title: Hydroxytyrosol acyl esters: biosynthesis and activities.
abstract: We previously reported the production of high yields of hydroxytyrosol through the bioconversion of tyrosol. In the present work, hydroxytyrosol was subjected to the lipase catalyzed acylation aiming for the recovery of more lipophilic esters that might be easily incorporated in cosmetic and food preparations. Hydroxytyrosyl acetate and hydroxytyrosyl oleate were produced with respective molar esterification yields of 98% and 78%. DPPH free radical quenching potency demonstrated that the acylation of hydroxytyrosol did not alter its antioxidant activity. The acylated esters were shown to be more effective than the natural antioxidant: caffeic acid and two synthetic ones as BHA and BHT. Antiproliferative activity on human cervical cells (HeLa) resulted in IC(50) values of 0.46, 0.42 and 0.33 mM for hydroxytyrosol and its acetyl and oleyl esters, respectively. Additionally, when used at a non-cytotoxic concentration (100 μM), these compounds showed significant effectiveness in preventing iron-induced oxidative stress, resulting in a reduction of 30%, 36% and 38% in thiobarbituric acid-reactive substance production, respectively.
authors.affiliation: Environnemental Bioprocesses Laboratory, Sfax Biotechnology Centre, P.O. Box 1177, 3038, Sfax, Tunisia.
authors.forename: Zouhaier
authors.initials: Z
authors.lastname: Bouallagui
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bouaziz
authors.forename: Salwa
authors.initials: S
authors.lastname: Lassoued
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Engasser
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ghoul
authors.forename: Sami
authors.initials: S
authors.lastname: Sayadi
mesh_terms: D000085:Acetates / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D002396:Catechols / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D004800:Enzymes, Immobilized; D004951:Esterification; D005656:Fungal Proteins; D006367:HeLa Cells; D006801:Humans; D008049:Lipase / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000085:Acetates; D002396:Catechols; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; C524604:hydroxytyrosyl acetate; C005975:3,4-dihydroxyphenylethanol; C093667:Novozyme 435; D008049:Lipase; D010626:Phenylethyl Alcohol