Effect of ionic liquids on enzymatic synthesis of caffeic acid phenethyl ester

Abstract

Although caffeic acid phenethyl ester (CAPE), an active flavonoid, plays an important role in the antioxidant activity of honeybee propolis, the isolation of CAPE from honeybee propolis is time-consuming due to wide variety of impurities present. Therefore, biochemical method to synthesize CAPE was investigated in this study. Since ionic liquids (ILs) possess some unique characteristics as appreciated alternatives to conventional solvents for certain biotransformation, the effect of ILs as reaction media for enzymatic synthesis of CAPE was assessed. Several factors including substrate molar ratio, and reaction temperature affecting the conversion yield of lipase-catalyzed CAPE synthesis were also investigated. Reaction yields were significantly higher in hydrophobic ILs than in hydrophilic ILs (almost zero). Among nine hydrophobic ILs tested, the highest conversion of synthetic reaction was obtained in 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][Tf(2)N]). A reaction temperature of 70 °C was found to give high conversion. In addition, optimal substrate molar ratio between phenethyl alcohol and caffeic acid (CA) was decreased significantly from 92:1 to 30:1 when ILs were used instead of isooctane.

Cooperative Reinforcement of Ionic Liquid and Reactive Solvent on Enzymatic Synthesis of Caffeic Acid Phenethyl Ester as an In Vitro Inhibitor of Plant Pathogenic Bacteria

“…Figure 6 B shows the effect of reaction temperature on the yield of CAPE in the biphasic system; an increase in the reaction temperature during the range of 65–75 °C led to an increase of the total CAPE yield until 60 h. This indicated that the increasing of temperature might improve the solubility of MC in [Bmim][Tf 2 N], reduce IL viscosity and decrease mass transfer limitations [ 8 , 11 ]; also, this could strengthen the solubility of CAPE in solvents, accelerate the complexation reaction and promote the equilibrium of complex formation with TOPO. However, with a temperature higher than 75 °C, the total yield notably decreased, most likely due to partial damage on the complex formations between CAPE and TOPO and thermal inactivation of the enzyme.…”

“…However, an aqueous/organic system is not suitable for water-sensitive lipase-catalyzed reactions. Recently, ionic liquids (ILs) have been applied as solvents in lipase-catalyzed reactions to synthetize a myriad of products [ 8 , 9 , 10 ]. It is widely believed that lipases in ILs possess higher activity, stability and selectivity, which can increase the yield of products and the conversion of feedstocks [ 11 ].…”

“…Because CAPE is extraordinarily active, readily degraded or transformed into other by-products, particularly at high temperatures [ 11 ], therefore IL is a “greener” medium instead of conventional solvent and prevented the drawbacks of effumability, lipase inhibition and product instability. Using ILs containing anion [Tf 2 N] − (i.e., 1-ethyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl]imide ([Emim][Tf 2 N]) and 1- n -butyl 3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf 2 N])) as a medium, CA conversion was obtained from 92% [ 8 ] to 98.75% [ 11 ], but the CAPE yield is still only approximately 64.55%. To solve this problem, our preliminary study proposed two schemes: one is to add 2% ( v / v ) DMSO as a co-solvent in the IL to improve the solubility of CA from 4.5 g/L–9 g/L, obtaining a CAPE yield of 79.53% via esterification from CA and PE [ 19 ]; the other is to use a continuous-flow packed-bed microreactor to replace a batch reactor, using methyl caffeate (MC) to replace CA, and a CAPE yield of 93.21% was achieved via transesterification from MC and PE [ 9 ].…”

Avaliação da composição química e atividade antioxidante da própolis orgânica de Apis mellifera visando à preservação ambiental do ecossistema envolvido

“…A própolis chinesa também é rica em flavonoides e em ácidos fenólicos, sendo que alguns tipos apresentam maior atividade porque possuem em sua composição os ácidos caféico, ferúlico e CAPE (CHEN et al, 2003;AHN et al, 2007;HA, et al, 2012). De acordo com a literatura, a própolis chinesa, argentina e europeia possuem os flavonoides crisina e galangina em grande concentração, os quais são considerados os mais ativos do ponto de vista antioxidante (GARDANA et al, 2007;MOREIRA et al, 2011).…”

Extracción, purificación y transformación enzimática del ácido clorogénico da la pulpa de café

“…Por otro lado, la esterificación de AC y 2-FE catalizada con Novozym® 435 se ha llevado a cabo con altas conversiones y rendimientos (92-100%). Sin embargo, para obtener estos resultados se requiere de una gran cantidad de catalizador (15-17.8 mg de biocatalizador/mg AC) (Widjaja et al, 2008;Chen et al, 2010;Ha et al, 2012). Esto probablemente se debe a la baja afinidad del biocatalizador por el sustrato.…”