Maria M. M. Santos

Michael Acceptors as Cysteine Protease Inhibitors

Cysteine proteases selectively catalyze the hydrolysis of peptide bonds. Uncontrolled, unregulated, or undesired proteolysis can lead to many disease states including emphysema, stroke, viral infections, cancer, Alzheimers disease, inflammation, and arthritis. Cysteine proteases inhibitors thus have considerable potential utility for therapeutic intervention in a variety of disease states. This review emphasizes on the new developments from literature reports on Michael acceptors as potential cysteine protease inhibitors, namely vinyl sulfones, alpha,beta-unsaturated carbonyl derivatives and aza-peptides. These compounds irreversibly alkylate the active site cysteine residue via conjugate addition. Examples of Michael acceptors inhibitors that have already progressed to clinical testing are also presented.

CSR in SMEs: strategies, practices, motivations and obstacles

Purpose - Given the greater recognition of the role played by small and medium-sized enterprises (SMEs) within the European economy, this research aims to provide an insight into SME CSR practices. Within this scope, the objective is to identify accurately and extensively: CSR practices at the social, economic and environmental levels; the motivations, perceived benefits, existing obstacles; and the types of support and strategies that render possible an explanation of the factors which place the greatest restrictions on SME adoption of CSR practices. Design/methodology/approach - This research was realized through the completion of a questionnaire type inquiry structured around table-based analysis. The questionnaire was sent out to a large sample of SMEs in Portugal. Findings - The main results demonstrate that, while CSR takes on an informal, non-structured character, it has been incorporated into the daily management of such companies. Furthermore, contrary to what happens at large companies, CSR at SMEs is fundamentally internally focused and results from attention to the potential benefits to the business from gains in eco-efficiency, a better social climate or a higher profile in the local community. The emphasis is on the adoption of simple, easily applicable and cheap measures and normally with specific results exemplifying how SME CSR is located on the border between entrepreneurialism and business management and that of business citizenship. Research limitations/implications - It is not possible to extrapolate the data obtained since the study focused only on mainland Portugal. Practical implications - The fact that the study clarifies the strategies and motivations of CSR in SMEs makes possible the development of active policies to promote CSR in the universe of these companies. Originality/value - Because the studies on SME CSR remain rare, this research contributes to a better understanding of the dynamics, motivations and strategies of CSR in the SMEs case.

Reaction of naphthoquinones with substituted nitromethanes. Facile synthesis and antifungal activity of naphtho[2,3-d]isoxazole-4,9-diones.

We report here a simple entry into naphtho[2,3-d]isoxazole-4,9-dione system containing a EWG in position 3 using the readily available 2,3-dichloro-1,4-naphthoquinone and nitromethyl derivatives in the presence of base. Antifungal activity of synthesised naphthoquinones was evaluated against ATCC and PYCC reference strains of Candida. The results suggest that the naphtho[2,3-d]isoxazole-4,9-dione scaffold has the potential to be developed into novel and safe therapeutic antifungal agents.

Enhancing macrocyclic diterpenes as multidrug-resistance reversers: structure-activity studies on jolkinol D derivatives.

The phytochemical study of Euphorbia piscatoria yielded jolkinol D (1) in a large amount, whose derivatization gave rise to 12 ester derivatives (2-13) and hydrolysis to compound 14. The in vitro modulation of P-gp of compounds 1-14 was evaluated through a combination of transport and chemosensitivity assays, using the L5178 mouse T lymphoma cell line transfected with the human MDR1 gene. Apart from jolkinol D, all derivatives (2-14) showed potential as MDR reversal agents. In this small library of novel bioactive macrocyclic lathyrane diterpene derivatives, designed to evaluate structure-activity relationships essential in overcoming multidrug resistance (MDR), some correlations between MDR reversal and molecular weight, accessible solvent areas, and octanol/water partition coefficient were identified that can contribute to the development of new selective P-gp reversal agents.

Enantioselective Formal Synthesis of (+)-Dihydrocorynantheine and (-)-Dihydrocorynantheol †

The enantioselective construction of the 3-ethylindolo[2,3-a]quinolizidine moiety present in numerous indole alkaloids is reported, the key steps being a stereoselective cyclocondensation of (S)-tryptophanol with an appropriate racemic delta-oxoester and a regio- and stereoselective cyclization of the resulting oxazolopiperidones on the lactam carbonyl group. A new procedure for the removal of the hydroxymethyl auxiliary group, involving oxidation to an aldehyde, dehydration of the corresponding oxime, and reductive decyanation of the resulting alpha-aminonitrile, has been developed. The preparation of indoloquinolizidine 27 represents a formal total synthesis of (+)-dihydrocorynantheine, (-)-dihydrocorynantheol, and other indolo[2,3-a]quinolizidine and oxindole alkaloids bearing the same substitution pattern.

Synthesis and evaluation of spiroisoxazoline oxindoles as anticancer agents.

Restoring p53 levels through disruption of p53-MDM2 interaction has been proved to be a valuable approach in fighting cancer. We herein report the synthesis and evaluation of eighteen spiroisoxazoline oxindoles derivatives as p53-MDM2 interaction inhibitors. Seven compounds showed an antiproliferative profile superior to the p53-MDM2 interaction inhibitor nutlin-3, and induced cell death by apoptosis. Moreover, proof-of-concept was demonstrated by inhibition of the interaction between p53 and MDM2 in a live-cell bimolecular fluorescence complementation assay.

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 Alzheimers 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 Alzheimers 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.

Enantioselective formal synthesis of ent-rhynchophylline and ent-isorhynchophylline

Starting from (S)-tryptophanol, a formal synthesis of ent-rhynchophylline and ent-isorhynchophylline, involving stereoselective cyclocondensation, spirocyclization, and alkylation reactions, and the final adjustment of the oxidation level at the oxindole and piperidine moieties, is reported.

Design, synthesis and evaluation of 3-methylene-substituted indolinones as antimalarials

The design, synthesis and evaluation of 3-methylene-substituted indolinones as falcipain inhibitors and antiplasmodial agents are described. These compounds react readily with thiols via an addition-elimination mechanism, indicating their potential as cysteine protease inhibitors. Several indolinones containing a Leu-i-amyl recognition moiety were found to be moderate inhibitors of the Plasmodium falciparum cysteine protease falcipain-2, but not of the related protease falcipain-3, and displayed antiplasmodial activity against the chloroquine-resistant P. falciparum W2 strain in the low micromolar range. Coupling a 7-chloroquinoline moiety to the 3-methylene-substituted indolinone scaffold led to a significant improvement in antiplasmodial activity.