Synthesis and Analysis of the Conformational Preferences of 5-Aminomethyloxazolidine-2,4-dione Scaffolds: First Examples of \u3b22- and \u3b22, 2-Homo-Freidinger Lactam Analogues

Constrained peptidomimetic scaffolds are of considerable interest for the design of therapeutically useful analogues of bioactive peptides. We present the single-step cyclization of (S)- or (R)-\u3b1-hydroxy-\u3b22- or \u3b1-substituted-\u3b1-hydroxy-\u3b22, 2-amino acids already incorporated within oligopeptides to 5-aminomethyl-oxazolidine-2,4-dione (Amo) rings. These scaffolds can be regarded as unprecedented \u3b22- or \u3b22, 2-homo-Freidinger lactam analogues, and can be equipped with a proteinogenic side chain at each residue. In a biomimetic environment, Amo rings act as inducers of extended, semi-bent or folded geometries, depending on the relative stereochemistry and the presence of \u3b1-substituents

Expedient synthesis of pseudo-Pro-containing peptides: Towards constrained peptidomimetics and foldamers

The reaction of sulfonyl peptides containing l- or d-configured Ser or Thr with bis(succinimidyl) carbonate in the presence of a catalytic amount of a base affords, in solution or in the solid phase, the corresponding peptides with one or two, consecutive or alternate oxazolidin-2-ones (Oxd). The Oxd ring can be regarded to as a pseudo-Pro with an exclusively trans conformation of the preceding peptide bond; homochiral Oxd-containing peptides adopt extended conformations, while the presence of a d-configured Oxd favours folded conformations. © The Royal Society of Chemistry 2012

Relationship between adipose tissue dysfunction, Vitamin D deficiency and the pathogenesis of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease ( NAFLD) is the most common chronic liver disease worldwide. Its pathogenesis is complex and not yet fully understood. Over the years many studies have proposed various pathophysiological hypotheses, among which the currently most widely accepted is the "multiple parallel hits" theory. According to this model, lipid accumulation in the hepatocytes and insulin resistance increase the vulnerability of the liver to many factors that act in a coordinated and cooperative manner to promote hepatic injury, inflammation and fibrosis. Among these factors, adipose tissue dysfunction and subsequent chronic low grade inflammation play a crucial role. Recent studies have shown that vitamin D exerts an immune-regulating action on adipose tissue, and the growing wealth of epidemiological data is demonstrating that hypovitaminosis D is associated with both obesity and NAFLD. Furthermore, given the strong association between these conditions, current findings suggest that vitamin D may be involved in the relationship between adipose tissue dysfunction and NAFLD. The purpose of this review is to provide an overview of recent advances in the pathogenesis of NAFLD in relation to adipose tissue dysfunction, and in the pathophysiology linking vitamin D deficiency with NAFLD and adiposity, together with an overview of the evidence available on the clinical utility of vitamin D supplementation in cases of NAFLD

Opioid activity profiles of oversimplified peptides lacking in the protonable N-terminus

Recently, we described cyclopeptide opioid agonists containing the D-Trp-Phe sequence. To expand the scope of this atypical pharmacophore, we tested the activity profiles of the linear peptides Ac-Xaa-Phe-Yaa (Xaa = L/D-Trp, D-His/Lys/Arg; Yaa = H, GlyNH2). Ac-D-Trp-PheNH2 appeared to be the minimal binding sequence, while Ac-D-Trp-Phe-GlyNH 2 emerged as the first noncationizable short peptide (partial) agonist with high \u3bc-opioid receptor affinity and selectivity. Conformational analysis suggested that 5 adopts in solution a \u3b2-turn conformation. \ua9 2012 American Chemical Society

In-Peptide Synthesis of Imidazolidin-2-one Scaffolds, Equippable with Proteinogenic or Taggable/Linkable Side Chains, General Promoters of Unusual Secondary Structures

Peptidomimetics containing (S)- or (R)-imidazolidin-2-one-4- carboxylate (Imi) have been obtained by the expedient in-peptide cyclization of (S)- or (R)-\u3b1,\u3b2-diaminopropionic acid (Dap) residues. These Imi scaffolds behave as proline analogues characterized by a flat structure and a transrestricted geometry of the preceding peptide bond and induce well-defined secondary structures in a biomimetic environment. While (S)-Imi peptides adopted a \u3b3\u2032-turn conformation, (R)-Imi induced the contemporary formation of a \u3b3-turn and a rare 11-membered H-bonded structure in the 2\u21924 opposite direction of the sequence, identified as a \u3b5-turn. In order to exploit these Imi scaffolds as general promoters of unusual secondary structures, proteinaceous side chains have been introduced at the N1 position of the five-membered ring, potentially mimicking any residues. Finally, the Imi rings have been equipped with unnatural side chains or with functionalized substituents, which can be utilized as linkers to chemoselectively bind the Imi-peptides onto nanoparticles, biomaterials, or diagnostic probes

In-peptide synthesis of di-oxazolidinone and dehydroamino acid-oxazolidinone motifs as \u3b2-turn inducers

Small and easy-to-do mimetics of \u3b2-turns are of great interest to interfere with protein-protein recognition events mediated by \u3b2-turn recognition motifs. We propose a straightforward procedure for constraining the conformation of tetrapeptides lacking a pre-formed scaffold. According to the stereochemistry array, N-Ts tetrapeptides including Thr or PhSer (phenylserine) at the positions 2 or 3 gave rise in a single step to the sequences Oxd 2-Oxd3 or \u394Abu2-Oxd3 (Oxd, oxazolidin-2-one; \u394Abu, 2,3-dehydro-2-aminobutyric). These pseudo-Pro residues displayed highly constrained, and \u3c7 dihedral angles, and induced clear \u3b2-turns or inverse turns of type I or II, as determined by extensive spectroscopic and computational analyses. \ua9 The Royal Society of Chemistry 2013

Integrin-Targeting Dye-Doped PEG-Shell/Silica-Core Nanoparticles Mimicking the Proapoptotic Smac/DIABLO Protein

Cancer cells demonstrate elevated expression levels of the inhibitor of apoptosis proteins (IAPs), contributing to tumor cell survival, disease progression, chemo-resistance, and poor prognosis. Smac/DIABLO is a mitochondrial protein that promotes apoptosis by neutralizing members of the IAP family. Herein, we describe the preparation and in vitro validation of a synthetic mimic of Smac/DIABLO, based on fluorescent polyethylene glycol (PEG)-coated silica-core nanoparticles (NPs) carrying a Smac/DIABLO-derived pro-apoptotic peptide and a tumor-homing integrin peptide ligand. At low \u3bcM concentration, the NPs showed significant toxicity towards A549, U373, and HeLa cancer cells and modest toxicity towards other integrin-expressing cells, correlated with integrin-mediated cell uptake and consequent highly increased levels of apoptotic activity, without perturbing cells not expressing the \u3b15 integrin subunit

Functional Selectivity and Antinociceptive Effects of a Novel KOPr Agonist

Kappa opioid receptor (KOPr) agonists represent alternative analgesics for their low abuse potential, although relevant adverse effects have limited their clinical use. Functionally selective KOPr agonists may activate, in a pathway-specific manner, G protein-mediated signaling, that produces antinociception, over \u3b2-arrestin 2-dependent induction of p38MAPK, which preferentially contributes to adverse effects. Thus, functionally selective KOPr agonists biased toward G protein-coupled intracellular signaling over \u3b2-arrestin-2-mediated pathways may be considered candidate therapeutics possibly devoid of many of the typical adverse effects elicited by classic KOPr agonists. Nonetheless, the potential utility of functionally selective agonists at opioid receptors is still highly debated; therefore, further studies are necessary to fully understand whether it will be possible to develop more effective and safer analgesics by exploiting functional selectivity at KOPr. In the present study we investigated in vitro functional selectivity and in vivo antinociceptive effects of LOR17, a novel KOPr selective peptidic agonist that we synthesized. LOR17-mediated effects on adenylyl cyclase inhibition, ERK1/2, p38MAPK phosphorylation, and astrocyte cell proliferation were studied in HEK-293 cells expressing hKOPr, U87-MG glioblastoma cells, and primary human astrocytes; biased agonism was investigated via cAMP ELISA and \u3b2-arrestin 2 recruitment assays. Antinociception and antihypersensitivity were assessed in mice via warm-water tail-withdrawal test, intraperitoneal acid-induced writhing, and a model of oxaliplatin-induced neuropathic cold hypersensitivity. Effects of LOR17 on locomotor activity, exploratory activity, and forced-swim behavior were also assayed. We found that LOR17 is a selective, G protein biased KOPr agonist that inhibits adenylyl cyclase and activates early-phase ERK1/2 phosphorylation. Conversely to classic KOPr agonists as U50,488, LOR17 neither induces p38MAPK phosphorylation nor increases KOPr-dependent, p38MAPK-mediated cell proliferation in astrocytes. Moreover, LOR17 counteracts, in a concentration-dependent manner, U50,488-induced p38MAPK phosphorylation and astrocyte cell proliferation. Both U50,488 and LOR17 display potent antinociception in models of acute nociception, whereas LOR17 counteracts oxaliplatin-induced thermal hypersensitivity better than U50,488, and it is effective after single or repeated s.c. administration. LOR17 administered at a dose that fully alleviated oxaliplatin-induced thermal hypersensitivity did not alter motor coordination, locomotor and exploratory activities nor induced pro-depressant-like behavior. LOR17, therefore, may emerge as a novel KOPr agonist displaying functional selectivity toward G protein signaling and eliciting antinociceptive/antihypersensitivity effects in different animal models, including oxaliplatin-induced neuropathy

A Genetic and Metabolic Staging System for Predicting the Outcome of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is an emerging cause of liver-related events (LREs). Here, we have assessed the ability of a composite score based on clinical features, metabolic comorbidities, and genetic variants to predict LREs. A total of 546 consecutive patients with NAFLD were recruited and stratified according to the fibrosis-4 (FIB-4) index. LREs were defined as occurrence of hepatocellular carcinoma or hepatic decompensation. Cox regression multivariate analysis was used to identify baseline variables associated with LREs. The UK Biobank was used as the validation cohort, and severe liver disease (incidence of cirrhosis, decompensated liver disease, hepatocellular carcinoma, and/or liver transplantation) was used as the outcome. LREs were experienced by 58 patients, only one of whom was in the cohort of patients with a FIB-4 score < 1.3. Multivariate Cox regression analysis of 229 patients with a FIB-4 score ≥ 1.3 highlighted clinical variables independently associated with the development of LREs, including older age, low platelet count, low albumin, low high-density lipoprotein cholesterol, certain genetic factors, and interactions between genetic factors and sex or diabetes. The area under the curve (AUC) for the model was 0.87 at 1, 3, and 5 years. Our novel Genetic and Metabolic Staging (GEMS) scoring system was derived from the Cox model linear predictor, ranked from 0 to 10, and categorized into five classes (0-5, 5-6, 6-7, 7-8, and 8-10). The risk of LREs increased from 4% in patients in the best class (GEMS score 0-5) to 91% in the worst (GEMS score 8-10). GEMS score was associated with incident severe liver disease in the study population (hazard ratio, 1.56; 95% confidence interval, 1.48-1.65; P < 0.001) as well as in the UK Biobank cohort where AUCs for prediction of severe liver disease at 1, 3, and 5 years were 0.70, 0.69, and 0.67, respectively. Conclusion: The novel GEMS scoring system has an adequate ability to predict the outcome of patients with NAFLD

Cribriform pattern does not have a significant impact in Gleason Score ≥7/ISUP Grade ≥2 prostate cancers submitted to radical prostatectomy

The aim of this study was to correlate cribriform pattern (CP) with other parameters in a large prospective series of Gleason score ≥7/ISUP grade ≥2 prostate cancer (PC) cases undergoing radical prostatectomy (RP)