Macrocyclization of Peptide Side Chains by the Ugi Reaction: Achieving Peptide Folding and Exocyclic N-Functionalization in One Shot.

The cyclization of peptide side chains has been traditionally used to either induce or stabilize secondary structures (β-strands, helices, reverse turns) in short peptide sequences. So far, classic peptide coupling, nucleophilic substitution, olefin metathesis, and click reactions have been the methods of choice to fold synthetic peptides by means of macrocyclization. This article describes the utilization of the Ugi reaction for the side chain-to-side chain and side chain-to-termini macrocyclization of peptides, thus enabling not only access to stable folded structures but also the incorporation of exocyclic functionalities as N-substituents.

Aminocatalysis-Mediated on-Resin Ugi Reactions: Application in the Solid-Phase Synthesis of N-Substituted and Tetrazolo Lipopeptides and Peptidosteroids.

A new solid-phase protocol for the synthesis of N-substituted and tetrazolo peptides is described. The strategy relies on the combination of aminocatalysis-mediated on-resin Ugi reactions and peptide couplings for the N-alkylation of peptides at selected sites, including the N-terminal double lipidation, the simultaneous lipidation/biotinylation, and the steroid/lipid conjugation via tetrazole ring formation. The solid-phase Ugi four-component reactions were enabled by on-resin transimination steps prior to addition of the acid and isocyanide components.

A multiple multicomponent approach to chimeric peptide-peptoid podands.

The success of multi-armed, peptide-based receptors in supramolecular chemistry traditionally is not only based on the sequence but equally on an appropriate positioning of various peptidic chains to create a multivalent array of binding elements. As a faster, more versatile and alternative access toward (pseudo)peptidic receptors, a new approach based on multiple Ugi four-component reactions (Ugi-4CR) is proposed as a means of simultaneously incorporating several binding and catalytic elements into organizing scaffolds. By employing α-amino acids either as the amino or acid components of the Ugi-4CRs, this multiple multicomponent process allows for the one-pot assembly of podands bearing chimeric peptide-peptoid chains as appended arms.

Coronary artery disease in patients with rheumatic and non-rheumatic valvular heart disease treated at a public hospital in Rio de Janeiro.

Objective: to estimate the prevalence of coronary artery disease (CAD) in valvular heart disease of rheumatic (RVHD) and non-rheumatic (NVHD) etiology, assessing possible predictive factors for the presence of CAD.

Methods: This is a cross-sectional study of a series of cases obtained from a pre-defined population, wherein 1,412 patients referred for heart surgery of any etiology were evaluated. Of these, 294 primary heart disease patients aged > or =40 submitted to cinecoronary arteriography (CA) were identified and studied.