• Mycobiology
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• v.45 no.3
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• pp.199-203
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• 2017

This study was done to produce ${\gamma}$-aminobutyric acid (GABA) from wild yeast as well as investigate its anti-hyperglycemic effects. Among ten GABA-producing yeast strains, Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1 produced high GABA concentration of $134.4{\mu}g/mL$ and $179.2{\mu}g/mL$, respectively. P. silvicola UL6-1 showed a maximum GABA yield of $136.5{\mu}g/mL$ and $200.8{\mu}g/mL$ from S. carnicolor 402-JB-1 when they were cultured for 30 hr at $30^{\circ}C$ in yeast extract-peptone-dextrose medium. The cell-free extract from P. silvicola UL6-1 and S. carnicolor 402-JB-1 showed very high anti-hyperglycemic ${\alpha}$-glucosidase inhibitory activity of 72.3% and 69.9%, respectively. Additionally, their cell-free extract-containing GABA showed the anti-hyperglycemic effect in streptozotocin-induced diabetic Sprague-Dawley rats.

• KSBB Journal
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• v.30 no.4
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• pp.166-174
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• 2015

In this study, an efficient whole cell-based biotransformation for the production of liquiritigenin was developed using Laetiporus sulphureus CS0218 as biocatalyst and aqueous extracts of Glycyrrhiza uralensis as co-substrate, respectively. In order to determine the efficacy of this method, the optimal bioconversion conditions including mycelial growth, three important enzyme activities (${\beta}$-glucosidase, ${\alpha}$-rhamnosidase and ${\beta}$-xylosidase), and apparent viscosity of culture broth were monitored. After optimization, aqueous extracts of G. uralensis were added to the culture medium to directly produce algycone liquiritigenin. By applying this strategy, 67.5% of liquiritin was converted to liquiritigenin at pH 3.0 after 9 days of incubation and finally liquiritigenin was purified from the reaction mixture. And then, their biological activities including anti-oxidant and superoxide dismutase were observed. In fact, purified liquiritigenin was capable of bi-directional functions (i.e., either up-regulation or down-regulation of SIRT1 which is associated with aging). The results indicate that this strategy would be beneficial to produce biologically active liquiritigenin and could be used in pharmaceutical, cosmetic and food applications.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1613-1621
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• 2006

Isolation and identification of algal lytic bacteria were carried out. Nine strains of algal lytic bacteria were isolated by the double-layer method using Anabaena flos-aquae as a sole nutrient. The isolate, AFK-13, showing the highest algal lytic activity was identified as Sinorhizobium kostiense based on the l6S rDNA sequence. The algal lytic experiments of the culture supernatants of AFK-13 demonstrated that the bacterial cell growth reached a maximum at 36-h culture, but the supernatant of 72-h culture exhibited the highest activity. Components among the extracellular products in the crude enzyme of the supernatant from S. kostiense AFK-13 culture were responsible for degradation of cell walls of Anabaena flos-aquae. Algal lytic assay tests of the culture supernatants suggest that the main substances for algal lytic activity could be proteinaceous. The activity of glucosidase was observed highly by polysaccharolytic analysis using the crude enzyme from S. kostiense AFK-13, whereas activities of galactosidase, mannosidase, rhamnosidase, and arabinosidase were also detected in low levels. The molecular weights (MW) of ${\alpha}-\;and\;{\beta}$-glucosidases were estimated to be approximately 50-100 kDa by the ultrafiltration method.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.180-185
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• 2012

Type 2 Diabetes Mellitus, a chronic metabolic disorder which results from a high blood glucose level, is one of the most prevalent and costly diseases of our time. Considering increasing rates of obesity and the aging population in Korea, the number of diabetic patients is likely to rise rapidly in the future. There are five conventional diabetic drugs which work through different mechanisms; sulfonylureas, biguanide, meglitinide, alpha-glucosidase inhibitors, and thiazolidinedione. Although they all have antidiabetic effects, some side effects such as hypoglycemia, weight gain and gastrointestinal intolerance are associated with them. Incretin based therapies, utilizing glucagon-like peptide-1 (GLP-1) and dipeptidyl peptidase-4 (DPP-4) inhibitors, which have a lower risk of adverse side effects, have recently been introduced. At present PPAR-targeting drugs are being actively developed. In this research review, particular emphasis has been placed on the current trends and possible biological targets for the new generation of antidiabetic drugs.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.401-407
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• 2014

Quorum sensing and the stringent response are well-known regulation systems for the expression of virulence genes in enterohemorrhagic Escherichia coli (EHEC). However, how these two systems interact is not well known. E. coli strains with mutations in two regulation systems, ${\Delta}luxS$ (ECM101) and ${\Delta}luxS{\Delta}relA{\Delta}spoT$ (ECM201), and the ${\Delta}luxS$ complement strain to ECM201 (ECM202) were created from EHEC O157:H7 EDL933 to investigate how the regulatory systems interact. The phenotypic changes of the mutant strains were characterized and compared with the wild type. The mutant strains exhibited no obvious growth defects, although acid resistance and cellular cytotoxicity were decreased significantly in all the mutant strains. Phenotypic characterization revealed that mutations in the stringent response system (ECM201 and ECM202) influenced the metabolic (defective utilization of arabinose and L-sorbose) and enzymatic activities (decreased trypsin activity, and increased ${\alpha}$-glucosidase activity). In contrast, the quorum sensing system mutant (ECM101) did not display these phenotypes. The motility of the quorum sensing system mutant (ECM101) was unchanged, but mutation in the stringent response system influenced the motility. Our results suggest that quorum sensing interacts with the stringent response regulation system.

• Preventive Nutrition and Food Science
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• v.9 no.3
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• pp.199-205
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• 2004

The effect of chitosan on enzymatic activities and on bioactive compounds was characterized during germination at $25^{\circ}C$ for 7 days to search for a method to produce a germinated black rice. The germination rate was reduced by the addition of lactate and chitosan. The rotting rate was greatly decreased by chitosan, suggesting that the addition of chitosan into a germination solution might be an effective method for controlling fungal contamination during the germination of cereals. The addition of 100 and 200 ppm chitosan increased $\alpha$-amylase activity after 7 days by up to 152 % and 197 %, respectively. The activities of $\beta$-amylase and $\beta$-glucosidase were lower with 200 ppm chitosan than in distilled water and 100 ppm lactate. The amount of total soluble phenolics and total flavonoids decreased rapidly for four days and thereafter remained constant until the seventh day. The antioxidant activity of germinated black rice, in terms of hydrogen-donating activity, increased slowly and did not correspond to the changes of total soluble phenolics and total flavonoids. The amount of phytic acid was reduced by the addition of 200 ppm chitosan compared to distilled water, indicating that chitosan could be used as an elicitor for the increase of phytase activity during the germination of black rice.

• Nutrition Research and Practice
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• v.12 no.6
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• pp.469-478
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• 2018

BACKGROUND/OBJECTIVES: Mulberry leaf (ML) has been shown to have an inhibitory effect on ${\alpha}$-glucosidase, and suppresses postprandial hyperglycemia, which may be related to its deoxynojirimycin (DNJ) content. This study was conducted to investigate the hypoglycemic and dyslipidemic effects of rice coated with ML rich in DNJ in a type 2 diabetes mouse model. MATERIALS/METHODS: The mice were divided into four groups (n = 8 each): non-diabetic normal control (NC); diabetic control (DM-C), fed with 10% polished rice powder (DM-R); and fed with 10% polished rice powder coated with DNJ-rich ML (DM-DNJR). RESULTS: Supplementation with DNJR for six weeks decreased levels of fasting blood glucose, plasma insulin, triglyceride, total cholesterol, and blood glycosylated hemoglobin; conversely, levels of glucagon-like peptide-1 and high-density lipoprotein-cholesterol showed an increase in the same treatment. In addition, weights of mesenteric, epididymal, and total adipose tissues decreased with DNJR supplementation, when compared with diabetic control db/db mice, while maltase, lactase, and sucrase activity in the small intestine were inhibited. The anti-diabetic effects were marginally greater in the DM-DNJR group than in the DM-R group. CONCLUSIONS: These results suggest that rice coated with ML rich in DNJ can reduce hyperglycemia and hyperlipidemia in db/db mice, and may prove useful for individuals with diabetes.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.926-933
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• 2023

Aspergillus oryzae KCCM 11372 was used to enhance the production of β-glucan using humidity control strategies. Under conditions of 60% humidity, solid-state fermentation (SSF) increased the yields of enzymes (amylase and protease), fungal biomass (ergosterol), and β-glucan. The maximum concentrations obtained were 14800.58 U/g at 72 h, 1068.14 U/g at 120 h, 1.42 mg/g at 72 h, and 12.0% (w/w) at 72 h, respectively. Moreover, the β-glucan containing fermented brown rice (β-glucan-FBR) extracts at concentrations of 25-300 ㎍/ml was considered noncytotoxic to 3T3-L1 preadipocytes. We then studied the inhibitory effects of the extracts on fat droplet formation in 3T3-L1 cells. As a result, 300 ㎍/ml of β-glucan-FBR extracts showed a high inhibition of 38.88% in lipid accumulation. Further, these extracts inhibited adipogenesis in the 3T3-L1 adipocytes by decreasing the expression of C/EBPα, PPARγ, aP2, and GLUT4 genes.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.3
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• pp.451-459
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• 2015

Raw-red bean (RR) should be boiled in hot water, and only boiled-red bean (BR) has been used in the food industry. In the course of development of functional food using red- bean (Phaseolus radiatus L), hot- water extracts (HWEs) of RR and BR were prepared, respectively and their components and various biological activities were compared. The extraction yield at $100^{\circ}C$ of RR (16.2%) was higher than that of BR (14.8%), and contents of total polyphenols, total flavonoids and reducing sugars of HWE of RR were 2.5-fold, 2.1-fold and 1.5-fold higher than those of HWE of BR. In anti-oxidation activity assay, scavenging activities against DPPH anion and ABTS cation as well as reducing power of RR was higher than those of BR. The results suggest that the anti-oxidant compounds in red bean might be heat-liable or discarded during boiling in hot-water as a cooking drip. Unexpectedly, nitrite scavenging activity was stronger in HWE of BR than RR. In anti-microbial activity assay, HWE of RR ($500{\mu}g/disc$) showed growth inhibition activity against gram-positive bacteria, whereas HWE of BR did not show any activity against any tested bacteria and fungi. Assay of in-vitro anti-diabetes and anti-thrombosis activities, which were previously reported in ethanol extract of red-bean, revealed that HWEs of RR and BR did not show significant activities against ${\alpha}$-amylase, ${\alpha}$-glucosidase, thrombin, prothrombin, or blood coagulation factors. Our results suggest that the anti-oxidation, anti-diabetes and anti-thrombosis activities of HWEs of RR and BR were lower than those of ethanol extracts of red bean, and bioactive substances in RR were destroyed during boiling or discarded after boiling. Further research on suitable boiling and re-use of cooking drip of red bean is necessary.

• Journal of Applied Biological Chemistry
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• v.60 no.2
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• pp.101-108
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• 2017

The phenolic contents which were extracted with water and 70% ethanol from O. undulatifolius were 7.7, 10.1 mg/g, respectively. The 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity of water and ethanol extracts were 78, 82% at $50{\mu}g/mL$ phenolics, respectively. The 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization activity were 92, 76% at $100{\mu}g/mL$ phenolics. Antioxidant protection factor in water and ethanol extracts at $200{\mu}g/mL$ phenolics were 1.51 and 2.08 PF, respectively. Thiobarbituric acid reactive substance were 84% in water extracts and 99% in ethanol extracts at $50{\mu}g/mL$ phenolics, respectively. The inhibition activity on ${\alpha}-Glucosidase$ was 44% in ethanol extracts at $200{\mu}g/mL$ phenolics. The inhibition activity on ${\alpha}-amylase$ was 37-88% in water extracts at $50-200{\mu}g/mL$ phenolics. The tyrosinase inhibition activity as whitening effect were 82% in ethanol extracts. The elastase inhibition activity were 4, 61% in water and ethanol extracts, respectively. The collagenase inhibition activity of antiwrinkle effect showed an excellent wrinkle improvement effect as 39% in water extracts and 67% in ethanol extracts at $200{\mu}g/mL$ phenolics, respectively. The hyaluronidase inhibition activity as anti-inflammation effect of ethanol extracts was confirmed to 46% of inhibition at $200{\mu}g/mL$ phenolic. The astringent effect of water and ethanol extracts was confirmed to 13, 32% of effect at $200{\mu}g/mL$ phenolic, respectively.