Design and synthesis of new polycyclic compounds with potential anticancer activity

p53 is best known as a tumor suppressor that transcriptionally regulates, in response to cellular stresses such as DNA damage or oncogene activation, the expression of various target genes that mediate cell-cycle arrest, DNA repair, senescence or apoptosis—all of these cellular responses are designed to prevent damaged cells from proliferating and passing mutations on to the next generation. In 50% of human cancers, p53 is defective due usually to somatic mutations or deletions primarily in its DNA-binding domain and, to a lesser extent, to posttranslational modifications such as phosphorylation, acetylation and methylation that affect p53 function and stability. Altered p53 fails to regulate growth arrest and cell death upon DNA damage, directly contributing to tumor development, malignant progression, poor prognosis and resistance to treatment. Conversely, restoring endogenous p53 activity can halt the growth of cancerous tumors in vivo by inducing apoptosis, senescence, and innate inflammatory responses. cycle arrest, apoptosis, or senescence. While p53 plays a protective role in normal somatic tissues by limiting the propagation of damaged cells, its powerful growth suppressive and proapoptotic activity could be turned into a powerful weapon against cancer cells that have retained the functionality of the p53 pathway. Searching for small-molecules that activate the transcriptional activity of p53 would be expected to lead to the discovery of both DNA-damaging agents and compounds that are specific for the p53 pathway, including agents that interact directly with p53 or that inhibit MDM2 a negative regulator of p53 activity and stability. MDM2 is overexpressed in many human tumors and effectively impairs the function of the p53 pathway. Therefore, restoration of p53 function by antagonizing MDM2 has been proposed as a novel approach for treating cancer, and studies using macromolecular tools have shown its validity in vitro. II According to these findings, and as part of a wide medicinal chemistry program aimed at identifying small-molecules endowed with antitumor activity, different series of natural compound-inspired derivatives were designed as potential p53 modulators. Specifically, my PhD thesis work has been centered on two projects: the first was based on the design and synthesis of carbazole derivatives as DNA- damaging agents; while the second was based on the valuation of natural product analogues designed as both cellular cycle modulators and p53-MDM2 interaction inhibitors. The final aim of this study was to identify of suitable leads which allow us to deep on the molecular complexity of p53 network, improving the antitumor therapeutic arsenal The role of natural products as a source for remedies has been recognized since ancient times. Despite major scientific and technological progress in combinatorial chemistry, drugs derived from natural product still make an enormous contribution to drug discovery today. The development of novel agents from natural sources presents obstacles that are not usually met when one deals with synthetic compounds. For instance, there may be difficulties in accessing the source of the samples, obtaining appropriate amounts of the sample, identification and isolation of the active compound in the sample, and problems in synthesizing the necessary amounts of the compound of interest. An analysis of the number of chemotherapeutic agents and their sources indicates that over 60% of approved drugs are derived from natural compounds. During my PhD thesis work three different structural motives present in natural products have been considered to be suitable scaffold in the design of new antitumoral agents: carbazoles, acridines and spirooxindole derivatives. Carbazoles either in a pure substituted or in an annellated substituted form, represent an important and heterogeneous class of anticancer agents, which has grown considerably over the last two decades. Recently, Wong et al. have described a particular activity of a series of acridine derivatives characterized III by a polycyclic planar system and by a side chain ending with a tertiary amine, act stabilized p53 protein by blocking its ubiquitination, without phosphorylation of ser15 or ser20 on p53. Furthermore, these derivatives induced p53-dependent cell death, activating p53 transcriptional activity Based on the structural cytotoxic requirements for these class of products my first PhD project was centered on synthesis of two series of compounds in which a carbazole eskeleton were linked by an alkyl chain to an amine (series 1) or substituted amide (series 2) groups. In the other hand, small molecule natural products containing spirooxindole derivatives have demonstrated to be invaluable tools in the discovery and characterization of critical events for the progression and the regulation of the cell cycle. Based on the spirotryprostatin-A structure, during my PhD project II I designed, synthesized, and evaluated different series of compounds belonging to the diketopiperazine structural class as potential cell cycle modulators and cytotoxic agents. Starting from the spirooxindolthiazolidine scaffold, amide coupling with Pro derivatives and intramolecular cyclization reactions are suitable synthetic methods to generate chemically diverse diketopiperazine system, such as hexahydropyrrolo[1,2-a][1,3]thiazolo[3,2-d]pyrazine-5,10-dione (structure I), hexahydropyrrolo[1,2-a] [1,3]thiazolo[3,4-d]pyrazine-5,10-dione (structure II) and, spiroindol-2-one[3,30]hexahydro-5,10H-pyrrolo[1,2-a][1,3]thiazolo[3,4-d]pyrazine-5,10-dione (structure III). Some of these compounds, especially those who belong to the series I and II, showed interesting cytotoxic activity. In the last part of my project, I have designed and synthesized two libraries of compounds based on the spirooxindol-thyazolidine moiety, analogues of spirooxoindol-pyrrolidine template as p53-MDM2 inhibitors. Compounds (3R,7aR)-6-(4-chlorobenzyl)-1H-spiro[imidazo[1,5-c]thiazole-3,3‘-indoline]-2‘,5,7(6H,7aH)-trione (42c) and (3R,7aR)-50-methyl-6-(3,4,5-trimethoxybenzyl)-1H-spiro[imidazo-[1,5-c]thiazole-3,3‘-indoline]- IV 2‘,5,7(6H,7aH)-trione (43d) are the most potent compounds of this series, inhibiting cell growth of different human tumor cells at submicromolar and micromolar concentrations, respectively. Compound 42c induces apoptotic cell death in human melanoma cell line M14 at 24 h, while in the same condition, treatment with 43d shows a clear arrest at G2/M phase inducing delay of cell cycle progression. Possibly, these activities may be due to inhibition of p53-MDM2 interaction and subsequent p53 release and activation. [edited by author]IX n.s

Relative echogenicity of tendons and ligaments of the palmar metacarpal region in foals from birth to 4 months of age: A longitudinal study

The objective of this study was to evaluate relative echogenicity of superficial and deep digital flexor tendons, the accessory ligament of the deep digital flexor tendon and interosseous muscle of the metacarpal region in foals ages 1 week to 4 months; and assess the association between echogenicity and sex or side/laterality. Seven Standardbred trotter foals were examined. Right and left metacarpal regions (palmar surface) were ultrasonographically investigated, and four regions of interest were assessed. A significant increase in echogenicity was seen in superficial and deep digital flexor tendons, accessory ligament of deep digital flexor tendon, and interosseous muscle during growth from 1 week to 4 months of age. Echogenicity of examined tendons and ligaments was not influenced by gender nor laterality. Reference values for tendon and ligament echogenicity could function as a tool to discriminate between physiological and abnormal conditions such as congenital contractural conditions

Overcome Chemoresistance: Biophysical and Structural Analysis of Synthetic FHIT-Derived Peptides

The fragile histidine triad (FHIT) protein is a member of the large and ubiquitous histidine triad (HIT) family of proteins. On the basis of genetic evidence, it has been postulated that the FHIT protein may function as tumor suppressor, implying a role for the FHIT protein in carcinogenesis. Recently, Gaudio et al. reported that FHIT binds and delocalizes annexin A4 (ANXA4) from plasma membrane to cytosol in paclitaxel-resistant lung cancer cells, thus restoring their chemosensitivity to the drug. They also identified the smallest protein sequence of the FHIT still interacting with ANXA4, ranging fromposition 7 to 13: QHLIKPS. This short sequence of FHIT protein was not only able to bind ANXA4 but also to hold its target in the cytosol during paclitaxel treatment, thus avoiding ANXA4 translocation to the inner side of the cell membrane. Starting from these results, to obtain much information about structure requirements involved in the interaction of the peptide mentioned above, we synthetized a panel of seven peptides through an Ala-scan approach. In detail, to study the binding of FHIT derived peptides with ANXA4, we applied a combination of different biophysical techniques such as differential scanning fluorimetry (DSF), surface plasmon resonance (SPR), and microscale thermophoresis (MST). Circular dichroism (CD) and nuclear magnetic resonance (NMR) were used to determine the conformational structure of the lead peptide (7–13) and peptides generated from ala-scan technique. The application of different biophysical and structural techniques, integrated by a preliminary biological evaluation, allowed us to build a solid structure activity relationship on the synthesized peptides

Synthesis and cytotoxic activity evaluation of 2,3-thiazolidin-4-one derivatives on human breast cancer cell lines

It is well known that resveratrol (RSV) displayed cancer-preventing and anticancer properties but its clinical application is limited because of a low bioavailability and a rapid clearance from the circulation. Aim of this work was to synthesize pharmacologically active resveratrol analogs with an enhanced structural rigidity and bioavailability. In particular, we have synthesized a library of 2,3-thiazolidin-4-one derivatives in which a thiazolidinone nucleus connects two aromatic rings. Some of these compounds showed strong inhibitory effects on breast cancer cell growth. Our results indicate that some of thiazolidin-based resveratrol derivatives may become a new potent alternative tool for the treatment of human breast cancer

A Novel Vasoactive Peptide “PG1” from Buffalo Ice-Cream Protects from Angiotensin-Evoked High Blood Pressure

Arterial hypertension is the most important risk factor for cardiovascular diseases, myocardial infarction, heart failure, renal failure and peripheral vascular disease. In the last decade, milk-derived bioactive peptides have attracted attention for their beneficial cardiovascular properties. Methods: Here, we combined in vitro chemical assay such as LC-MS/MS analysis of buffalo ice cream, ex vivo vascular studies evaluating endothelial and smooth muscle responses using pressure myograph, and translational assay testing in vivo the vascular actions of PG1 administration in murine models. Results: We demonstrate that a novel buffalo ice-cream-derived pentapeptide “QKEPM”, namely PG1, is a stable peptide that can be obtained at higher concentration after gastro-intestinal digestions (GID) of buffalo ice-cream (BIC). It owns potent vascular effect in counteract the effects of angiotensin II-evoked vasoconstriction and high blood pressure levels. Its effects are mediated by the inhibitory effect on AT1 receptor leading to a downregulation of p-ERK½/Rac1-GTP and consequent reduction of oxidative stress. Conclusions: These results strongly candidate PG1, as a novel bioactive peptide for the prevention and management of hypertension, thus expanding the armamentarium of preventive strategies aimed at reducing the incidence and progression of hypertension and its related cardiovascular complication

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe