Enzymatic synthesis and characterization of hydroquinone galactoside using Kluyveromyces lactis lactase.

Abstract

Hydroquinone galactoside (HQ-Gal) as a potential skin whitening agent was synthesized by the reaction of lactase (beta-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 a 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-beta-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 diphenylpicrylhydrazyl scavenging activity was 3.31 mM, indicating a similar antioxidant activity compared to beta-arbutin (IC50=3.95 mM). The Ki value of HQ-Gal (0.75 mM) against tyrosinase was smaller than that of beta-arbutin (Ki=1.97 mM), indicating its superiority as an inhibitor. HQ-Gal inhibited (23%) melanin synthesis without being significantly toxic to the cells, while beta-arbutin exhibited only 8% reduction of melanin synthesis in B16 melanoma cells compared with the control. These results indicate that HQ-Gal may be a suitable functional component in the cosmetics industry.

• Authors: Go-Eun Kim, Jin-Ha Lee, Sun-Hwa Jung, Eun-Seong Seo, Sheng-De Jin, Ghahyun J Kim, Jaeho Cha, Eui-Joong Kim, Ki-Deok Park, Doman Kim
• Journal: Journal of agricultural and food chemistry (J Agric Food Chem) Vol. 58 Issue 17 Pg. 9492-7 (Sep 08 2010) ISSN: 1520-5118 [Electronic] United States
• PMID: 20687552 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Galactosides
• Hydroquinones
• Lactase

Topics

• Animals
• Cell Line, Tumor
• Galactosides (chemical synthesis)
• Hydroquinones (chemical synthesis, chemistry)
• Kluyveromyces (enzymology)
• Lactase (metabolism)
• Mice
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization