Exploiting Knowledge on Structure-Activity Relationships for Designing Peptidomimetics of Endogenous Peptides

Synthesis of Enantiopure cis- and trans-Fused Octahydroisoindole-1-Phosphonic Acids from Octahydroisoindolones

Phosphonic analogs of octahydroisoindole-1-carboxylic acids are bicyclic proline derivatives of interest in drug design and enzymatic mechanism studies. Here we report the stereoselective synthesis of the cis- and trans-fused octahydroisoindole system using oxazoloisoindolone lactam and 1,2-cyclohexanedicarboxylic anhydride as advanced chiral precursors, respectively, yielding enantiopure octahydroisoindolone intermediates with the desired stereochemistry at the ring junction. Finally, using these intermediates, the target (1R,3aR,7aS)- and (1R,3aR,7aR)-octahydroisoindole-1-phosphonic acids and their enantiomers were obtained with complete stereocontrol via highly diastereoselective addition of trimethyl phosphite to chiral N-acyliminium ions as the key step.

Hybrid Hydroxyapatite-Metal Complex Materials Derived from Amino Acids and Nucleobases

Calcium phosphates (CaPs) and their substituted derivatives encompass a large number of compounds with a vast presence in nature that have aroused a great interest for decades. In particular, hydroxyapatite (HAp, Ca10(OH)2(PO4)6) is the most abundant CaP mineral and is significant in the biological world, at least in part due to being a major compound in bones and teeth. HAp exhibits excellent properties, such as safety, stability, hardness, biocompatibility, and osteoconductivity, among others. Even some of its drawbacks, such as its fragility, can be redirected thanks to another essential feature: its great versatility. This is based on the compound's tendency to undergo substitutions of its constituent ions and to incorporate or anchor new molecules on its surface and pores. Thus, its affinity for biomolecules makes it an optimal compound for multiple applications, mainly, but not only, in biological and biomedical fields. The present review provides a chemical and structural context to explain the affinity of HAp for biomolecules such as proteins and nucleic acids to generate hybrid materials. A size-dependent criterium of increasing complexity is applied, ranging from amino acids/nucleobases to the corresponding macromolecules. The incorporation of metal ions or metal complexes into these functionalized compounds is also discussed.

Stereocontrolled Synthesis of Phosphoproline Analogues Containing a trans-Fused Octahydroindole Bicyclic System

Herein we report for the first time the diastereoselective synthesis of (2R,3aR,7aS)- and (2S,3aS,7aR)-octahydroindole-2-phosphonic acid (OicP trans-fused stereoisomers) from diethyl (R)- and (S)-phosphopyroglutamate derivative. The key steps of this procedure are the ruthenium tetroxide oxidation of enantiomerically pure diethyl (R)- and (S)-phosphoprolinate obtained through Katritzky's benzotriazole-oxazolidine methodology, a highly diastereoselective successive double 4,5-diallylation of diethyl (R)- and (S)-phosphopyroglutamate with allyl bromide and allyltrimethylsilane with a trans-addition mode, and a ring-closing metathesis with Grubbs' first-generation ruthenium catalyst.

Towards rational computational peptide design

Peptides are prevalent in biology, mediating as many as 40% of protein-protein interactions, and involved in other cellular functions such as transport and signaling. Their ability to bind with high specificity make them promising therapeutical agents with intermediate properties between small molecules and large biologics. Beyond their biological role, peptides can be programmed to self-assembly, and they are already being used for functions as diverse as oligonuclotide delivery, tissue regeneration or as drugs. However, the transient nature of their interactions has limited the number of structures and knowledge of binding affinities available-and their flexible nature has limited the success of computational pipelines that predict the structures and affinities of these molecules. Fortunately, recent advances in experimental and computational pipelines are creating new opportunities for this field. We are starting to see promising predictions of complex structures, thermodynamic and kinetic properties. We believe in the following years this will lead to robust rational peptide design pipelines with success similar to those applied for small molecule drug discovery.