Structure of Hierridin C, Synthesis of Hierridins B and C, and Evidence for Prevalent Alkylresorcinol Biosynthesis in Picocyanobacteria.

Small, single-celled planktonic cyanobacteria are ubiquitous in the world's oceans yet tend not to be perceived as secondary metabolite-rich organisms. Here we report the isolation and structure elucidation of hierridin C, a minor metabolite obtained from the cultured picocyanobacterium Cyanobium sp. LEGE 06113. We describe a simple, straightforward synthetic route to the scarcely produced hierridins that relies on a key regioselective halogenation step. In addition, we show that these compounds originate from a type III PKS pathway and that similar biosynthetic gene clusters are found in a variety of bacterial genomes, most notably those of the globally distributed picocyanobacteria genera Prochlorococcus, Cyanobium and Synechococcus.

Gemcitabine anti-proliferative activity significantly enhanced upon conjugation with cell-penetrating peptides.

Gemcitabine proven efficiency against a wide range of solid tumors and undergoes deamination to its inactive uridine metabolite, which underlies its low bioavailability, and tumour resistance was also associated with nucleoside transporter alterations. Hence, we have conjugated gemcitabine to cell-penetrating peptides (CPP), in an effort to both mask its aniline moiety and facilitate its delivery into cancer cells. Two CPP-drug conjugates have been synthesized and studied regarding both the time-dependent kinetics of gemcitabine release and their anti-proliferative activity on three different human cancer cell lines. Results obtained reveal a dramatic increase in the anti-proliferative activity of gemcitabine in vitro, upon conjugation with the CPPs. As such, CPP-gemcitabine conjugates emerge as promising leads for cancer therapy.

Is hypocapnia a risk factor for non-invasive ventilation failure in cardiogenic acute pulmonary edema?

INTRODUCTION AND PURPOSE: The impact of hypocapnia in the prognosis of cardiogenic acute pulmonary edema (CAPE) has not been sufficiently studied. The aim of this study was to analyse whether hypocapnia is a risk factor for non-invasive ventilation (NIV) failure and hospital mortality, in CAPE patients CAPE. METHODS: Retrospective observational study of all patients with CAPE treated with NIV. Patients were classified in three groups according to PaCO2 level (hypocapnic, eucapnic and hypercapnic). NIV failure was defined as the need for endotracheal intubation and/or death. RESULTS: 1138 patients were analysed, 390 (34.3%) of which had hypocapnia, 186 (16.3%) had normocapnia and 562 (49.4%) had hypercapnia. NIV failure was more frequent in hypocapnic (60 patients, 15.4%) than in eucapnic (16 pacientes, 8.6%) and hypercapnic group (562 pacientes, 10.7%), with statistical significance (p = 0.027), as well as hospital mortality, 73 (18.7%), 19(10.2%) and 83 (14.8%) respectively (p = 0.026). The predicted factors for NIV failure were the presence of do-not-intubate order, complications related to NIV, a lower left ventricular ejection fraction, higher SAPS II and SOFA score and a higher HACOR score at one hour of NIV initiation. CONCLUSIONS: Hypocapnia in patients with CAPE is associated with NIV failure and a greater in-hospital mortality.

Structure/property relationships for the thermotropic behavior of lysine-based amphiphiles: from hexagonal to smectic phases.

Amino acid-derived gemini surfactants arise as a potentially good alternative to the more conventional lipid and synthetic catanionic systems in view of their enhanced interfacial properties, increased chemical stability, and low toxicity. The presence of an amino acid as the polar headgroup allows toxicity reduction, with the simultaneous increase of biodegradability. For these compounds, the establishment of structure/function relationships from the assessment of their basic aggregation properties is therefore of the utmost interest, e.g., in the design of operative self-assembled systems (e.g., liposomes, nanotubes, etc). In this context, the study of the thermal phase behavior of the dry surfactants is a natural, straightforward first step, the more so as thermotropic liquid crystals are also relevant for practical applications. In this work, several lysine-based amphiphiles with a gemini-like configuration have been synthesized, with the amino acid side chain as the spacer group. The molecules are either esters (neutral, with C6-C12 even chains) or sodium carboxylates (anionic, with C6-C12 even chains). Upon increasing the temperature, different crystalline (cr) and liquid-crystalline (lc) phases have been detected and the corresponding thermodynamic and structural parameters determined by a combination of differential scanning calorimetry, polarizing light microscopy and small-angle X-ray scattering. The phase behavior of the amphiphiles is highly dependent on both the chain length and the presence of charge on the headgroup, with significant differences occurring within and between each group of molecules. The C6 and C8 esters form reverse hexagonal cr and lc phases, while C10 and C12 self-assemble into smectic cr and lc structures, with C10 showing also a reverse hexagonal lc phase prior to isotropization. All the carboxylate derivatives form smectic lc phases at high enough temperature prior to isotropization. The rationalization of the phase behavior and phase transition energetics of the compounds has been put forth on the basis of the intermolecular interactions at stake (van der Waals, H-bonding, electrostatic, and packing) and the molecular shape of the amphiphile.

Acylated-naproxen as the surface-active template in the preparation of micro- and nanospherical imprinted xerogels by emulsion techniques.

A strategy based on water-in-oil emulsion for the dispersion of a sol-gel mixture into small droplets was employed with the view of the production of naproxen-imprinted micro- and nanospheres. The procedure, aiming at a surface imprinting process, comprised the synthesis of a naproxen-derived surfactant. The imprinting process occurred at the interface of the emulsions or microemulsions, by the migration of the NAP-surfactant head into the sol-gel drops to leave surficial imprints due mainly to ion-pair interaction with a cationic group contained within the growing sol-gel network. The surface-imprinted microspheric particles exhibited a log-normal size distribution with geometric mean diameter of 3.1µm. A mesoporous texture was found from measurements of the specific surface area (206m(2)/g) and pore diameter (Dp 2nm). Evaluation of the microspheres as packed HPLC stationary phases resulted in the determination of the selectivity factor against ibuprofen (α=2.1), demonstrating the successful imprinting. Chromatographic efficiency, evaluated by the number of theoretical plates (222platescm(-3)), emerged as an outstanding feature among the set of all relatable formats produced before, an advantage intrinsic to the location of the imprinted sites on the surface. The material presented a capacity of 3.2µmolg(-1). Additionally, exploratory work conducted on their nanoscale counterparts resulted in the production of nanospheres in the size order of 10nm providing good indications of a successful imprinting process.

11(th) National Meeting of Organic Chemistry and 4(th) Meeting of Therapeutic Chemistry.

For the first time under the auspices of Sociedade Portuguesa de Química, the competences of two important fields of Chemistry are brought together into a single event, the 11st National Organic Chemistry Meeting and the the 4th National Medicinal Chemistry Meeting, to highlight complementarities and to promote new synergies. Abstracts of plenary lectures, oral communications, and posters presented during the meeting are collected in this report.

Imidazolidin-4-one derivatives of primaquine as novel transmission-blocking antimalarials.

Imidazolidin-4-one derivatives of primaquine were synthesized as potential double prodrugs of the parent drug. The title compounds inhibit the development of the sporogonic cycle of Plasmodium berghei, affecting the appearance of oocysts in the midguts of the mosquitoes. The imidazolidin-4-ones are very stable, both in human plasma and in pH 7.4 buffer, indicating that they are active per se. Thus, imidazolidin-4-ones derived from 8-aminoquinolines represent a new entry in antimalarial structure-activity relationships.

Synthesis of glycylglycine-imprinted silica microspheres through different water-in-oil emulsion techniques.

Sol-gel molecularly imprinted materials (MIMs) are traditionally obtained by grinding and sieving of a monolith formed by bulk polymerization. However, this process has several drawbacks that can be overcome if these materials are synthesized directly in the spherical format. This work aimed at the development of two efficient methods to prepare spherical glycylglycine-templated silica ("whole-imprinted" and surface-imprinted) through a combination of sol-gel and emulsion techniques. The synthesis of the microspheres was optimized regarding emulsion and sol-gel parameters. Imprinting efficiency of the prepared materials was studied by solid phase extraction and flow microcalorimetry. The particles prepared with glycylglycine and functional monomer, in basic medium (using cyclohexane as non-polar continuous medium) presented the highest imprinting factor - 2.5 - and the respective surface-imprinted material presented an imprinting factor of 1.5. The results of flow microcalorimetry confirmed the action of different mechanisms of glycylglycine adsorption: entropically-controlled interactions were present for the "whole-imprinted" material, indicating adsorption inside small imprinted pores; enthalpically-controlled interactions were observed for the surface-imprinted material, a behaviour more compatible with a template/surface-only interaction. Globally, the two approaches allowed for a successful imprinting effect which was more extensive for the "whole-imprinted" material, whereas the surface-imprinting feature confers to the surface-imprinted xerogel advantages regarding mass transfer kinetics. Overall, the spherical particles obtained by both approaches presented characteristics, such as sphericity, mesoporosity, easy/fast accessibility to imprinted sites, important indicators that these materials may be candidates for stationary phases for efficient, selective chromatographic separation.