title: Feruloyl esterase-catalysed synthesis of glycerol sinapate using ionic liquids mixtures.
abstract: The ability of a feruloyl esterase (AnFaeA), either in free or immobilised (cross-linked enzyme aggregates) form, to catalyse the esterification of glycerol, a major by-product of the biodiesel industry, with sinapic acid was studied in four hexafluorophosphate anion-containing ionic liquids: ([Bmim][PF(6)], [Omim][PF(6)], [C(2)OHmim][PF(6)] and [C(5)O(2)mim][PF(6)]). Such ionic liquids are considered 'green' reaction systems. The synthetic reaction was optimised in [C(2)OHmim][PF(6)] and the highest conversion yield was 72.5+/-2.1%, while, at the same reaction conditions in [C(5)O(2)mim] [PF(6)], a similar conversion yield was obtained (76.7+/-1.5%). AnFaeA was active in its free and immobilised form, with the latter retaining a part of its synthetic activity after 5 consecutive 24h-period reaction cycles. Sinapic acid was esterified to one of the primary hydroxyl groups of glycerol and retained, after esterification, 63.1+/-0.3% and 89.5+/-1.1% of its antioxidant activity against low-density lipoprotein oxidation, when added at concentrations of 10 and 60muM, respectively, in the assay mixture.
authors.affiliation: BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Street, Zografou Campus, 15700 Athens, Greece.
authors.forename: Christina
authors.initials: C
authors.lastname: Vafiadi
authors.forename: Evangelos
authors.initials: E
authors.lastname: Topakas
authors.forename: Victoria R
authors.initials: VR
authors.lastname: Nahmias
authors.forename: Craig B
authors.initials: CB
authors.lastname: Faulds
authors.forename: Paul
authors.initials: P
authors.lastname: Christakopoulos
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000378:metabolism; D004951:Esterification; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism*; D055772:Green Chemistry Technology; D052578:Ionic Liquids / Q000737:chemistry*; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000378:metabolism; D010084:Oxidation-Reduction; D013696:Temperature; D014867:Water
chemical_list: D000975:Antioxidants; D002412:Cations; D003373:Coumaric Acids; D004800:Enzymes, Immobilized; D052578:Ionic Liquids; D008077:Lipoproteins, LDL; D014867:Water; C073734:sinapinic acid; D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase; D005990:Glycerol