Enzymatic Synthesis of 1, 2-Hexanediol Galactoside by Whole Cells of β-Galactosidase-containing Recombinant Escherichia coli

Abstract

Recently, it has been reported that some preservatives used in cosmetics lead to skin problems. Among the many cosmetic ingredients, 1, 2-hexanediol (HD) is used as both a preservative and humectant. In order to develop safer ingredients, we studied the synthesis of 1, 2-hexanediol galactoside (HD-G) by a transgalactosylation reaction using β-galactosidase (β-gal)-containing recombinant Escherichia coli cells. The transgalactosylation reaction was carried out under high-lactose conditions for 24 hr. After 12 hr had elapsed, a new spot was identified by thin-layer chromatography (TLC) analysis, and we presumptively designated this new spot as HD-G. Then, we carried out the purification of the presumptive HD-G spot from the reaction mixture by using silica gel chromatography, and its mass was measured by electrospray ionization-mass spectrometry. The purified new spot on the chromatograph was identified a sodium adduct ion ([M+Na] + , m/z = 303.1423) of HD-G. In addition, when purified HD-G was hydrolyzed using commercially available E. coli β-gal, it was observed that a galactose molecule was released from HD-G. That is, it was demonstrated that HD-G is a galactoside derivative of HD. Finally, we confirmed that HD-G was enzymatically synthesized by E. coli β -gal as a new molecular entity. In the future, we plan to determine the minimum inhibitory concentrations of HD-G against different bacterial species. The cytotoxicity of HD-G against human skin cells will also be examined. It is expected hopefully that the galactosylation of HD would improve the functionality of HD-G.Key words : 1, 2-Hexanediol, β-Galactosidase, cosmetic preservative, Escherichia coli, transgalactosylation *Corresponding author *Tel : +82-43-820-5246, Fax : +82-43-820-5272 *E-mail : khjung@cjnu.ac.kr This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 본 연구에서