INQUISUR   21779
INSTITUTO DE QUIMICA DEL SUR
Unidad Ejecutora - UE
capítulos de libros
Título:
Alkyl Esters of L-Ascorbic Acid: From Synthesis to Applications
Autor/es:
BENEDINI LUCIANO; FANANI LAURA ; VICO RAQUEL
Libro:
Ascorbic Acid: Properties, Synthesis and Applications
Editorial:
NOVA Science
Referencias:
Lugar: New York; Año: 2016; p. 141 - 174
Resumen:
AbstractAntioxidants are importantadditives in food, cosmetics and pharmaceutics, and vitamin C being one of thebest positioned for industrial applications. The usage of native L-ascorbicacid is limited to water containing media because its hydrophilic nature. Toovercome this issue an extensive effort has been made to develop newamphiphilic derivatives capable to be applied in lipophilic environments.  The alkyl derivatives obtained throughesterification of the primary hydroxyl group of L-ascorbic acid with differentreagents are the most widely studied compounds from the synthetic,physicochemical and pharmaceutical point of view as well as are those most usedin commercial formulations. This book chapter offers acomprehensive revision of the bibliography regarding the main pathways tosynthesize these alkyl derivatives, involving enzyme catalysis andesterification in acidic or alkaline media to obtain the alkanoyl-6-O-ascorbic acid esters (ASCn). Thisinformation is presented together with their stability properties. Besides its antioxidantproperties, the ASCn family has been used in different pharmacologicalpreparations per its amphiphilic nature. The presence of the acyl chainprovides the capacity to self-organize into micelles and coagel when suspendedin water. The knowledge of the phase behaviour of surfactants in aqueous mediais relevant for the understanding of the properties of these systems and isvital for the numerous industrial applications. These, along with a revision ofsurface properties of the ASCn family are developed in this chapter. The ASCn amphiphiles, when self-organized at theair-water interface form Gibbs and Langmuir monolayers with a large variety ofstability, phase states and surface textures depending on the length of theacyl chain moiety and ionization conditions. Furthermore, the different membersof ASCn family have some differences in its effectiveness for determinedpharmaceutical purposes. Then,the physicochemical properties of each member of thisdrug family may be determinant for their efficacy in those pharmaceuticalprocesses, in particular those related to surface phenomena and interactionwith biomembranes. Cell membranes are the first contact of lipophilicdrugs with cells and often form a reservoir. Then, the drug/membrane interactionis a fundamental condition for its pharmacological function and a potentialregulatory point. Here are revised some attempts made to experimentally explorethe interaction and general physicochemical effect of the ASCn family memberswhen they are incorporated into model lipid membranes under controlled conditions.Finally, some approaches in the use of ASCn inbiomedicine were revised. Those attempts were based mainly on I) theirantioxidant capability because the presence of ASCn derivatives in formulationscould prevent degradation of drugs sensitive to light exposure, oxidizing orreactive oxygen compounds and/or II) the capacity of ASCn to form micelles,coagels and liquid crystals, which can modify some properties of the medium andact as drug delivery nanostructures. The new strategies in the use of ASCncomprise examples from liposome-based encapsulated nanoparticles to noveladjuvant activity of ASCn liquid crystals with high immunological efficiency.