The development of novel, peptide based structures for tissue engineering materials has been widely researched, and its popularity can be attributed to advancements in technological analysis methods. Using principles based on protein structure and organization, this work describes the novel self-assembly of depsipeptides, which incorporate alternating esters within a native peptide backbone. Chapter 1 introduces and reviews peptide mimics for their utility for tissue engineering applications. Chapter 2 describes the methodology in synthesizing and characterization a depsipeptide library using both solution and solid phase methods. Chapter 3 discusses the effects of depsipeptide length, concentration, and sequence within a range of ionic concentrations and pH ranges on the self-assembly of depsipeptides into spherical nanostructures, fibers, or hydrogels. Chapter 4 describes proposed methods to increase the rate of gelation, followed by discussions of biocompatibility studies from other self-assembling peptide and modified-peptide systems in vitro and in vivo. The work described in this dissertation demonstrates that the synthesis and self-assembly of a depsipeptide family which alternates esters into a native peptide backbone does not disrupt the formation of higher order structures. This study illustrates the potential to synthesize a wide range of depsipeptides with variable side chains and hydrophobic character, as understanding these effects on self-assembly is imperative to the development of biomimetic materials for tissue engineering applications. / text

Prof. Dr. Rodrigo Luiz Oliveira Rodrigues Cunha / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência & Tecnologia - Química, 2014. / O presente trabalho consiste na síntese dos fragmentos C1-C4 e C5-C9 do ácido (2S,4E,6R,8S)-8-hidróxi-2,4,6-trimetil-non-4-enóico (1) que corresponde à porção policetídica da Jaspamida e de diversos Geodiamolídeos. A metodologia empregada para a obtenção de tais fragmentos é raramente vista, pois os dois enantiomêros do precursor; o (RS)-2-metil levulinato de metila; são utilizados na síntese de uma mesma molécula. O fragmento C1-C4 foi obtido através de uma resolução cinética enzimática, promovida por lipase de pâncreas de porco com auxílio da adição de Na2SO4 1,6 mol.L-1 baseando-se na série de Hofmeister para elevar o excesso enantiomérico do produto e finalmente através de uma reação de reciclo fornecer o ácido (-)-(S)-2-metil-4-oxopentanóico com excesso enantiomérico >99%. O fragmento C5-C9 foi obtido através redução do enantiômero não hidrolisado, o (R)-2-metil-4-oxopentanoato de metila, originando o (4R,4S)-2-metil-pentan-1,4-diol, que teve seu álcool secundário resolvido através de uma reação de resolução cinética enzimática com o emprego de lipase de Candida antarctica B. / The present work consists in the preparation of fragments C1-C4 and C5-C9 of (2S,4E,6R,8S)-2,4,6-trimethyl-8-hydroxy-non-4-enoic acid (1), that corresponds to polyketide unit of Jaspamide and Geodiamolides. The methodology applied to obtain such fragments is rarely seen, once both fragments of precursor, (RS)-methyl 2-methyl levulinate are used in the synthesis of the same molecule. The fragment C1-C4 was obtained through an enzymatic kinetic resolution promoted by Porcine Pancreas Lipase with assistance of addition of NaSO4 1.6 mol.L-1 based on Hofmeister series to increase the enantiomeric excess of product and finally through a recycle reaction resulting the (-)-(S)-2-methyl-4-oxopentanoic acid with enantiomeric excess >99%, the fragment C1-C4. The fragment C5-C9 was obtained through a reduction of the enantiomer not hydrolyzed, (R)-methyl-2-metil-4-oxopentanoate, affording a diastereomeric mixture of (2R)-methylpentan-1,4-diol, that had the secondary alcohol resolved through a reaction of kinetic enzymatic resolution with employment of Candida antarctica lipase B.