Modification of polyhenols by glucosylation using GH13 glycosidases and acylation with lipases, and its effect on physicochemical and bioactive properties

• Autores: José Luís González Alfonso
• Directores de la Tesis: Francisco José Plou Gasca (dir. tes.), Antonio Ballesteros Olmo (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2022
• Idioma: inglés
• Número de páginas: 192
• Títulos paralelos:
  • Modificación de polifenoles por glucosilación con glicosidasas GH13 y acilación con lipasas, y su efecto en sus propiedades físicoquímicas y bioactivas
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Polyphenols from vegetable origin are becoming very important in the last years because of their ability to prevent diseases such as cancer, arthritis, Alzheimer's disease, Parkinson's or even cellular aging. These diseases are related to the presence of free radicals and oxygen species, which can cause damage to the DNA, proteins and lipids of the cells. For this reason, the intake of polyphenols can help to prevent cellular damage due to their extraordinary antioxidant capacity. However, their low aqueous solubility, limited stability and/or rapid metabolization cause to these compounds a low bioavailability. These properties can be modulated through glycosylation and/or acylation of polyphenols. This thesis describes the synthesis of glucosides from various natural polyphenols with interesting biological properties: epigallocatechin gallate (EGCG), pterostilbene, hesperetin, rutin, phloretin and hydroxytyrosol. For this propose, enzymes belonging to family GH13 of glucosylhydrolases with transglycosylating activity have been employed. Specifically, cyclodextrin glucosyltransferases (CGTases) from different microorganisms and a mutant of the sucrose phosphorylase (TtSPP_R134A) from Thermoanaerobacterium thermosaccharolyticum.

    The ability of CGTases to glucosylate tertiary alcohols was also demonstrated, obtaining tert- butyl glucosides with surfactant properties. It was necessary the development of chromatographic methods (HPLC and TLC) to follow the reactions and study their progress. The reaction conditions were also optimized employing different ratios sugar donor/acceptor, cosolvents, and pHs. Once the reaction conditions were optimized, the products were purified by semipreparative HPLC or silica-gel chromatographic columns, and characterized by MS and 2D-NMR. On the other hand, the regioselectivity of the lipase from Thermomyces lanuginosus to acylate at 6-OH glucose position has allowed the obtention of lauric esters (C12) of phloretin and EGCG after their glucosylation. The reactions were followed by HPLC and TLC, and the products were purified. The molecular structure of the obtained acyl-glucosides were determined by MS and NMR.

    Finally, studies of stability, solubility, cell viability, antioxidant activity and percutaneous absorption of some of the synthesized derivatives have been carried out in order to evaluate how these properties change after glycosylation and / or acylation