title: Highly efficient enzymatic synthesis of an ascorbyl unstaturated fatty acid ester with ecofriendly biomass-derived 2-methyltetrahydrofuran as cosolvent.
abstract: Enzymatic synthesis of ascorbyl undecylenate, an unsaturated fatty acid ester of ascorbic acid, was reported with biomass-derived 2-methyltetrahydrofuran (MeTHF) as the cosolvent. Of the immobilized lipases tested, Candida antarctica lipase B (CAL-B) showed the highest activity for enzymatic synthesis of ascorbyl undecylenate. Effect of reaction media on the enzymatic reaction was studied. The cosolvent mixture, t-butanol-MeTHF (1:4, v/v) proved to be the optimal medium, in which not only ascorbic acid had moderate solubility, but also CAL-B showed a high activity, thus addressing the major problem of the solvent conflict for dissolving substrate and keeping satisfactory enzyme activity. In addition, the enzyme was much more stable in MeTHF and t-butanol-MeTHF (1:4) than in previously widely used organic solvents, t-butanol, 2-methyl-2-butanol, and acetone. The much higher initial reaction rate in this cosolvent mixture may be rationalized by the much lower apparent activation energy of this enzymatic reaction (26.6 vs. 38.1-39.1 kJ/mol) and higher enzyme catalytic efficiency (Vmax /Km , 8.4 vs. 1.3-1.4 h(-1) ). Ascorbyl undecylenate was obtained with the yields of 84-89% and 6-regioselectivity of >99% in t-butanol-MeTHF (1:4) at supersaturated substrate concentrations (60 and 100 mM) after 5-8 h.
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China; College of Biosciences and Bioengineering, South China University of Technology, Guangzhou, 510006, China.
authors.forename: Ying-Dan
authors.initials: YD
authors.lastname: Hu
authors.forename: Ye-Zhi
authors.initials: YZ
authors.lastname: Qin
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Zong
mesh_terms: D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D057005:Bioengineering; D018533:Biomass; D019149:Bioreactors; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism*; D005663:Furans / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D005231:Fatty Acids, Unsaturated; D005663:Furans; D008049:Lipase; C550584:2-methyltetrahydrofuran; D001205:Ascorbic Acid
keywords: ascorbyl fatty acid esters; biomass-derived solvent; kinetics study; lipases; solvent engineering