Highly efficient enzymatic acetylation of flavonoids: Development of solvent-free process and kinetic evaluation

• Published in: Biochemical engineering journal 2017-12, Vol.128 (C), p.106-115
• Main Authors: Milivojević, Ana, Ćorović, Marija, Carević, Milica, Banjanac, Katarina, Vujisić, Ljubodrag, Veličković, Dušan, Bezbradica, Dejan
• Format: Article
• Language: English
• Subjects: BASIC BIOLOGICAL SCIENCES; COPASI; Flavonoid acetylation; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Kinetic parameters; Lipase; Solvent-free
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2017.09.018

[Display omitted] •Lipase-catalyzed, solvent-free acetylation of flavonoid glycosides was conducted.•Triacetin was suitable acyl donor for phloridzin, naringin and esculin as acceptors.•100% conversions were achieved and two produsts – mono- and diester were detected.•Kinetic mechanism based on two reversible Michaelis-Menten reactions was developed.•Kinetic model enabled prediction of system composition within all 72h of reaction. Solubility and stability of flavonoid glycosides, valuable natural constituents of cosmetics and pharmaceuticals, could be improved by lipase-catalyzed acylation. Focus of this study was on development of eco-friendly process for the production of flavonoid acetates. By using phloridzin as model compound and triacetin as acetyl donor and solvent, 100% conversion and high productivity (23.32gl−1day−1) were accomplished. Complete conversions of two other glycosylated flavonoids, naringin and esculin, in solvent-free system were achieved, as well. Comprehensive kinetic mechanism based on two consecutive mono-substrate reactions was established where first one represents formation of flavonoid monoacetate and within second reaction diacetate is being produced from monoacetate. Both steps were regarded as reversible Michaelis-Menten reactions without inhibition. Apparent kinetic parameters for two consecutive reactions (Vm constants for substrates and products and Km constants for forward and reverse reactions) were estimated for three examined acetyl acceptors and excellent fitting of experimental data (R2>0.97) was achieved. Obtained results showed that derived kinetic model could be applicable for solvent-free esterifications of different flavonoid glycosides. It was valid for entire transesterification course (72h of reaction) which, combined with complete conversions and green character of synthesis, represents firm basis for further process development.