title: Enzymatic synthesis of a novel glycolipid biosurfactant, mannosylerythritol lipid-D and its aqueous phase behavior.
abstract: Mannosylerythritol lipids (MELs) produced by yeasts are one of the most promising glycolipid biosurfactants. In this study, we succeeded in the preparation of a novel MEL homolog having no acetyl groups, namely MEL-D. MEL-D was synthesized by lipase-catalyzed hydrolysis of acetyl groups from a known MEL, and identified as 4-O-[2',3'-di-O-alka(e)noyl-β-d-mannopyranosyl]-(2R,3S)-erythritol. The obtained MEL-D showed a higher critical aggregation concentration (CAC=1.2 × 10(-5)M) and hydrophilicity compared to known MELs, retaining an excellent surface tension lowering activity (the surface tension at the CAC was 24.5mN/m). In addition, we estimated the binary phase diagram of the MEL-D-water system based on a combination of visual inspection, polarized optical microscopy, and SAXS measurement. From these results, MEL-D was found to self-assemble into a lamellar (L(α)) structure over all ranges of concentration. Meanwhile, the one-phase L(α) region of MEL-D was extended wider than those of known MELs. MEL-D might keep more water between the polar layers in accordance with the extension of the interlayer spacing (d). These results suggest that the newly obtained MEL-D would facilitate the application of MELs in various fields as a lamellar-forming glycolipid with higher hydrate ability.
authors.affiliation: Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5-2, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Tokuma
authors.initials: T
authors.lastname: Fukuoka
authors.forename: Takashi
authors.initials: T
authors.lastname: Yanagihara
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Imura
authors.forename: Tomotake
authors.initials: T
authors.lastname: Morita
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe
authors.forename: Dai
authors.initials: D
authors.lastname: Kitamoto
mesh_terms: D006017:Glycolipids / Q000138:chemical synthesis / Q000737:chemistry*; D006868:Hydrolysis; D008049:Lipase / Q000737:chemistry*; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D006017:Glycolipids; D013501:Surface-Active Agents; C439671:mannosylerythritol lipid; D014867:Water; D008049:Lipase