N-heteroatom substitution effect in 3-aza-cope rearrangements.

BACKGROUND: The nature of the heteroatom substitution in the nitrogen of a 3-aza-Cope system is explored. RESULTS: While N-propargyl isoxazolin-5-ones suffer 3-aza-Cope rearrangements at 60°C, the corresponding N-propargyl pyrazol-5-ones need a higher temperature of 180°C for the equivalent reaction. When the propargyl group is substituted by an allyl group, the temperature of the rearrangement for both type of compounds is less affected by the nature of the heteroatom present. Treatment with a base, such as ethoxide, facilitates the rearrangement, and in the case of isoxazol-5- ones other ring opening reactions take precedence, involving N-O ring cleavage of the 5-membered ring. However when base-catalysed decomposition is prevented by substituents, products arising from a room temperature aza-Cope rearrangement are isolated. A possible mechanistic pathway based on free energies derived from density functional calculations involving cyclic intermediates is proposed. CONCLUSIONS: The nature of the heteroatom substitution in the nitrogen of a 3-aza-Cope system leads to a remarkable difference in the energy of activation of the reaction.

Aza vinyl sulfones: synthesis and evaluation as antiplasmodial agents.

A series of novel aza vinyl sulfones were designed, synthesized in good yields and evaluated as antiplasmodial agents. Tested compounds did not show activity against papain or the Plasmodium falciparum cysteine protease falcipain-2. However, a number of the new compounds effectively inhibited the in vitro development of P. falciparum. Compounds containing a squaramide group were the most active, with IC(50) values between 0.95 and 4.5 µM, suggesting that these are potential lead compounds for the development of new antimalarial agents.

Aspartic vinyl sulfones: inhibitors of a caspase-3-dependent pathway.

In this article we describe an expanded structure-activity relationship study for vinyl sulfones as caspase-3 inhibitors, a topic virtually unexplored in the existing literature. Most remarkably, and to our surprise, tripeptidyl vinyl sulfones were not active for caspase-3, opposite to other examples described in literature for peptidyl vinyl sulfones as potent cysteine protease inhibitors of clan CA. Moreover, the caspase-3 inhibitory activity of vinyl sulfones using an in vitro assay was then confirmed using a yeast cell-based assay. The results show that Fmoc-protected vinyl sulfones containing only the Asp moiety are inhibitors of a caspase-3-dependent pathway and the IC50 values obtained in the yeast assay are in the same order of magnitude of that obtained with the caspase-3 inhibitor tetrapeptidyl chloromethyl ketone, Ac-DEVD-CMK. This observation is consistent with appropriate cell permeability properties displayed by the vinyl sulfone inhibitors, as reflected by logP values ranging from 1.1 to 3.4. Overall, these results suggest that vinyl sulfones containing Asp at P1 should be considered for further optimization as caspase inhibitors and modulators of caspase-3-dependent pathways.

Cell death targets and potential modulators in Alzheimer's disease.

Apoptosis is now recognized as a normal feature in the development of the nervous system and may also play a role in neurodegenerative disorders, such as Alzheimer's disease. Cell surface receptors, caspases, mitochondrial factors or p53 participate in the modulation and execution of cell death. Therefore, the ability to understand and manipulate the cell death machinery is an obvious goal of medical research. Potential therapeutic approaches to modulate disease by regulating apoptosis are being tested, and include the traditional use of small molecules to target specific players in the apoptosis cascade. As our understanding of apoptosis increases, further opportunities will arise for more specific therapies that will result in improved efficacy. This review focuses on molecular mechanisms of apoptosis in Alzheimer's disease and highlights the potential use of small molecule modulators to treat neurodegenerative disorders.

Synthesis and evaluation of vinyl sulfones as caspase-3 inhibitors. A structure-activity study.

The first structure-activity relationship study of vinyl sulfones as caspase-3 inhibitors is reported. A series of 12 vinyl sulfones was synthesized and evaluated for two downstream caspases (caspases-3 and -7). Dipeptidyl derivatives were significantly superior to their counterparts containing only Asp at P(1), as caspase-3 inhibitors. Fmoc-Val-Asp-trans-CH=CH-SO(2)Me was the most potent inhibitor of caspase-3 in the series, with a IC(50) of 29 microM and a second-order rate constant of inactivation, k(inact)/K(i), of 1.5 M(-1) s(-1). Computational studies suggest that the second amino acid occupies position S(3) of the enzyme. In addition, Fmoc-Val-Asp-trans-CH=CH-SO(2)Ph was inactive for caspase-7 for the tested concentrations.

[Monitoring antibiotic consumption in the surgery and orthopaedics]. / Monitorização do consumo de antibióticos: nos serviços de cirurgia e de ortopedia de seis hospitais SA.

Monitoring antibiotic consumption is a valuable tool which has been increasingly used in the last years due to the current concern with the emergence of resistant microbial strains. The present study aimed at monitoring antibiotic consumption, evaluating the economic impact of hospital antibiotic prescription and assessing the relationship between the prescribed antibiotics and the indications for either prophylactic or therapeutic use. This was a longitudinal pilot-study for which data were collected in six privately managed public hospital units during the month of May 2004, with a resulting sample of 1,122 admitted patients. We observed a prescription incidence rate of 76.9%, corresponding to a total of 1,154 dispensed antimicrobials, with a mean 71.2% of these antimicrobials being dispensed for the prophylaxis of surgical site infection (SSI). The mean cost of antibiotic courses was higher in cases of "suspected infection" (9.09 euro) or "confirmed infection" (8.74 euro) and lower in cases of "prophylaxis" (5.67 euro), a finding which is explained by the shorter mean duration of the later. There was a considerable variation among the different hospital units regarding the type of antibiotic compound that was used for SSI prophylaxis, with a mean duration of antibiotic use of 2.61 days for this indication and about half of the prophylactic regimens lasting longer than 24 hours, a fact that suggests an insufficient observation of the current recommendations for antibiotic use in SSI prophylaxis. This finding indicates the need for an investigation on the actual existence of local recommendations for SSI prophylaxis in individual hospital units and also for the evaluation of the compliance of practicing surgeons with eventually existing recommendations.

Studies in 3-oxy-assisted 3-aza cope rearrangements.

On thermolysis appropriately substituted N-silyloxy-N-allyl enamines undergo smooth 3,3-sigmatropic rearrangments to the corresponding N-silyloxy imino ethers.