New marine cytotoxic bispyrones : absolute sterochemistry of onchitriols I and II

The complete absolute stereochemistry of two new cytotoxic marine polyproniates isolated from the saponified extract of the pulmonate mollusc #Onchidium sp.$, onchitriol 1 and 2 (4,5), was established using Mosher-Trost's methodollogy. (Résumé d'auteur

Click Chemistry with Polymers, Dendrimers, and Hydrogels for Drug Delivery

This is a post-peer-review, pre-copyedit version of an article published in Pharmaceutical Research. The final authenticated version is available online at: https://doi.org/10.1007/s11095-012-0683-yDuring the last decades, great efforts have been devoted to design polymers for reducing the toxicity, increasing the absorption, and improving the release profile of drugs. Advantage has been also taken from the inherent multivalency of polymers and dendrimers for the incorporation of diverse functional molecules of interest in targeting and diagnosis. In addition, polymeric hydrogels with the ability to encapsulate drugs and cells have been developed for drug delivery and tissue engineering applications. In the long road to this successful story, pharmaceutical sciences have been accompanied by parallel advances in synthetic methodologies allowing the preparation of precise polymeric materials with enhanced properties. In this context, the introduction of the click concept by Sharpless and coworkers in 2001 focusing the attention on modularity and orthogonality has greatly benefited polymer synthesis, an area where reaction efficiency and product purity are significantly challenged. The purpose of this Expert Review is to discuss the impact of click chemistry in the preparation and functionalization of polymers, dendrimers, and hydrogels of interest in drug deliveryThis work was financially supported by the Spanish Ministry of Science and Innovation (CTQ2009-10963 and CTQ2009-14146-C02-02) and the Xunta de Galicia (10CSA209021PR and CN2011/037)S

The Natriuretic Peptide Uroguanylin Elicits Physiologic Actions Through 2 Distinct Topoisomers

The peptide uroguanylin regulates electrolyte transport in the intestine and kidney. Human uroguanylin has two conformations that can be stably isolated, owing to their slow interconversion rate. The A isomer potently activates the guanylate cyclase-C receptor found primarily in the intestine. The B isomer, by contrast, is a very weak agonist of this receptor, leading to a widely-held assumption that it is physiologically irrelevant. We show here, however, that human uroguanylin B has potent natriuretic activity in the kidney. Interestingly, uroguanylin A and B both induce saliuretic responses, but the activity profiles for the two peptides differ markedly. The uroguanylin B dose-response curve is sigmoidal with a threshold dose near 10 nmol/kg body weight, whereas uroguanylin A has a comparable threshold, but a bell-shaped dose-response curve. Additionally, our study indicates a unique interplay between the A and B isoforms, such that the A form at high concentrations antagonizes the natriuretic action of the B form. These data show that the kidney contains a uroguanylin receptor whose pharmacological profile does not match that of the well-defined intestinal uroguanylin receptor (guanylate cyclase-C), an observation consistent with previous studies showing that the kidney of the guanylate cyclase-C knockout mouse remains responsive to uroguanylin. The results presented here also support the unconventional notion that distinct conformations of a single endocrine peptide can elicit different responses in different tissues