RESUMEN
Rutin and esculin were enzymatically acylated with different aliphatic acids as acyl donors (fatty acids, dicarboxylic acids and omega-substituted fatty acids) by an immobilized lipase from Candida antarctica. The effect of the water content and the acyl donors pattern on the flavonoid initial acylation rate and conversion yield were investigated. The obtained results indicated that the water content of the medium has a strong effect on the performance of these reactions. The best conversion yields were reached when the water content was kept lower than 200 ppm. At low water content of the medium, these syntheses are influenced by carbon chain length and substitution pattern of the acyl donors. Higher conversion yields of esculin and rutin (>70%) were obtained with aliphatic acids having high carbon chain length (>12). Moreover, it has been found that the amine and thiol groups on omega-substituted fatty acid chain were unfavourable to these reactions. The 1H NMR and 13C NMR analyses of some synthesized esters (esculin and rutin palmitate) show that only monoesters were produced and that the esterification takes place on the primary OH of glucose moiety of the esculin and on the secondary 4"'-OH of the rhamnose residue of rutin.
Asunto(s)
Flavonoides/química , Flavonoides/metabolismo , Acilación , Candida/enzimología , Isótopos de Carbono , Catálisis , Ácidos Dicarboxílicos/química , Ácidos Dicarboxílicos/metabolismo , Esculina/metabolismo , Esterificación , Ésteres/síntesis química , Ácidos Grasos/química , Ácidos Grasos/metabolismo , Estudios de Factibilidad , Interacciones Hidrofóbicas e Hidrofílicas , Cinética , Lipasa/química , Lipasa/metabolismo , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Protones , Rutina/biosíntesis , Especificidad por Sustrato , Agua/químicaRESUMEN
Epoxide hydrolase activity was produced during the exponential and stationary growth phases of the fungus Beauveria bassiana ATCC 7159. It was completely cell-associated. After cell disruption epoxide hydrolase activity was recovered in both the cell debris (EH "A") and the soluble fraction (EH "B"), but not in the membrane fraction. Activity assays of these fractions with two different substrates indicated that their substrate specificity, as well as the corresponding E value and, to a lesser extent, their regioselectivity, were different. Also, we could observe that the absolute configuration of the residual epoxide was opposite. This indicates that these two epoxide hydrolase activities are substantially different and are, therefore, interestingly complementary biocatalysts for the preparation of the corresponding epoxides and/or vicinal diols in nearly enantiopure form.