Jae-Hoon Shim

Hallym University, Sŏul, Seoul, South Korea

Are you Jae-Hoon Shim?

Claim your profile

Publications (35)76.34 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The efficacy of Ligularia fischeri (LF) for managing diabetic complications was evaluated by assessing inhibitory effects against advanced glycation end product (AGE) formation, rat lens aldose reductase (RLAR), and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging. The ethyl acetate fraction from 70% ethanol extracts of LF showed the highest DPPH radical scavenging activity of 53.90% at a concentration of 3.3 μg/mL. The ethyl acetate fraction exhibited the most potent AGE formation inhibition of 73.57% at a concentration of 55 μg/mL and showed the most potent RLAR inhibition of 88.97% at a concentration of 11.11 μg/mL. The ethyl acetate fraction exhibited the most potent antioxidant and anti-diabetic effects. Nuclear magnetic resonance via bioactivity-guided fractionation of the LF ethyl acetate fraction revealed that 3,4-dicaffeoylquinic acid was the bioactive compound. This compound from LF can be effective for prevention or treatment of diabetic complications.
    Food science and biotechnology 12/2014; 23(6). · 0.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We studied the activity of a debranching enzyme (TreX) from Sulfolobus solfataricus on glycogen-mimic substrates, branched maltotetraosyl-β-cyclodextrin (Glc4-β-CD), and natural glycogen to better understand substrate transglycosylation and the effect thereof on glycogen debranching in microorganisms. The validation test of Glc4-β-CD as a glycogen-mimic substrate showed that it followed the breakdown process of the well-known yeast and rat liver extract. TreX catalyzed both hydrolysis of α-1,6-glycosidic linkages and transglycosylation at relatively high (>0.5 mM) substrate concentrations. TreX transferred maltotetraosyl moieties from the donor substrate to acceptor molecules, resulting in the formation of two positional isomers of dimaltotetraosyl-α-1,6-β-cyclodextrin [(Glc4)2-β-CD]; these were 6(1),6(3)- and 6(1),6(4)-dimaltotetraosyl-α-1,6-β-CD. Use of a modified Michaelis-Menten equation to study substrate transglycosylation revealed that the kcat and Km values for transglycosylation were 1.78 × 10(3) s(-1) and 3.30 mM, respectively, whereas the values for hydrolysis were 2.57 × 10(3) s(-1) and 0.206 mM, respectively. Also, enzyme catalytic efficiency (the kcat/Km ratio) increased as the degree of polymerization of branch chains rose. In the model reaction system of Escherichia coli, glucose-1-phosphate production from glycogen by the glycogen phosphorylase was elevated ∼1.45-fold in the presence of TreX compared to that produced in the absence of TreX. The results suggest that outward shifting of glycogen branch chains via transglycosylation increases the number of exposed chains susceptible to phosphorylase action. We developed a model of the glycogen breakdown process featuring both hydrolysis and transglycosylation catalyzed by the debranching enzyme.
    Journal of bacteriology 03/2014; · 3.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Structural modification of rice and barley starches with Neisseria polysaccharea amylosucrase (NpAS) was conducted, and relationship between structural characteristics and resistant starch (RS) contents of NpAS-treated starches was investigated. Pre-gelatinised rice and barley starches were treated with NpAS. NpAS-treated starches were characterised with respect to morphology, X-ray diffraction pattern, amylopectin branch-chain distribution, and RS content, and their structural characteristics were correlated to RS contents. Regardless of amylose contents of native starches, NpAS-treated (relative to native) starches possessed lower and higher proportions of shorter (DP 6-12) and intermediate (DP 13-36) amylopectin (AP) branch-chains, respectively. RS contents were higher for NpAS-treated starches relative to native starches, and maximum RS contents were obtained for NpAS-treated starches of waxy rice and barley genotypes. Amylose contents were not associated with RS contents of NpAS-treated starches. However, shorter and intermediate AP branch-chain portions were negatively and positively correlated to RS contents of NpAS-treated starches, respectively.
    Food Chemistry 06/2013; 138(2-3):966-75. · 3.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The rheological and cooking properties of gluten-free noodles prepared with dry- and wet-milled rice flours were characterized. Dry-milled rice flour with a higher degree of starch damage exhibited greater water hydration properties than wet-milled rice flour at room temperature. However, the pasting results of rice flour suspensions demonstrated that wet-milled rice flour showed a higher value of peak viscosity due to its great swelling power upon starch gelatinization. The similar thermo-mechanical tendency was observed in a rice dough system by Mixolab. In the planar extensional test, the noodle dough sample prepared with dry-milled rice flour exhibited higher elongational viscosity which could be favorably correlated to more resistance of dry-milled rice noodle strands to extension. When rice noodles were cooked, increased cooking loss was observed in dry-milled rice noodles which was attributed to great water solubility derived from a higher degree of starch damage.
    Journal of Food Engineering. 05/2013; 116(1):213–217.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lipid-laden peripheral tissue cells release cholesterol to an extracellular acceptor such as high-density lipoprotein (HDL). Foam cells are formed at the first stage of atherosclerosis development. This study investigated whether sage weed (Salvia plebeia) extract (SWE) influences cholesterol handling of J774A1 murine macrophages. A murine macrophage cell line, J774A1, was used in this study. Oxidized low-density lipoproteins (LDL) treatment was used for foam cell formation, which was confirmed using Oil red O staining. The oxidized LDL uptake and cholesterol efflux from lipid-laden foam cell-associated proteins were detected by western blot analysis. Also, transcriptional levels of these associated genes were examined using reverse transcription-PCR. Also, cholesterol efflux was measured using NBD-cholesterol efflux assay. Non-toxic SWE at ≥10 µg/ml attenuated scavenger receptor (SR)-B1 expression of macrophages induced by oxidized LDL for 6 h, which was achieved at its transcriptional levels. Consistently, SWE suppressed oxidized LDL-stimulated cellular lipid accumulation and foam cell formation due to downregulated SR-B1. SWE upregulated the protein expression and mRNA levels of ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) in lipid-laden foam cells, both responsible for cholesterol efflux. In addition, SWE promoted apolipoprotein E (apoE) secretion from oxidized LDL-induced foam cells. Cholesterol efflux was enhanced by ≥10 µg/ml SWE most likely through the induction of ABCA1 and ABCG1 and the secretion of apoE. Although 10 µM homoplantaginin, a compound mainly present in sage weeds, did not influence cellular expression of ABCA1 and ABCG1, it suppressed oxidized LDL-enhanced SR-B1 induction and foam cell formation. These results demonstrate that SWE antagonized oxidized LDL uptake and promoted cholesterol efflux in lipid-laden macrophages. Therefore, SWE may serve as a protective therapeutic agent against the development of atherosclerosis.
    International Journal of Molecular Medicine 08/2012; 30(5):1105-12. · 1.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Glycans bearing modified hydroxyl groups are common in biology but because these modifications are added after assembly, enzymes are not available for the transfer and coupling of hydroxyl-modified monosaccharide units. Access to such enzymes could be valuable, particularly if they can also introduce 'bio-orthogonal tags'. Glycosynthases, mutant glycosidases that synthesize glycosides using glycosyl fluoride donors, are a promising starting point for creation of such enzymes through directed evolution. Inspection of the active site of a homology model of the GH1 Agrobacterium sp. β-glycosidase, which has both glucosidase and galactosidase activity, identified Q24, H125, W126, W404, E411 and W412 as amino acids that constrain binding around the 3-OH group, suggesting these residues as targets for mutation to generate an enzyme capable of handling 3-O-methylated sugars. Site-directed saturation mutagenesis at these positions within the wild-type β-glycosidase gene and screening via an on-plate assay yielded two mutants (Q24S/W404L and Q24N/W404N) with an improved ability to hydrolyze 4-nitrophenyl 3-O-methyl-β-D-galactopyranoside (3-MeOGal-pNP). Translation of these mutations into the evolved glycosynthase derived from the same glucosidase (2F6) yielded glycosynthases (AbgSL-T and AbgNN-T, where T denotes transferase) capable of forming 3-O-methylated glucosides on multi-milligram scales at rates approximately 5 and 40 times greater, respectively, than the parent glycosynthase.
    Protein Engineering Design and Selection 08/2012; 25(9):465-72. · 2.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to understand the relationship between chemical structure and physical properties of cereal β-glucans, the β-glucans with identical Mw (98.4–99.2 kDa) and Rg (21.1–22.0 nm) were isolated from chal and gwangan barley, and ohl oat, and their linkage structure, flow behavior, and thermal properties were investigated. Previously, we established a purification method of 3-O-cellobiosyl-glucose (DP3) and 3-O-cellotriosyl-glucose (DP4) (Yoo, Lee, Chang, Lee, & Yoo, 2007) and applied these authentic standards to quantify the ratio of β-(1,4)/(1,3) linkages in cereal β-glucans. β-Glucans isolated from two barley cultivars had greater proportion of DP3 than did the oat, and within barley cultivars chal barley β-glucan had significantly larger amount of DP3 over gwangan cultivar. Thus, chal barley β-glucan had the greatest molar ratio (2.53) of DP3 to DP4, and ohl oat had the lowest (1.51). While all the β-glucan solutions showed strong shear thinning behavior, ohl oat β-glucan with higher proportion of DP4 exhibited the highest viscosity among the β-glucan samples. After 3 freeze-thaw cycles of 3% (w/v) β-glucan samples, chal barley β-glucan had lower onset (To) and peak (Tp) temperatures (28.3 and 36.7 °C, respectively) than those of gwangan barley (33.6 and 39.9 °C) and ohl oat (37.9 and 46.9 °C) did, and the heat scan profiles were thermoreversible. The To and Tp of inter-chain associations decreased as the DP3:DP4 ratio of the β-glucan increased. From this study, it was suggested that cellotetraosyl units and longer β-(1,4)-linked segments would be a major contributor for improving solution viscosity and gel formation of cereal β-glucans.
    Carbohydrate Polymers 08/2012; 89(4):1238–1243. · 3.48 Impact Factor
  • Source
    Jae-Hoon Shim, Byung-Chul Oh
    [Show abstract] [Hide abstract]
    ABSTRACT: The enzyme phytase has broad biotechnological applications, especially in the reduction of phytate, antinutritional factors that chelate essential minerals, in human and animal food. We investigated the enzymatic properties of β-propeller phytase (BPP) from Bacillus amyloliquefaciens DS11. Thermal refolding analysis demonstrated that BPP can remarkably restore its enzymatic activity in the presence of 5 mM Ca(2+) to 87% of its original activity after heating to 100 °C and subsequent cooling, indicating that the enzyme requires Ca(2+) for appropriate refolding. Furthermore, pH-dependent kinetic studies showed that BPP required excess Ca(2+) for its enzymatic activity as the pH decreased, suggesting that the optimal Ca(2+)-phytate ratio for enzymatic catalysis depends on the pH value of the environment. Finally, we verified the practical application of BPP at two different pH's using soybean meal as a natural source of phytate. As compared to a commercial phytase, BPP efficiently hydrolyzed food phytate over neutral pH ranges.
    Journal of Agricultural and Food Chemistry 07/2012; · 3.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the acute metabolic effects of isoflavones from Pueraria lobata (Willd.) Ohwi (IPL) in ovariectomized (OVX) mice. After 4 weeks of IPL feeding at 500 mg/day/kg body weight (OVX500), plasma 17β-estradiol concentrations were significantly higher (+25%, p < 0.05), whereas plasma triglyceride levels were significantly lower in OVX mice (-15%, p < 0.05) compared with controls. Abdominal adipose tissue weight was marginally reduced in IPL-fed groups compared with OVX controls and the plasma levels of liver enzymes were unchanged. In addition, IPL significantly inhibited the reduction of bone mineral density in the femurs of OVX mice (OVX200, +22%; OVX500, +26%; p < 0.05) compared with controls after 4 weeks of IPL feeding. In quantitative polymerase chain reaction analysis the expression of aromatase was significantly suppressed and SULT1E1 was increased by IPL feeding, showing that IPL feeding may not alter the risk for breast cancer in mice. Our results suggest that IPL could ameliorate menopausal symptoms in mice. Further studies will confirm the effects of IPL in humans. Copyright © 2012 John Wiley & Sons, Ltd.
    Phytotherapy Research 03/2012; · 2.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study was conducted to evaluate the possible subacute toxicity of gamma-irradiated Tarakjuk. Tarakjuk was irradiated at a dose of 30 kGy at room temperature. For the animal study, AIN-93G as a control diet and 30 kGy irradiated and non-irradiated Tarakjuk diets were administered to male and female ICR mice (10 mice per group) for 3 months. During the experimental period, the group fed 30 kGy irradiated Tarakjuk did not show any changes in appearance, behavior, mortality, body weight, organ weight, or food consumption compared to control. Further, all biochemical parameters were in normal ranges. In the histopathological examination of liver and kidney tissues of ICR mice, there were no significant differences between the control and 30 kGy irradiated Tarakjuk groups. These results indicate that Tarakjuk irradiated at 30 kGy did not cause any toxic effects under these experimental conditions.
    Journal of the Korean Society of Food Science and Nutrition 01/2012; 41(11).
  • Source
    Hwan-Ung Yong, Seonmi Kim, Jae-Hoon Shim
    [Show abstract] [Hide abstract]
    ABSTRACT: Alkyl glucosides were synthesized using the transglycosylation reaction of Celluclast, the cellulase from Trichoderma reesei, with cellobiose and various alcohols. Glucose as a by-product of the reaction was removed using the immobilized yeast system. Among the alkyl glucoside products, the acceptor products of methanol and ethanol were confirmed as methyl -D-glucopyranoside and ethyl -D-glucopyranoside via MALDI-TOF MS and enzymatic analysis. Optimal yields of methyl -glucoside and ethyl -glucoside were 65.3% (mol/mol) and 59.0% (mol/mol), respectively, based on cellobiose consumed.
    Journal of the Korean Society of Food Science and Nutrition 01/2012; 41(10).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Wild yeasts on the surface of various fruits including grapes were surveyed to obtain yeast strains suitable for fermenting a novel wine with higher alcohol content and supplemented with rice starch. We considered selected characteristics, such as tolerance to alcohol and osmotic pressure, capability of utilizing maltose, and starch hydrolysis. Among 637 putative yeast isolates, 115 strains exhibiting better growth in yeast-peptone-dextrose broth containing 30% dextrose, 7% alcohol, or 2% maltose were selected, as well as five α-amylase producers. Nucleotide sequence analysis of the 26S rDNA gene classified the strains into 13 species belonging to five genera; Pichia anomala was the most prevalent (41.7%), followed by Wickerhamomyces anomalus (19.2%), P. guilliermondii (15%), Candida spp. (5.8%), Kodamaea ohmeri (2.5%), and Metschnikowia spp. (2.5%). All of the α-amylase producers were Aureobasidium pullulans. Only one isolate (NK28) was identified as Saccharomyces cerevisiae. NK28 had all of the desired properties for the purpose of this study, except α-amylase production, and fermented alcohol better than commercial wine yeasts.
    Mycobiology 03/2011; 39(1):33-9. · 0.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mutants with deletion mutations in the glg and mal gene clusters of Escherichia coli MC4100 were used to gain insight into glycogen and maltodextrin metabolism. Glycogen content, molecular mass, and branch chain distribution were analyzed in the wild type and in ΔmalP (encoding maltodextrin phosphorylase), ΔmalQ (encoding amylomaltase), ΔglgA (encoding glycogen synthase), and ΔglgA ΔmalP derivatives. The wild type showed increasing amounts of glycogen when grown on glucose, maltose, or maltodextrin. When strains were grown on maltose, the glycogen content was 20 times higher in the ΔmalP strain (0.97 mg/mg protein) than in the wild type (0.05 mg/mg protein). When strains were grown on glucose, the ΔmalP strain and the wild type had similar glycogen contents (0.04 mg/mg and 0.03 mg/mg protein, respectively). The ΔmalQ mutant did not grow on maltose but showed wild-type amounts of glycogen when grown on glucose, demonstrating the exclusive function of GlgA for glycogen synthesis in the absence of maltose metabolism. No glycogen was found in the ΔglgA and ΔglgA ΔmalP strains grown on glucose, but substantial amounts (0.18 and 1.0 mg/mg protein, respectively) were found when they were grown on maltodextrin. This demonstrates that the action of MalQ on maltose or maltodextrin can lead to the formation of glycogen and that MalP controls (inhibits) this pathway. In vitro, MalQ in the presence of GlgB (a branching enzyme) was able to form glycogen from maltose or linear maltodextrins. We propose a model of maltodextrin utilization for the formation of glycogen in the absence of glycogen synthase.
    Journal of bacteriology 03/2011; 193(10):2517-26. · 3.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sucrose isomerase (SIase) has been used to produce palatinose, a structural isomer of sucrose, which has many beneficial health properties, such as low-glycemic and low-insulinemic indices. A gene corresponding to SIase from Enterobacter sp. FMB-1 was expressed in Lactococcus lactis MG1363 using the P170 expression system. The autoinducible promoter (P170) and an optimized signal peptide (SP310mut2) were used to induce and secrete SIase in L. lactis. One-step Ni-NTA affinity chromatography and Western blot analysis demonstrated that SIase was successfully secreted to the culture supernatant, although 60% of the recombinant enzymes were retained inside the cells. The production of the recombinant SIase was highly correlated with pH (pH 6) and glucose concentration (30g/L) of the medium. The extracellularly produced recombinant SIase was functionally active, effectively transforming 50g/L sucrose to 36g/L palatinose, with a conversion rate of 72% in the culture supernatant.
    Bioresource Technology 11/2010; 101(22):8828-33. · 5.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Phytate is an antinutritional factor that influences the bioavailability of essential minerals by forming complexes with them and converting them into insoluble salts. To further our understanding of the chemistry of phytate's binding interactions with biologically important metal cations, we determined the stoichiometry, affinity, and thermodynamics of these interactions by isothermal titration calorimetry. The results suggest that phytate has multiple Ca(2+)-binding sites and forms insoluble tricalcium- or tetracalcium-phytate salts over a wide pH range (pH 3.0-9.0). We overexpressed the β-propeller phytase from Hahella chejuensis (HcBPP) that hydrolyzes insoluble Ca(2+)-phytate salts. Structure-based sequence alignments indicated that the active site of HcBPP may contain multiple calcium-binding sites that provide a favorable electrostatic environment for the binding of Ca(2+)-phytate salts. Biochemical and kinetic studies further confirmed that HcBPP preferentially recognizes its substrate and selectively hydrolyzes insoluble Ca(2+)-phytate salts at three phosphate group sites, yielding the final product, myo-inositol 2,4,6-trisphosphate. More importantly, ITC analysis of this final product with several cations revealed that HcBPP efficiently eliminates the ability of phytate to chelate several divalent cations strongly and thereby provides free minerals and phosphate ions as nutrients for the growth of bacteria. Collectively, our results provide significant new insights into the potential application of HcBPP in enhancing the bioavailability and absorption of divalent cations.
    Biochemistry 10/2010; 49(47):10216-27. · 3.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract To increase the water solubility of puerarin, an isoflavonoid derived from Radix puerariae, a puerarin inclusion complex with cycloamylose was enzymatically synthesized by combining maltogenic amylase reactions from Bacillus stearothermophilus (BSMA) and 4-α-glucanotransferase from Thermus scotoductus (TSαGT). The puerarin transfer products, including maltosyl-α-(1→6)-puerarin as a major product generated by BSMA, were reacted with TSαGT in the presence of amylose. The molecular weights and chemical structures of the reaction products were determined using TLC, HPLC and MALDI-TOF/MS. An analysis of the reaction products revealed that the maltosyl-α-(1→6)-puerarin–cycloamylose complex was formed by an elongation reaction and cyclization of TSαGT. The results indicate that TSαGT does not have substrate affinity towards puerarin or glucosyl α-(1→6)-puerarin; however, it did have an affinity towards maltosyl-α-(1→6)-puerarin in which the first glucose of the maltosyl residue is linked through an O-glucosidic bond.
    06/2010; 28(3):209-214.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The transglycosylation reaction of maltodextrin glucosidase (MalZ) cloned and purified from Escherichia coli K12 was characterized and applied to the synthesis of branched oligosaccharides. Purified MalZ preferentially catalyzed the hydrolysis of maltodextrin, gamma-cyclodextrin (CD), and cycloamylose (CA). In addition, when the enzyme was incubated with 5% maltotriose (G3), a series of transfer products were produced. The resulting major transfer products, annotated as T1, T2, and T3, were purified and their structures were determined by TLC, MALDI-TOF/MS, (13)C NMR, and enzymatic analysis. T1 was identified as a novel compound, maltosyl alpha-1,3-maltose, whereas T2 and T3 were determined to be isopanose and maltosyl-alpha-1,6-maltose, respectively. These results indicated that MalZ transferred sugar moiety mainly to C-3 or C-6-OH of glucose of the acceptor molecule. To obtain highly concentrated transfer products, the enzyme was reacted with 10% liquefied cornstarch, and then glucose and maltose were removed by immobilized yeast. The T1 content of the resulting reaction mixture reached 9.0%. The mixture of T1 containing a nigerose moiety can have an immunopotentiating effect on the human body and may be a potential functional sugar stuff.
    Biochemical and Biophysical Research Communications 06/2010; 397(1):87-92. · 2.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The maltogenic amylase from Bacillus stearothermophilus (BSMA) is a valuable biocatalyst that has been used to transglycosylate natural glycosides to improve solubility. To ensure safety, BSMA was produced in Bacillus subtilis, using new shuttle vector-based expression vectors. The transglycosylation of puerarin was also conducted with crude BSMA and analyzed. Two expression systems, each containing one of the promoters from the genes encoding Bacillus licheniformis maltogenic amylase (BLMA) and an alpha-amylase from B. subtilis NA64 (amyR2), were constructed. The amyR2 promoter system was chosen as the best system; it yielded 107 mg of pure BSMA from a 2 L culture. In the transglycosylation reactions of puerarin using crude BSMA, relative amounts for maltosyl-alpha-(1 --> 6)-puerarin, glucosyl-alpha-(1 --> 6)-puerarin, glucosyl-alpha-(1 --> 3)-puerarin, and puerarin were determined as 26:18:7:49. A two-step purification process, including gel permeation chromatography, yielded 1.7 g of the transfer products from 3 g of puerarin. The crude BSMA produced from a host generally recognized as safe (B. subtilis) can be used to transglycosylate various functional compounds. The expression system developed in this study will be helpful for the production of other food-grade enzymes by B. subtilis.
    Journal of the Science of Food and Agriculture 05/2010; 90(7):1179-84. · 1.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A gene encoding a hyperthermostable maltogenic amylase of Staphylothermus marinus (SMMA) was cloned and overexpressed in Escherichia coli. SMMA consisted of 696 amino acids with a predicted molecular mass of 82.5 kDa. The enzyme was active in acidic conditions (pH 3.5-5.0), with an optimal pH of 5.0, and was extremely thermostable, with a temperature optimum of 100 degrees C and a melting temperature of 109 degrees C, both of which extremely favored the starch conversion process. SMMA hydrolyzed linear malto-oligosaccharides, starch, cyclodextrins, and cycloamylose, primarily to maltose and glucose, and showed highest activity toward acarbose and pullulan, hydrolyzed to acarviosine-glucose and panose, respectively. Investigation of the cleavage mode using (14)C-maltoheptaose revealed that SMMA preferentially hydrolyzed the first and second glycosidic bonds from the reducing end. To our knowledge, this enzyme is the most thermostable maltogenic amylase yet reported, and might be of potential value in the food and starch industries.
    New Biotechnology 04/2010; 27(4):300-7. · 1.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the effects of puerarin (8-C-glucosyl-7,4′-dihydroxy isoflavone), an isoflavone found in Kudzu roots (Pueraria lobata), and its glycosides (enzymatically synthesised, water-soluble derivatives of puerarin) on melanogenesis in vitro. Puerarin and its glycosides reduced mushroom tyrosinase activity by 88 and 67% at 4.8mM, respectively, in a concentration-dependent manner. The puerarin glycosides were less effective than puerarin at the same concentration but showed a comparable inhibitory effect at a concentration at which puerarin is insoluble in water. In cultured B16 melanocytes, the melanin content was reduced significantly; moreover, tyrosinase activity was inhibited significantly by both puerarin and its glycosides when added at a concentration of 480μM. DNA microarray and RT-PCR analyses showed significant downregulation of the expression of microphthalmia-associated transcription factor (MITF) and its target genes. The protein expression of MITF and tyrosinase was also downregulated significantly by 40 and 50%, respectively. Our findings suggest that puerarin and its glycosides cause hypopigmentation via dual mechanisms: by inhibiting tyrosinase activity directly and by altering the expression of melanogenesis-related genes, such as MITF and tyrosinase. Therefore, puerarin and its glycosides may have potential for the development of functional cosmetics causing hypopigmentation. KeywordsPuerarin-Melanogenesis-Hypopigmentation-Tyrosinase-Melanin-B16 murine melanocytes-Microarray analysis
    European Food Research and Technology 01/2010; 231(1):75-83. · 1.39 Impact Factor

Publication Stats

164 Citations
76.34 Total Impact Points

Institutions

  • 2010–2014
    • Hallym University
      • Department of Food Science and Nutrition
      Sŏul, Seoul, South Korea
    • University of Incheon
      Sŏul, Seoul, South Korea
  • 2012
    • University of British Columbia - Vancouver
      • Department of Chemistry
      Vancouver, British Columbia, Canada
  • 2002–2011
    • Seoul National University
      • • Department of Agricultural Biotechnology
      • • Department of Food and Animal Biotechnology
      Sŏul, Seoul, South Korea
  • 2007
    • McGill University
      • Department of Food Science and Agricultural Chemistry
      Montréal, Quebec, Canada