• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2222-2226
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• 2011

Amylase is a digestive enzyme that catalyses the starch into sugar. It has been reported that the green tea flavonoid (or polyphenols) (-)-epigallocatechin 3-gallate (EGCG) inhibits human salivary ${\alpha}$-amylase (HSA) and induced anti-nutritional effects. In this study, we performed docking study for seven EGCG-like flavonoids and HSA to understand the interaction mechanism of HSA and EGCG and suggest new possible flavonoid inhibitors of HSA. As a result, EGCG and (-)-epicatechin gallate (ECG) bind to HSA with complex hydrogen bonding interactions. These hydrogen bonding interactions are important for inhibitory activity of EGCG against HSA. We suggested that ECG can be a potent inhibitor of HSA. This study will be helpful to understand the mechanism of inhibition of HSA by EGCG and give insights to develop therapeutic strategies against diabetes.

• Journal of Life Science
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• v.24 no.6
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• pp.633-641
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• 2014

This study investigated the antioxidant and antiobesity activity of extract powders from the following natural color resources: Polygonum indigo, Black locust, Cochineal, Catechu, Grape, Tesu flower, Henna, Chrysanthemum, Sandalwood Red, Himalayan Rhubarb, and Madder. Total phenol content was the highest in Catechu extract, at 348.25 mg/g. DPPH, ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP) were also higher in Catechu extract. Bleaching inhibition activity in the ${\beta}$-carotene linoleic acid system was the highest in Black locust extract, as was ${\alpha}$-Glucosidase inhibition activity. ${\alpha}$-Amylase inhibition activity was the highest in Catechu extract. Trypsin inhibition activity of Black locust extract was greater than 60%, and ${\alpha}$- chymotrypsin inhibition activity of Catechu extract was greater than 40%. Lipase inhibition activity was the highest Black locust extract, at 52.73%. Viability of 3T3-L1 cells was not affected by treatment with extracts at concentrations of $1.25{\sim}25{\mu}g/ml$. Lipid accumulation in the 3T3-L1 cells was the lowest following treatment with Catechu extract, at 55.8%, and this extract also inhibited adipocyte differentiation. These results suggest that the Catechu and Black locust extracts have high antioxidant and antiobesity activities and can be useful ingredients in functional foods.

• Journal of Life Science
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• v.18 no.7
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• pp.1005-1010
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• 2008

In this study, we investigated the inhibitory effect of four solvent fractions of Alnus firma on ${\alpha}-amylase$, ${\alpha}-glucosidase$ and aldose reductase activities. The inhibitory test showed that methanol (MeOH) extract and hexane (HX) fraction strongly inhibited pork pancreatin and salivary ${\alpha}-amylase$ activity. The MeOH extract and HX fraction of Alnus firma at the concentration of 4 mg/ml inhibited more than 70% of pancreatin and salivary ${\alpha}-amylase$ activity. The inhibitory effect of fractions has different specificities against ${\alpha}-amylase$ from pancreatin and salivary. In addition, the MeOH extract and butanol (BuOH) fraction showed the highest inhibitory activity on yeast ${\alpha}-glucosidase$ at values of $IC_{50}$ $137.36\;{\mu}g/ml$ and $115.14\;{\mu}g/ml$ respectively. The MeOH extract and BuOH fraction showed the highest inhibitory activity on yeast ${\alpha}-glucosidase$ than commercial agent such as 1-deoxynorjirimycin and acarbose. Inhibition kinetics of solvent fractions showed that ${\alpha}-glucosidase$ has been inhibited noncompetitively by the MeOH, EA and BuOH fraction. The aldose reductase from human muscle cell had been inhibited strongly by the MeOH extract and EA fraction at 57.996% and 83.293% at the concentration of $50\;{\mu}g/ml$, respectively. These findings may contribute to biological significance in that ${\alpha}-amylase$, ${\alpha}-glucosidase$ and aldose reductase inhibitory compounds could be used as a functional food and a drug for the symptomatic treatment of antidiabetic disease in the future.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.7
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• pp.1079-1085
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• 2013

This study investigated how different amounts of omija fruit (Schisandra chinensis) juice concentrate (0~5%) in sauces affect perceived sensory and quality characteristics. Sauce samples were subjected to chemical analysis for different quality parameters such as Brix, reducing sugars, total phenolic compounds, alpha-amylase inhibition, and alpha-glucosidase inhibition activity. A decrease in pH values was observed with increasing concentrate percentage. As for color, the more concentrate added, the more the L value decreased and other values ($a^*$, $b^*$ and ${\Delta}E$ values) increased. Hypoglycemic effect, as determined by alpha-glucosidase, valuably increased in 4% juice concentrate. As the percentage of concentrate increased, the chemical component values also increased. Significant differences were observed between sauce samples in the sensory evaluation, with the highest overall acceptance being sauce containing 4% juice concentrate. When evaluated with marinated chicken breasts, sauce containing 5% juice concentrate achieved the maximum score.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.7-12
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• 1994

One bacterial strain, that had made the largest inhibition zone at the antagonism assay and also that lost the inhibition activity by the protease treatment, was isolated from raw milk. That strain was identified as Streptococcus salivarius subsp. thermophilus. The specific growht rate of this strain was maximum at 45$\circ $C. However, at this temperature the strain produced no bacteriocin. The bacteriocin activity was quite stable even at high temperature. Moreover, the activity of the vacteriocin was sensitive to proteases. but not to $\alpha $-amylase, DNase I, or RNase.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.8
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• pp.1079-1085
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• 2011

We investigated the biological activities of extracts from the flowers of Angelica gigas Nakai. The $IC_{50}$ of the DPPH radical scavenging activity was 3,535 and 105.0 ${\mu}g/mL$ in the water and ethanol extracts, respectively, whereas it was 12.7 ${\mu}g/mL$ for ascorbic acid. The results showed that the total polyphenol content of the ethanol extracts (48.43${\pm}$0.18 mg/g) was higher than that of the water extracts (39.03${\pm}$0.69 mg/g). The flavonoid content of the ethanol extracts (67.02${\pm}$4.38 mg/g) was higher than that of the water extracts (50.32${\pm}$1.24 mg/g). The ethanol extract showed a 34.45% lower ${\alpha}$-glucosidase inhibition activity than that for acarbose. The ethanol extract showed a 23.62% lower ${\alpha}$-amylase inhibition activity compared with that for acarbose. The water extract showed 16.76% lower pancreatic lipase inhibition activity. Anti-cancer and anti-inflammatory activity was also lower. These results suggest that the flower of Angelica gigas Nakai may be useful as an anti-oxidative agent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.8
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• pp.989-994
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• 2007

This study was designed to investigate whether Sasa borealis leaves extracts (SLE) may inhibit yeast ${\alpha}-glucosidase$ and ${\alpha}-amylase$ activities and postprandial hyperglycemia in STZ-induced diabetic mice. Freeze-dried SLE was extracted with 70% methanol and followed by a sequential fractionation with dicholoromethan, ethylacetate, butanol, and water. Both ethylacetate and butanol fractions showed high inhibitory activities against the ${\alpha}-glucosidase$ and ${\alpha}-amylase$ enzymes. The $IC_{50}$ of ethylacetate and butanol fractions against ${\alpha}-glucosidase$ were 0.54 and 0.63 mg/mL, respectively, indicating a greater inhibition effect than acarbose (0.68 mg/mL) (p<0.05). Likewise, the two fractions exhibited a smaller $IC_{50}$ against ${\alpha}-amylase$, compared with acarbose (p<0.05). However, the yield of ethylacetate fraction of SLE was relatively small. Postprandial blood glucose testing of normal mice and STZ-induced diabetic mice by starch soln. loading (2 g/kg B.W.) showed that postprandial blood glucose level at 30, 60, and 120 min were markedly decreased by single oral administration of SLE butanol fraction (200 mg/kg B.W.) in both normal (p<0.0l) and diabetic mice (p<0.0l). Furthermore, the incremental area under the curve (AUC) was significantly lowered via SLE administration (5,745 versus 12,435 $mg{\cdot}mim/dL$) in the diabetic mice (p<0.0l). The incremental AUC in normal mice corroborated the hypoglycemic effect of SLE (p<0.0l) found in the diabetic mice. These results suggest that SLE may delay carbohydrate digestion and thus glucose absorption. In addition, SLE may have the potential to prevent and treat diabetes via its ability on lowering postprandial hyperglycemia.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.8
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• pp.957-964
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• 2008

Antioxidative, antidiabetes, antibacterial, anticancer and angiotensin-converting enzyme (ACE) inhibitory activities of methanol extracts of dried persimmon, fresh persimmon and persimmon leaves were investigated. Total polyphenol content of dried persimmon, fresh persimmon and persimmon leaves were 147.79, 301.45 and $315.90\;{\mu}g/mg$, respectively, of which fresh persimmon and persimmon leaves had significantly higher total polyphenol than dried persimmon. Activities of DPPH radical scavenging, lipid peroxidation inhibition and salivary $\alpha$-amylase inhibition were increased in persimmon leaves related to total polyphenol contents. Anticancer activities against AGS of fresh persimmon and persimmon leaves were $65{\sim}70%$; however, there were no significant differences between dried persimmon and fresh persimmon on free radical scavenging activity and inhibitory activity of salivary $\alpha$-amylase. Also, extracts of dried persimmon, fresh persimmon and persimmon leaves showed good ACE inhibitory activities. Dried persimmon and fresh persimmon showed antibacterial activities on E.coli O157:H7. Therefore, there are many difference activities by dried and parts of persimmon. From this result, it is suggested that persimmon leaves is believed to have possible antioxidative, antidiabetes and anticancer capacities by polyphenol, but further studies on the identification of the active compound(s) as antioxidant, antidiabetic, antihypertensive and antibacterial materials will be needed to develop a better understanding of its potency on persimmons.

• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.375-381
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• 2022

The purpose of this study was to evaluate the quality characteristics and biological activities of Rosa multiflora Thunberg fruit extracts fermented with Lactobacillus plantarum based on fermentation period of 0, 24, 48, and 72 h. The study showed the pH of Rosa multiflora Thunberg fruit fermentation extracts have decreased as fermentation time increased, but the sugar content remained the same. The total acid content increased as the fermentation time increased. The viable cell count was at highest at 24 h (8.59 log CFU/mL) of fermentation, and the viable cell count decreased as the fermentation time increased. The total polyphenol content (14.85 mg GAE/g), total flavonoid content (6.74 mg RE/g), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, ABTS⁺ radical scavenging activity, reducing power, α-glucosidase and α-amylase inhibitory activity were highest at 24 h of fermentation. Therefore, the study proved fermentation of Rosa multiflora Thunberg fruit with lactic acid increases physiological activity compared to nonfermented Rosa multiflora Thunberg fruit. Also the 24 h of fermentation had the highest activity, confirming the possibility of future use as a functional food material.

• Journal of the Korean Dietetic Association
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• v.25 no.4
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• pp.281-294
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• 2019

The objective of this study was to develop fermented vegetable juices that possess antidiabetic and antioxidant activities. Lactobacillus plantarum MKHA15 (MKHA15) and Leuconostoc mesenteroides MKSR (MKSR) were applied to ferment onion, cabbage, and tomato juices at $37^{\circ}C$ and $30^{\circ}C$ for 72 h, respectively, and their functionality was tested using the 12 h hour-fermented juice by MKHA15, and 48 h hour-fermented juice by MKSR. Inhibition of ${\alpha}$-glucosidase activity was observed in all fermented juices. The onion juice fermented by MKHA15 showed significantly higher ${\alpha}$-glucosidase inhibition activity compared to other juices. All juices showed more than 70% inhibition of ${\alpha}$-amylase activity. The DPPH radical scavenging activity of onion juice fermented by MKSR showed significantly lower activity than cabbage and tomato juices; however, no difference was observed between the types of starter cultures. The SOD-like activity of cabbage juice fermented by MKSR was the highest among the fermented juices. The juices fermented by MKHA15 showed higher reducing power than those by MKSR. Therefore, we believe that cabbage, onion and tomato juice fermented by MKHA15 and MKSR would be useful in probiotic juices, as they possess antidiabetic and antioxidant activities.