencimycin and their analogue, Platencin. The review majorly encompasses bacterial FAB in type II FAS system and potential inhibitors with respective targets of novel antibacterial.

Synthesis, Structure, and Antibacterial Activity of Novel 5-Arylpyrazole Derivatives

A series of novel 1-(acetyl,carboxamide,carbothioamide)substituted-5-(substituted-phenyl)-3-methy-4,5-dihydropyrazole derivatives have been synthesized and characterized by 1H NMR, IR, ESI-MS, and elemental analysis. Compounds 6h and 6q were further characterized by single crystal X-ray structural analysis. All of the compounds have been screened for their antibacterial potential in vitro against Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Pseudomonas fluorescens ATCC 13525, and Staphylococcus aureus ATCC 6538. Among the tested compounds, some of them display significant activity against the tested strains, and compounds 5ac and 6h show potent activity with a minimum inhibitory concentration value of 1.562 μg mL–1 against B. subtilis ATCC 6633, which is comparable to the positive control penicillin. Structure–effect relationships are also discussed based on the experimental data.

Synthesis and SAR of novel conformationally-restricted oxazolidinones possessing Gram-positive and fastidious Gram-negative antibacterial activity. Part 1: Substituted pyrazoles

A novel series of conformationally-restricted oxazolidinones was synthesized which possess a fused pyrazole ring substituted with various alkyl, aryl and heteroaryl substituents. A number of analogs exhibited potent activity against both gram-positive and fastidious gram-negative organisms.

Antileishmanial and Antibacterial Activity of a New Pyrazole Derivative Designated 4-[2-(1-(Ethylamino)-2-methyl- propyl)phenyl]-3-(4-methyphenyl)-1-phenylpyrazole

Here, we report for the first time the synthesis and the antileishmanial activity of a new pyrazole derivative, namely 4-[2-(1-(ethylamino)-2-methylpropyl)phenyl]-3-(4-methyphenyl)-1-phenylpyrazole). Micromolar concentrations of this compound were found to inhibit the in vitro multiplication of Leishmania tropica, Leishmania major, and Leishmania infantum, three species causing different forms of leishmaniasis. Furthermore, the 50% inhibitory concentration (IC50) values for the compound are only slightly higher than those of amphotericin B, one of the most active antileishmanial agents used as a satisfactory substitute in cases not responding to pentostam. The IC50 values after 48 h for L. tropica, L. major, and L. infantum promastigote growth were 0.48 microg/mL, 0.63 microg/mL and 0.40 microg/mL, respectively for the compound, while they were 0.23 microg/mL, 0.29 microg/mL and 0.24 microg/mL, respectively for amphotericin B. We also tested this compound for its antibacterial activity against several bacteria. The strongest antibacterial activity was observed against Entrococcus feacalis and Staphylococcus aureus with a minimal inhibitory concentration (MIC) of 60 microg/mL.

Synthesis and antibacterial activity of novel oxazolidinones bearing N-hydroxyacetamidine substituent

Novel oxazolidinone antibacterials containing N-hydroxyacetamidine moiety are synthesized with the diversity at C-5 terminus. These compounds have been evaluated against a panel of clinically relevant gram-positive and gram-negative pathogens. Most of the analogs in this series displayed activity superior to Linezolid and in vivo efficacies of selected oxazolidinones are also disclosed herein.

Effect of Pyrazoloquinoline Derivatives on the Growth ofLeishmania donovani Promastigotes

A screening study was conducted to examine the effect of a series of synthesized pyrazoloquinoline derivatives on the growth of Leishmania donovani promastigotes. Sixteen compounds were tested, ten of which showed an inhibitory effect on the growth of promastigotes. Compound 1 demonstrated potent antileishmanial activity, followed by compounds 3 and 7. Some compounds showed less significant activities, while others exhibited little or no activity. Some of these compounds may be potential candidates for future treatment of leishmaniasis.

A synthetic route to a novel type of conformationally constrained N-aryloxazolidinones

The synthesis of N-aryloxazolidinone 1, a conformationally constrained analog of linezolid embodying a tricyclic pyrrolo[1,2-a][4,1]benzoxazepine moiety as the N-aryl substituent, is reported. The synthetic route involves the successive construction of the pyrrole, oxazepine, and oxazolidinone rings, with incorporation of the isoxazolylamino moiety in the last synthetic steps.

1-Phenyl-3-toluyl-4-[ortho-1′-(N-ethyl-2′-methylpropylamine)]phenylpyrazole, synthesis and evaluation of the in vitro antifungal activity against Botrytis cinerea and Fusarium oxysporum

A novel antifungal pyrazole derivative was synthesized. Designated 1-phenyl-3-toluyl-4-[ortho-1'-(N-ethyl-2'-methylpropylamine)]phenylpyrazole, the compound exerted an antifungal effect toward Botrytis cinerea and Fusarium oxysporum. In fact, our results clearly show that mycelial growth and conidial germination of both fungi were blocked by the compound. Indeed, a 96-well microbioassay procedure was used for fast and easy evaluation of minimal inhibitory concentration (MIC). The MIC values for B. cinerea and F. oxysporum were 25 and 36 microg/ml, respectively.

QSPR of 3-aryloxazolidin-2-one antibacterials

A QSPR treatment has been applied to a data set consisting of 60 3-aryloxazolidin-2-one antibacterials to relate the in vitro minimum inhibitory concentration (MIC) (required to inhibiting growth of S. aureus) with theoretical molecular and fragment descriptors. The treatment using codessa pro descriptors leads to a seven-parameter model with r2 = 0.820 and r2cv = 0.758.

The synthesis and antimicrobial evaluation of a new series of isoxazolinyl oxazolidinones

A series of oxazolidinone antibacterial agents containing a 5-substituted isoxazol-3-yl moiety were synthesized via a nitrile oxide [3+2] dipolar cycloaddition reaction. These compounds were screened against a panel of susceptible and resistant Gram-positive organisms. Several analogs from this series were comparable to or more potent than linezolid in vitro.

The synthesis and antibacterial activity of 1,3,4-Thiadiazole phenyl oxazolidinone analogues

Replacement of the morpholine C-ring of linezolid 1 with a 1,3,4-thiadiazolyl ring leads to oxazolidinone analogues 5 having potent antibacterial activity against both gram-positive and gram-negative organisms. Conversion of the C5 acetamide group to a thioacetamide further increases the potency of these compounds.