earticle

영어

Hydroquinone galactoside (HQ-Gal) as a potential skin whitening agent was synthesized by the reaction of lactase (β-galactosidase) from Kluyveromyces lactis, Aspergillus oryzae, Bacillus circulans and Thermus sp. with lactose as a donor and HQ as an acceptor. Among these lactases, the acceptor reaction involving HQ and lactose with K.lactis lactase showed higher conversion ratio to HQ-Gal(60.27%). HQ-Gal was purified using butanol partitioning and silica-gel column chromatography. The structure of the purified HQ-Gal was determined by nuclear magnetic resonance and the ionic product was observed at m/z 295(C12H16O7Na)+ using matrix assisted laser desorption ionization time-of-flight mass spectrometry. HQ-Gal was identified as 4-hydroxyphenyl-β-D-galactopyranoside. The optimum conditions for HQ-Gal synthesis by K.lactis determined using response surface methodology were 50 mM HQ, 60 mM lactose, and 20 U mL-1 lactase. These conditions produced a yield of 2.01 g L-1 HQ-Gal. The half maximal inhibitory concentration (IC50) of diphenylpicryl-hydrazyl radical scavenging activity was 3.31 mM indicating a similar anti-oxidant activity compared to β-arbutin(IC50=3.95 mM). The Ki value of HQ-Gal(0.75 mM) against tyrosinase was smaller than that of β-arbutin (Ki=1.97 mM),indicating superiority as an inhibitor.