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Fenretinide (4-HPR) is a synthetic retinoid which has been investigated for decades as an anticancer agent and more recently as a potential drug to treat metabolic syndrome. Here we synthesised a library of 4-HPR analogues - using a SAR approach - with the final goal to improve both anti-cancer activity and anti- obesity/diabetes properties of 4-HPR. Among the designed 4-HPR analogues, we selected the click-type analogue 3b, which is amenable to radiofluorination, to develop a PET tracer to further investigate the pharmacological profile of 4-HPR and analogues in vivo.

Paolo Lazzari,1 Marco Spiga,1 Monica Sani,1,2 Matteo Zanda,2,3 Ian N Fleming4 1KemoTech s.r.l., Parco Scientifico della Sardegna, Pula, Cagliari, 2C.N.R. – Istituto di Chimica del Riconoscimento Molecolare, Sezione ‘A. Quilico’, Milano, Italy; 3Kosterlitz Centre for Therapeutics, Institute of Medical Sciences, University of Aberdeen, 4Aberdeen Biomedical Imaging Centre, Institute of Medical Sciences, Foresterhill, Aberdeen, Scotland, UK Purpose: There is an urgent need to develop effective therapies and treatment strategies to treat hypoxic tumors, which have a very poor prognosis and do not respond well to existing therapies.Methods: A novel hypoxia-targeting agent, KEMTUB012-NI2, was synthesized by conjugating a 2-nitroimidazole hypoxia-targeting moiety to a synthetic tubulysin, a very potent antimitotic. Its hypoxic selectivity and mode of action were studied in breast cancer cell lines.Results: KEMTUB012-NI2 exhibited a similar selectivity for hypoxic cells to that of tirapazamine, a well-established hypoxia-targeting agent, but was >1,000 times more potent in cell cytotoxicity assays. The hypoxia-targeting mechanism for both KEMTUB012-NI2 and tirapazamine was selective and mediated by one-electron reductases. However, while cytochrome p450 reductase (POR) downregulation could inhibit tirapazamine cytotoxicity, it actually sensitized hypoxic cells to KEMTUB012-NI2.Conclusion: KEMTUB012-NI2 is a potent new agent that can selectively target hypoxic cancer cells. The hypoxia selectivity of KEMTUB012-NI2 and tirapazamine appears to be differentially activated by reductases. Since reductases are heterogeneously expressed in tumors, the different activation mechanisms will allow these agents to complement each other. Combining POR downregulation with KEMTUB012-NI2 treatment could be a new treatment strategy that maximizes efficacy toward hypoxic tumor cells while limiting systemic toxicity. Keywords: breast cancer, tubulysin, anti-mitotic, hypoxia, cell death, reductase

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Hyperpolarization enhances the intensity of the NMR signals of a molecule, whose in vivo metabolic fate can be monitored by MRI with higher sensitivity. SABRE is a hyperpolarization technique that could potentially be used to image nitric oxide (NO) production in vivo. This would be very important, because NO dysregulation is involved in several pathologies, including cardiovascular ones. The nitric oxide synthase (NOS) pathway leads to NO production via conversion of L-arginine into L-citrulline. NO is a free radical gas with a short half-life in vivo (approximate to 5 s), therefore direct NO quantification is challenging. An indirect method - based on quantifying conversion of an L-Arg - to L-Cit-derivative by H-1 NMR spectroscopy is herein proposed. A small library of pyridyl containing L-Arg derivatives was designed and synthesised. In vitro tests showed that compounds 4a-j and 11a-c were better or equivalent substrates for the eNOS enzyme (NO2- production = 19-46 uM) than native L-Arg (NO2- production = 25 mu M). Enzymatic conversion of L-Arg to L-Cit derivatives could be monitored by 1H NMR. The maximum hyperpolarization achieved by SABRE reached 870-fold NMR signal enhancement, which opens up exciting future perspectives of using these molecules as hyperpolarized MRI tracers in vivo. (C) 2017 The Authors. Published by Elsevier Ltd.

Psi[CH(CF3)NH]Gly peptides, a conceptually new class of peptidomimetics having a stereogenic trifluoroethylamine group as a natural peptide-bond surrogate, have been synthesized by stereoselective addition of alpha-amino acid esters to trans-3,3,3-trifluoro-1-nitropropene. Long range nuclear Overhauser effects, detected via ROESY experiments, provided evidence that model Psi[CH(CF3)NH]Glytetrapeptides incorporating a trifluoroethylamine mimic of the dipeptide loop Pro-Gly can be represented by an ensemble of unfolded and folded conformations. The latter are driven by the formation of a hydrogen bond between a carbonyl group and the aminic proton of the trifluoroethylamine unit. MD calculations indicate a population of conformers which adopt folded beta turn structures for all the L-peptides; on the other hand, a D-stereochemistry at the Pro residue induces a natural folding towards a beta hairpin conformation driven by the formation of a second hydrogen bond, regardless of the stereochemistry of the stereogenic peptide bond surrogate.

Triazines functionalized with three stereogenic alpha-amino-acidic appendages having at least one amide or hydroxamate function give highly stable organogels in haloalkanes and aromatic solvents, and their gelating ability depends on both structural and stereochemical properties.

Earlier analysis of the Italian population showed patterns of genetic differentiation that were interpreted as being the result of population settlements going back to pre-Roman times. DNA disease mutations may be a powerful tool in further testing this hypothesis since the analysis of diseased individuals can detect variants too rare to be resolved in normal individuals. We present data on the relative frequencies of 60 cystic fibrosis (CF) mutations in Italy and the geographical distribution of the 12 most frequent CF mutations screened in 3492 CF chromosomes originating in 13 Italian regions. The 12 most frequent mutations characterize about 73% of the Italian CF chromosomes. The most common mutation, delta F508, has an average frequency of 51%, followed by N1303K and G542X, both with average frequencies around 5%. Multivariate analyses show that the relative frequencies of CF mutations are heterogeneous among Italian regions, and that this heterogeneity is weakly correlated with the geographical pattern of non-DNA 'classical' genetic markers. The northern regions are well differentiated from the central-southern regions and within the former group the western and eastern regions are remarkably distinct. Moreover, Sardinia shows the presence of mutation T338I, which seems absent in any other European CF chromosome. The north-western regions of Italy, characterized by the mutation 1717-1G--A, were under Celtic influence, while the north-east regions, characterized by the mutations R1162X, 2183AA--G and 711 + 5G--A, were under the influence of the Venetic culture.

Human matrix metalloproteinase 9 (MMP-9), also called gelatinase B, is particularly involved in inflammatory processes, bone remodelling and wound healing, but is also implicated in pathological processes such as rheumatoid arthritis, atherosclerosis, tumour growth, and metastasis. We have prepared the inactive E402Q mutant of the truncated catalytic domain of human MMP-9 and co-crystallized it with active site-directed synthetic inhibitors of different binding types. Here, we present the X-ray structures of five MMP-9 complexes with gelatinase-specific, tight binding inhibitors: a phosphinic acid (AM-409), a pyrimidine-2,4,6-trione (RO-206-0222), two carboxylate (An-1 and MJ-24), and a trifluoromethyl hydroxamic acid inhibitor (MS-560). These compounds bind by making a compromise between optimal coordination of the catalytic zinc, favourable hydrogen bond formation in the active-site cleft, and accommodation of their large hydrophobic P1' groups in the slightly flexible S1 cavity, which exhibits distinct rotational conformations of the Pro421 carbonyl group in each complex. In all these structures, the side-chain of Arg424 located at the bottom of the S1' cavity is not defined in the electron density beyond C-gamma, indicating its mobility. However, we suggest that the mobile Arg424 side-chain partially blocks the S1' cavity, which might explain the weaker binding of most inhibitors with a long P1' side-chain for MMP-9 compared with the closely related MMP-2 (gelatinase A), which exhibits a short threonine side-chain at the equivalent position. These novel structural details should facilitate the design of more selective MMP-9 inhibitors.