Structural bases for substrate and inhibitor recognition by matrix metaloproteinases

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases which are involved in the proteolytic processing of several components of the extracellular matrix. As a consequence, MMPs are implicated in several physiological and pathological processes, like skeletal growth and remodelling, wound healing, cancer, arthritis, and multiple sclerosis, raising a very widespread interest toward this class of enzymes as potential therapeutic targets. Here, structure-function relationships are discussed to highlight the role of different MMP domains on substrate/inhibitor recognition and processing and to attempt the formulation of advanced guidelines, based on natural substrates, for the design of inhibitors more efficient in vivo. © 2008 Bentham Science Publishers Ltd

Recent Advances on Type-2 Cannabinoid (CB2) Receptor Agonists and their Therapeutic Potential

In the last decade, selective modulators of type-2 cannabinoid receptor (CB2) have become a major focus to target endocannabinoid signaling in humans. Indeed, heterogeneously expressed within our body, CB2 actively regulates several physio-patho-logical processes, thus representing a promising target for developing specific and safe therapeutic drugs. If CB2 modulation has been extensively studied since the very beginn-ing for the treatment of pain and inflammation, the more recent involvement of this receptor in other pathological conditions has further strengthened the pursuit of novel CB2 agonists in the last five years. Against this background, here we discuss the most recent evidence of the protective effects of CB2 against pathological conditions, emphasizing central nervous system disor-ders, bone and synovial diseases, and cancer. We also summarize the most recent advances in the development of CB2 agonists, focusing on the correlation between different chemical classes and diverse therapeutic applications. Data mining includes a review of the CB2 ligands disclosed in patents also released in the last five years. Finally, we discuss how the recent elucidation of CB2 tertiary structure has provided new details for the rational design of novel and more selective CB2 agonists, thus supporting innovative strategies to develop effective therapeutics. Our overview of the current knowledge on CB2 agonists provides pivotal information on the structure and function of different classes of molecules and opens possible avenues for future research

Conformational Change in the Mechanism of Inclusion of Ketoprofen in β- Cyclodextrin: NMR Spectroscopy, Ab Initio Calculations, Molecular Dynamics Simulations and Photoreactivity

Inclusion of drugs in cyclodextrins is a recognised tool for modifying several properties such as solubility, stability, bioavailability and more. The photoreactive behavior of the β-Cyclodextrin/Ketoprofen complex upon UV exposure showed a significant increase of the photo-decarboxylation while the secondary degradation products by hydroxylation of the benzophenone moiety were inhibited. The results may account for an improvement of Ketoprofen photophysical properties upon inclusion, thus fostering better its topical use. To correlate the structural details of the inclusion with these results a NMR spectroscopic study of Ketoprofen upon inclusion in β-Cyclodextrin was performed. Effects of the magnetically anisotropic centers of ketoprofen, changing their orientations upon inclusion giving chemical shift variations, were specifically correlated to the results of the molecular dynamic simulations and ab initio calculations. In the large variety of papers focusing on the structural analysis of β-cyclodextrin complexes, this work represents one of the few examples in which a detailed analysis of these simultaneous upfield-downfield NMR shifts of the same aromatic molecule upon inclusion is reported. Interestingly the results demonstrate that the observed upfield and downfield shifts upon inclusion are not related to any direct magnetic role of the  cyclodextrin. The conformational change of Ketoprofen upon the inclusion process consists in a slight reduction of the angle between the two phenyl rings and in a remarkable reduction of the mobility of the carboxyl group, the latter being one of the main contributions to the NMR resonances shifts. These structural details help in understanding of the inclusion complex features and, eventually, of the driving force for its formation

Nitazoxanide Inhibits Paramyxovirus Replication by Targeting the Fusion Protein Folding: Role of Glycoprotein-Specific Thiol Oxidoreductase ERp57

Paramyxoviridae, a large family of enveloped viruses harboring a nonsegmented negative-sense RNA genome, include important human pathogens as measles, mumps, respiratory syncytial virus (RSV), parainfluenza viruses, and henipaviruses, which cause some of the deadliest emerging zoonoses. There is no effective antiviral chemotherapy for most of these pathogens. Paramyxoviruses evolved a sophisticated membrane-fusion machine consisting of receptor-binding proteins and the fusion F-protein, critical for virus infectivity. Herein we identify the antiprotozoal/antimicrobial nitazoxanide as a potential anti-paramyxovirus drug targeting the F-protein. We show that nitazoxanide and its circulating-metabolite tizoxanide act at post-entry level by provoking Sendai virus and RSV F-protein aggregate formation, halting F-trafficking to the host plasma membrane. F-protein folding depends on ER-resident glycoprotein-specific thiol-oxidoreductase ERp57 for correct disulfide-bond architecture. We found that tizoxanide behaves as an ERp57 non-competitive inhibitor; the putative drug binding-site was located at the ERp57-b/b′ non-catalytic domains interface. ERp57-silencing mimicked thiazolide-induced F-protein alterations, suggesting an important role of this foldase in thiazolides anti-paramyxovirus activity. Nitazoxanide is used in the clinic as a safe and effective antiprotozoal/antimicrobial drug; its antiviral activity was shown in patients infected with hepatitis-C virus, rotavirus and influenza viruses. Our results now suggest that nitazoxanide may be effective also against paramyxovirus infection

Design, Synthesis, and Biological Evaluation of Tetrahydro-β-carboline Derivatives as Selective Sub-Nanomolar Gelatinase Inhibitors

Targeting matrix metalloproteinases (MMPs) is a pursued strategy for treating several pathological conditions, such as multiple sclerosis and cancer. Herein, a series of novel tetrahydro-β-carboline derivatives with outstanding inhibitory activity toward MMPs are present. In particular, compounds 9 f, 9 g, 9 h and 9 i show sub-nanomolar IC50 values. Interestingly, compounds 9 g and 9 i also provide remarkable selectivity toward gelatinases; IC50 =0.15 nm for both toward MMP-2 and IC50 =0.63 and 0.58 nm, respectively, toward MMP-9. Molecular docking simulations, performed by employing quantum mechanics based partial charges, shed light on the rationale behind binding involving specific interactions with key residues of S1' and S3' domains. Taken together, these studies indicate that tetrahydro-β-carboline represents a promising scaffold for the design of novel inhibitors able to target MMPs and selectively bias gelatinases, over the desirable range of the pharmacokinetics spectrum