Antimicrobials. New nitrofuran derivatives

Design, synthesis and inhibitory activity against Candida albicans of a series of derivatives with 5-nitrofuran scaffold

The increasing resistance of Candida albicans against the currently available antifungal drugs has exerted enormous damage to human health. To develop novel and efficient antifungal agents with unique structure, a series of derivatives containing 5-nitrofuran scaffold (33 examples) were designed, synthesized, and screened the in vitro antifungal activities. Bioassay results disclosed that 5-nitrofuran derivatives could dramatically inhibit the growth of six strains of Candida albicans, particularly the drug-resistant clinical ones. There were ten kinds of compounds exhibited stronger inhibitory activities against tested fungi than those of fluconazole. For all tested fungi, B5 showed the highest activity with the MIC80 values of 0.25-8 µg/mL. The results of cytotoxicity assay displayed that B5 hardly influenced the growth of HL-7702 cell lines, consequently, it was safe for people and animals. The preliminary exploration of antifungal mechanism documented that B5 could destroy the morphology of tested fungi, facilitate the formation of reactive oxygen species, ultimately inhibited the proliferation of the tested fungi. In conclusion, a new and safe lead compound was successfully developed for the treatment of Candida albicans infection.

Recent Advances in Apoptosis: THE Role of Hydrazones

The process of programmed cell death in higher eukaryotes (apoptosis), is generally characterized by distinct morphological characteristics and energy-dependent biochemical mechanisms. Apoptosis is considered as a vital component of various processes including normal cell turnover, proper development and functioning of the immune system, hormone-dependent atrophy, embryonic development and chemical-induced cell death. Apoptosis seems to play an important key role in the progression of several human diseases like Alzheimer's disease, Parkinson's disease and many types of cancer. Promotion of apoptosis may be a good approach for the prevention of cancer cell proliferation. In early studies, antitumor compounds have been found to induce the apoptotic process in tumor cells. On the other hand, several hydrazones were reported to have lower toxicity than hydrazides due to the blockage of -NH2 group. Therefore, the design of hydrazones that activate and promote apoptosis is an attractive strategy for the discovery and development of potential anticancer agents. The aim of this review is to provide a general overview of current knowledge and the connection between apoptosis and hydrazone. It is also the guide for the apoptotic activities of new hydrazone derivatives.

Synthesis of some novel hydrazono acyclic nucleoside analogues

The syntheses of novel hydrazono acyclic nucleosides similar to miconazole scaffolds are described. In this series of acyclic nucleosides, pyrimidine as well as purine and other azole derivatives replaced the imidazole function in miconazole and the ether group was replaced with a hydrazone moiety using phenylhydrazine. To interpret the dominant formation of (E)-hydrazone derivatives rather than (Z)-isomers, PM3 semiempirical quantum mechanic calculations were carried out which indicated that the (E)-isomers had the lower heats of formation.

An efficient synthesis of bis(indolyl)methanes and evaluation of their antimicrobial activities

A versatile and efficient method has been developed for the synthesis of bis(indolyl)methanes by using aluminium triflate (0.5 mol%) as a novel catalyst. Further, some of the synthesized compounds were evaluated for their efficacy as antibacterial and antifungal activities. Most of the compounds have shown moderate to good inhibitory activity.

Anti-tubercular agents. Part IV: Synthesis and antimycobacterial evaluation of nitroheterocyclic-based 1,2,4-benzothiadiazines

In continuation of our earlier work on benzothiadiazines, we have prepared a series of nitrofuran, nitrothiophene and arylfuran coupled benzothiadiazines and evaluated them for antimycobacterial and antibacterial activities. One of the compounds 2f has shown good in vitro antimycobacterial activity. All the synthesized compounds have shown moderate to good antibacterial activity.

Similarities and differences between azomethines and ketimines: synthesis, materials characterization and structure of novel imines compounds

Imines (ketimines and azomethines) derived from p-dibenzoylbenzene (DB) and terephthalic aldehyde (TA) and two aromatic amines: aniline and 2,6-dimethylaniline have been investigated. Compounds were synthesized via condensation of amines with carbonyl monomers in DMA or amine solution. When using DMA as a solvent, azomethines with high yields were obtained. On the other hand, the amines used as a monomers served also as an effective solvent for the synthesis of the ketanils. This different reactivity of the aldehyde and ketone groups in DMA and in amine depends on the dehydration mechanism being dominated by a kinetic process or thermodynamic one. On the basis of FTIR, 13C and 1H NMR, UV-vis spectra, thermal characteristic and theoretical calculations conclusions are drawn regarding the similarities and differences between azomethines and ketimines.

Synthesis and biological activities of diflunisal hydrazide–hydrazones

Several diflunisal hydrazide-hydrazone derivatives namely 2',4'-difluoro-4-hydroxybiphenyl-3-carboxylic acid [(5-nitro-2-furyl/substitutedphenyl)methylene] hydrazide (3a-o) have been synthesised. Methyl 2',4'-difluoro-4-hydroxybiphenyl-3-carboxylate (1) and 2',4'-difluoro-4-hydroxybiphenyl-3-carboxylic acid hydrazide (2) were also synthesised and used as intermediate compounds. All synthesised compounds were screened for their antimycobacterial activity against Mycobacterium tuberculosis H37 Rv, antimicrobial activities against various bacteria, fungi and yeast species. Compound 3a have shown activity against Staphylococcus epidermis HE-5 and Staphylococcus aureus HE-9 at 18.75 and 37.5 microg mL(-1), respectively. Compound 3o have exhibited activity against Acinetobacter calcoaceticus IO-16 at a concentration of 37.5 microg mL(-1), whereas Cefepime, the drug used as standard, have been found less active against the microorganisms mentioned above. The synthesised compounds were found to provide 12-34% inhibition of mycobacterial growth of M. tuberculosis H37 Rv in the primary screen at 6.25 microg mL(-1). Anticonvulsant activity of the compounds were also determined by maximal electroshock (MES) and subcutaneous metrazole (scMET) tests in mice and rats following the procedures of antiepileptic drug development (ADD) program of the National Institutes of Health (NIH). Compound 3k showed 25% protection against MES induced seizures in p.o. rat screening at a dose level of 30 mg kg(-1) whereas 3n and 3o showed neurotoxicity after 4 and 0.5 h at a dose level of 100 and 300 mg kg(-1), respectively.

Synthesis, characterization and pharmacological properties of some 4-arylhydrazono-2-pyrazoline-5-one derivatives obtained from heterocyclic amines

The synthesis of a new series of 4-arylhydrazono-2-pyrazoline-5-ones 7-24 and 22a is described. Structures of the synthesized compounds were confirmed using UV, IR, 1H-NMR, 13C-NMR and EI-mass spectral data. These compounds were tested in vitro against one Gram-positive and two Gram-negative bacterial strains, two mycobacterial strains and a fungus, Candida albicans. Compound 22 was found to be more active against Staphylococcus aureus than the other compounds at a concentration of 15.6 microg/mL. Some related compounds were evaluated for anticonvulsant activity. Compound 11 showed 40% protection against pentylenetetrazole-induced seizures in albino Swiss mice. In vitro antituberculosis activity of 4-arylhydrazono-2-pyrazoline-5-ones 7-12, 14-24, 22a and coupling products 6a-f were tested on Mycobacterium tuberculosis H37Rv. Of these compounds, only 24, which exhibited > 90% inhibition in the primary screen at 12.5 microg/mL against this strain was re-examined for determination of its actual MIC. However, level II assay revealed that the MIC value was not less than 12.5 microg/mL. The same compound was also tested against Mycobacterium avium, which was observed not to be susceptible to 24.

Structure-based design of non-peptide, carbohydrazide-based cathepsin K inhibitors

Using binding models which were based on the X-ray crystal structure of an amino acid-based active site-spanning inhibitor complexed with cathepsin K, Cbz-leucine mimics have been developed, leading ultimately to the design of a potent cathepsin K inhibitor free of amino acid components. These mimics, which consist of alpha-substituted biphenylacetyl groups in place of Cbz-leucine moieties, effectively mimic all aspects of the Cbz-leucine moieties which are important for inhibitor binding. The predicted directions of binding for the inhibitors were confirmed by mass spectral analysis of their complexes with cathepsin K, which gave results consistent with acylation of the enzyme and loss of the acylhydrazine portion of the inhibitor which binds on the S' side of the active site. The binding models were found to be very predictive of relative inhibitor potency as well as direction of inhibitor binding. These results strengthen the validity of a strategy involving iterative cycles of structure-based design and inhibitor synthesis and evaluation for the discovery of non-peptide inhibitors.