title: Optimization of lipase-catalyzed synthesis of acetylated tyrosol by response surface methodology.
abstract: The ability of a noncommercial immobilized lipase from Staphylococcus xylosus (SXLi) to catalyze the transesterification of tyrosol and ethyl acetate was investigated. Response surface methodology was used to evaluate the effects of the temperature (40-60 degrees C), the enzyme amount (50-500 UI), and the ethyl acetate/hexane volume ratio (0.2-1) on the tyrosol acetylation conversion yield. Two independent replicates were carried out under the optimal conditions predicted by the model (reaction temperature 54 degrees C, enzyme amount 500 UI, and volume ratio ethyl acetate/hexane 0.2). The maximum conversion yield reached 95.36 +/- 3.6%, which agreed with the expected value (96.8 +/- 3.7%). The ester obtained was characterized by spectroscopic methods. Chemical acetylation of tyrosol was performed, and the products were separated using HPLC. Among the eluted products from HPLC, mono- and diacetylated derivatives were identified by positive mass spectrometry. Tyrosol and its monoacetylated derivative exert similar antiradicalar activity on 2,2-diphenyl-1-picrylhydrazyle.
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS route de Soukra, 3038 Sfax-Tunisia.
authors.forename: Imen
authors.initials: I
authors.lastname: Aissa
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bouaziz
authors.forename: Hanen
authors.initials: H
authors.lastname: Ghamgui
authors.forename: Amel
authors.initials: A
authors.lastname: Kamoun
authors.forename: Nabil
authors.initials: N
authors.lastname: Miled
authors.forename: Sami
authors.initials: S
authors.lastname: Sayadi
authors.forename: Youssef
authors.initials: Y
authors.lastname: Gargouri
mesh_terms: D000107:Acetylation; D000975:Antioxidants / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000378:metabolism; D004951:Esterification; D016166:Free Radical Scavengers / Q000737:chemistry; D008049:Lipase / Q000378:metabolism*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D013210:Staphylococcus / Q000201:enzymology
chemical_list: D000975:Antioxidants; D004800:Enzymes, Immobilized; D016166:Free Radical Scavengers; C011867:4-hydroxyphenylethanol; D008049:Lipase; D010626:Phenylethyl Alcohol