title: Regioselective synthesis of kojic acid esters by Bacillus subtilis protease.
abstract: The lipophilicity of kojic acid [5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one] was improved by esterifying kojic acid with either divinyl adipate, vinyl hexanoate, vinyl octanoate or vinyl decanoate using protease from Bacillus subtilis for 7 d. 1H-NMR and 13C-NMR showed that the primary hydroxyl group at the C-7 position of kojic acid was regioselectively esterified to afford 7-O-vinyl adipoyl kojic acid, 7-O-hexanoyl kojic acid, 7-O-octanoyl kojic acid and 7-O-decanoyl kojic acid (13-27% yield). The kojic acid esters had radical scavenging activities, inhibited tyrosinase activity and was biodegradable.
authors.affiliation: New Energy and Industrial Technology Development Organization, Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Raku
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tokiwa
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry* / Q000201:enzymology; D001673:Biodegradation, Environmental; D002396:Catechols / Q000737:chemistry*; D010450:Endopeptidases / Q000737:chemistry*; D004789:Enzyme Activation; D004951:Esterification; D004952:Esters; D016166:Free Radical Scavengers / Q000737:chemistry; D014442:Monophenol Monooxygenase / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D011753:Pyrones / Q000032:analysis / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D014867:Water / Q000737:chemistry
chemical_list: D002396:Catechols; D004952:Esters; D016166:Free Radical Scavengers; D011753:Pyrones; D014867:Water; C011890:kojic acid; D014442:Monophenol Monooxygenase; D010450:Endopeptidases; C034221:catechol; D010100:Oxygen