Thio-conjugation of substituted benzofurazans to peptides: molecular sieves catalyze nucleophilic attack on unsaturated fused rings

Bioconjugates of 2,1,3-benzoxadiazole (benzofurazan) and its derivatives have attracted considerable interest due to their biological activities and applications as fluorescent tags. A high-yield, chemoselective, and mild procedure for the S-alkylation of cysteine containing peptides by benzofurazan halogenides is reported. The key feature of this procedure is the use of activated molecular sieves (MS) to catalyze thiol activation for nucleophilic substitution under very mild conditions (room temperature and no need for added bases). To the best of our knowledge, this is the first report about thiol nucleophilic substitution performed on unsaturated and annelated systems catalyzed by activated molecular sieves. Reaction yields were remarkable even with benzofurazans having weakly activating groups or no activating groups at all. The potential of the new methodology was explored by synthesizing fluorescent, hydrophilic benzofurazan/peptide conjugates, also with peptides containing unprotected lysine residues

Reactivity of S- or Se- containing model peptides with environmental relevant Hg ions: LC-MS/MS study

Selenium (Se) is an essential element being present in the form of the naturally occurring amino acid selenocysteine (Sec), 25 human proteins involved in different cellular pathways contain Sec. As the most potent intracellular soft Lewis base, selenocysteine (SeCys) is able to bind electron poor soft acids as heavy metals, of awareness for environmental and human toxicology, Hg ions bind Se by means of higher equilibrium constants than sulfur (ca. 106 times), therefore these values compensate the lower cellular abundance (105 times) of selenols compared to thiols[2]. In this communication we present a comparative reactivity study of Hg(I) and Hg(II) compounds with model peptides: vasopressin (AVP) hormone with antidiuretic and vasopressor actions and its Sec containing analogs. These peptides were synthesized either by standard solid phase peptide Fmoc or Boc protocols. The metal ion interaction with these peptides was investigated by RP- LC coupled with electrospray MS/MS detection (LC-MS/MS). We observed mono, bis and bridged peptide metallations as detailed in the Scheme. Taking into consideration the stability of Se-Hg bonds, our results support the hypothesis of a binding preference of Hg to Sec residues in selenoproteins

γ sulphate PNA (PNA S): Highly Selective DNA Binding Molecule Showing Promising Antigene Activity

Peptide Nucleic Acids (PNAs), nucleic acid analogues showing high stability to enzyme degradation and strong affinity and specificity of binding toward DNA and RNA are widely investigated as tools to interfere in gene expression. Several studies have been focused on PNA analogues with modifications on the backbone and bases in the attempt to overcome solubility, uptake and aggregation issues. γ PNAs, PNA derivatives having a substituent in the γ position of the backbone show interesting properties in terms of secondary structure and affinity of binding toward complementary nucleic acids. In this paper we illustrate our results obtained on new analogues, bearing a sulphate in the γ position of the backbone, developed to be more DNA-like in terms of polarity and charge. The synthesis of monomers and oligomers is described. NMR studies on the conformational properties of monomers and studies on the secondary structure of single strands and triplexes are reported. Furthermore the hybrid stability and the effect of mismatches on the stability have also been investigated. Finally, the ability of the new analogue to work as antigene, interfering with the transcription of the ErbB2 gene on a human cell line overexpressing ErbB2 (SKBR3), assessed by FACS and qPCR, is described

A Late-Stage Synthetic Approach to Lanthionine-Containing Peptides via S-Alkylation on Cyclic Sulfamidates Promoted by Molecular Sieves

A one-pot, high-yield procedure for synthesizing lanthionine-containing peptides was developed. It relies on the S-alkylation of cysteine-containing peptides with chiral cyclic sulfamidates. The key feature of this approach is the use of mild reaction conditions (only activated molecular sieves are employed as the catalyst), leading to good chemoselectivity and excellent stereochemical control. The potential of the new methodology has been investigated by synthesizing the thioether ring of a natural lantibiotic, Haloduracin \u3b2

Acylpeptide Hydrolase Inhibition as Targeted Strategy to Induce Proteasomal Down-Regulation

Acylpeptide hydrolase (APEH), one of the four members of the prolyl oligopeptidase class, catalyses the removal of N-acylated amino acids from acetylated peptides and it has been postulated to play a key role in protein degradation machinery. Disruption of protein turnover has been established as an effective strategy to down-regulate the ubiquitin-proteasome system (UPS) and as a promising approach in anticancer therapy

Silver (I) N-Heterocyclic Carbene Complexes: A Winning and Broad Spectrum of Antimicrobial Properties

The evolution of antibacterial resistance has arisen as the main downside in fighting bacterial infections pushing researchers to develop novel, more potent and multimodal alternative drugs.Silver and its complexes have long been used as antimicrobial agents in medicine due to the lack of silver resistance and the effectiveness at low concentration as well as to their low toxicities compared to the most commonly used antibiotics. N-Heterocyclic Carbenes (NHCs) have been extensively employed to coordinate transition metals mainly for catalytic chemistry. However, more recently, NHC ligands have been applied as carrier molecules for metals in anticancer applications. In the present study we selected from literature two NHC-carbene based on acridinescaffoldand detailed nonclassicalpyrazole derived mono NHC-Ag neutral and bis NHC-Ag cationic complexes. Their inhibitor effect on bacterial strains Gram-negative and positivewas evaluated. Imidazolium NHC silver complex containing the acridine chromophore showed effectiveness at extremely low MIC values. Although pyrazole NHC silver complexes are less active than the acridine NHC-silver, they represent the first example of this class of compounds with antimicrobial properties. Moreover all complexesare not toxic and they show not significant activity againstmammalian cells (Hek lines) after 4 and 24 h. Based on our experimental evidence, we are confident that this promising class of complexes could represent a valuable starting point for developing candidates for the treatment of bacterial infections, delivering great effectiveness and avoiding the development of resistance mechanisms

Evaluation of the anti-angiogenic properties of the new selective αVβ3 integrin antagonist RGDechiHCit

Integrins are heterodimeric receptors that play a critical role in cell-cell and cell-matrix adhesion processes. Among them, αVβ3 integrin, that recognizes the aminoacidic RGD triad, is reported to be involved in angiogenesis, tissue repair and tumor growth. We have recently synthesized a new and selective ligand of αVβ3 receptor, referred to as RGDechiHCit, that contains a cyclic RGD motif and two echistatin moieties.The aim of this study is to evaluate in vitro and in vivo the effects of RGDechiHCit. Therefore, we assessed its properties in cellular (endothelial cells [EC], and vascular smooth muscle cells [VSMC]) and animal models (Wistar Kyoto rats and c57Bl/6 mice) of angiogenesis.In EC, but not VSMC, RGDechiHCit inhibits intracellular mitogenic signaling and cell proliferation. Furthermore, RGDechiHCit blocks the ability of EC to form tubes on Matrigel. In vivo, wound healing is delayed in presence of RGDechiHCit. Similarly, Matrigel plugs demonstrate an antiangiogenic effect of RGDechiHCit.Our data indicate the importance of RGDechiHCit in the selective inhibition of endothelial αVβ3 integrin in vitro and in vivo. Such inhibition opens new fields of investigation on the mechanisms of angiogenesis, offering clinical implications for treatment of pathophysiological conditions such as cancer, proliferative retinopathy and inflammatory disease

Crystallization and preliminary X-ray diffraction studies of a D

A 10-mer duplex formed between a PNA containing a `chiral box' of three adjacent d-Lys-based monomers and its complementary DNA strand has been crystallized for the first time. Crystals have been obtained using PEG 8000 as precipitant and cacodylate at pH 6.3 as buffer. The crystals belong to the space group P31 or to its enantiomorph P32, with unit-cell parameters a = b = 35.00, c = 35.91 Å. A complete data set has been collected at the synchrotron source Elettra in Trieste to 1.85 Å resolution, using a single frozen crystal

Lock, Stock and Barrel: Role of Renin-Angiotensin-Aldosterone System in Coronavirus Disease 2019

none16noSince the end of 2019, the medical-scientific community has been facing a terrible pandemic caused by a new airborne viral agent known as SARS-CoV2. Already in the early stages of the pandemic, following the discovery that the virus uses the ACE2 cell receptor as a molecular target to infect the cells of our body, it was hypothesized that the renin-angiotensin-aldosterone system was involved in the pathogenesis of the disease. Since then, numerous studies have been published on the subject, but the exact role of the renin-angiotensin-aldosterone system in the pathogenesis of COVID-19 is still a matter of debate. RAAS represents an important protagonist in the pathogenesis of COVID-19, providing the virus with the receptor of entry into host cells and determining its organotropism. Furthermore, following infection, the virus is able to cause an increase in plasma ACE2 activity, compromising the normal function of the RAAS. This dysfunction could contribute to the establishment of the thrombo-inflammatory state characteristic of severe forms of COVID-19. Drugs targeting RAAS represent promising therapeutic options for COVID-19 sufferers.openZanza, Christian; Tassi, Michele Fidel; Romenskaya, Tatsiana; Piccolella, Fabio; Abenavoli, Ludovico; Franceschi, Francesco; Piccioni, Andrea; Ojetti, Veronica; Saviano, Angela; Canonico, Barbara; Montanari, Mariele; Zamai, Loris; Artico, Marco; Robba, Chiara; Racca, Fabrizio; Longhitano, YaroslavaZanza, Christian; Tassi, Michele Fidel; Romenskaya, Tatsiana; Piccolella, Fabio; Abenavoli, Ludovico; Franceschi, Francesco; Piccioni, Andrea; Ojetti, Veronica; Saviano, Angela; Canonico, Barbara; Montanari, Mariele; Zamai, Loris; Artico, Marco; Robba, Chiara; Racca, Fabrizio; Longhitano, Yaroslav

High-Resolution Conformational Analysis of RGDechi-Derived Peptides Based on a Combination of NMR Spectroscopy and MD Simulations

The crucial role of integrin in pathological processes such as tumor progression and metastasis formation has inspired intense efforts to design novel pharmaceutical agents modulating integrin functions in order to provide new tools for potential therapies. In the past decade, we have investigated the biological proprieties of the chimeric peptide RGDechi, containing a cyclic RGD motif linked to an echistatin C-terminal fragment, able to specifically recognize αvβ3 without cross reacting with αvβ5 and αIIbβ3 integrin. Additionally, we have demonstrated using two RGDechi-derived peptides, called RGDechi1-14 and ψRGDechi, that chemical modifications introduced in the C-terminal part of the peptide alter or abolish the binding to the αvβ3 integrin. Here, to shed light on the structural and dynamical determinants involved in the integrin recognition mechanism, we investigate the effects of the chemical modifications by exploring the conformational space sampled by RGDechi1-14 and ψRGDechi using an integrated natural-abundance NMR/MD approach. Our data demonstrate that the flexibility of the RGD-containing cycle is driven by the echistatin C-terminal region of the RGDechi peptide through a coupling mechanism between the N- and C-terminal regions