• Journal of Life Science
• /
• v.25 no.8
• /
• pp.870-879
• /
• 2015

The objective of this research was to evaluate the inhibitory activities of phenolic compounds isolated from mulberry (Morus alba) leaves of 109 types against α-amylase and α-glucosidase. The inhibitory activity of the water extracts from Morus alba cv. Kuksang against α-amylase and α-glucosidase were determined as 93.8% and 48.7% respectively. The total phenolic content of extracts from Morus alba cv. Kuksang was 9.7±0.2 mg/g soluble in water and 14.3±0.2 mg/g soluble in ethanol. The inhibitory activity of the water extracts from Morus alba cv. Kuksang at 200 μg/ml phenolics concentration against α-amylase and α-glucosidase were determined as 100% and 82.6% respectively. The purification of inhibitory compounds was carried out by Sephadex LH-20 and MCI-gel CHP-20 column chromatography using a gradient elution procedure by nomal phase type (EtOH→distilled water) and reverse phase type (distilled water→MeOH). The quercetin was confirmed to be the chemical structure of the inhibitory compound against α-amylase and α-glucosidase by spectroscopic analysis of FAB-MS, NMR and IR spectrum.

• Journal of Applied Biological Chemistry
• /
• v.65 no.1
• /
• pp.75-79
• /
• 2022

Antioxidant, α-glucosidase inhibition, and anticoagulant effects of 80% ethanolic extract from mistletoe (Viscum album var. coloratum) were investigated. The yield and polyphenol content of the mistletoe extract were 30.9±0.4% and 57.6±1.5 mg gallic acid equivalents/g, respectively. The antioxidant effects of the mistletoe extract such as free and cationic radical scavenging ability, nitrite scavenging ability, and reducing power increased in proportion to its concentration. Also the mistletoe extract inhibited the activity of α-glucosidase, and delayed plasma coagulation mainly by inhibiting the extrinsic and common pathways in blood coagulation system.

• Microbiology and Biotechnology Letters
• /
• v.44 no.2
• /
• pp.124-129
• /
• 2016

The extraction and purification of the anti-hyperglycemic α-glucosidase inhibitor from an edible mushroom, Pleurotus cornucopiae, were investigated. The inhibitor was maximally extracted when the P. cornucopiae fruiting body was treated with distilled water at 30℃ for 12 h. Purification was achieved using Sephadex G-100 and G-50 filtration chromatography, pepsin hydrolysis, and reverse-phase HPLC. The compound’s solid yield and inhibitory activity were 12.2% and 9.10 mg/ml of IC₅₀, respectively. The purified inhibitor contained two hexapeptides with Thr-Ile-Ala-Phe-Ile-Asp (A) and Tyr-Tyr-Ala-Ile-Gly-Asp (B) sequences and molecular weights of 678.79 Da (A) and 643.7 Da (B). The purified inhibitor showed a mixed inhibition pattern to α-glucosidase and a dose-dependent anti-hyperglycemic effect in a streptozotocininduced diabetic Sprague-Dawley rat model, exhibited by decreased blood glucose levels at doses of 50 and 300 mg/kg.

• Fisheries and Aquatic Sciences
• /
• v.26 no.3
• /
• pp.181-187
• /
• 2023

The control of intestinal α-amylase and α-glucosidase is an effective therapeutic strategy for prevention of post-prandial hyperglycemia associated with diabetes mellitus. The objective of this study was to evaluate the anti-diabetes activities of Korean edible seaweed against α-amylase and α-glucosidase, two carbolytic enzymes involved in serum glucose regulation. Of the 41 species initially screened, Cladophora wrightiana var. minor, Eisenia bicyclis, Ecklonia cava, Ishige foliacea, and Ishige okamurae exhibited the strongest inhibitory activities from brown seaweeds. Asparagopsis taxiformis showed the strongest inhibitory effects from red seaweeds. The results of this study suggest that the crude brown seaweed extracts (C. wrightiana var. minor, E. bicyclis, E. cava, I. foliacea, and I. okamurae) and crude red seaweed extracts (A. taxiformis) may have beneficial effects suppressing the rise in postprandial hyperglycemia through the inhibition of α-amylase and α-glucosidase.

• The Korean Journal of Food And Nutrition
• /
• v.34 no.3
• /
• pp.289-294
• /
• 2021

The antioxidant activity and α-glucosidase inhibitory activity of the solvent fraction fractionated from the methanol extract of Saururus chinensis Baill were examined. As a result of measuring the yields of methanol, hexane, chloroform, ethylacetate, butanol, and water fractions, the extraction yield of fraction was 18.60, 3.38, 24.03, 7.75, 8.11 and 62.57%, respectively. The total polyphenol content of the methanol extract of Saururus chinensis Baill was 13.40, 4.62, 7.39, 31.24, 25.76 and 5.64 mg GAE/g, respectively. DPPH radical scavenging activity (IC_50%) results were 20.81, 5.47, 10.15, 22.63, 19.68 and 21.06 ug/mL, respectively, and hydroxyl radical scavenging activity (IC_50%) results were 15.81, 2.69, 8.84, 12.80, 3.70 and 3.39 ug/mL. Hydrogen peroxide scavenging activity scavenging activity measurement (IC_50%) showed 33.63, 8.88, 16.93, 32.84, 33.79, and 33.71 ug/mL in methanol, hexane, chloroform, ethyl acetate butanol, and water fractions, respectively. The α-glucosidase inhibitory activity of the solvent fraction fractionated with the methanol extract of 300 sec was measured for the α-glucosidase inhibitory activity of methanol, hexane, chloroform, ethyl acetate butanol, and water fraction, respectively, 15.85, 10.84, 15.74, 24.90, 2.58 and 35.70%.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.2
• /
• pp.174-177
• /
• 2015

A potent α-glucosidase inhibitor (compound I) was isolated from coffee brews by activity-based fractionation and identified as a β-carboline alkaloid norharman (9H-pyrido[3.4-b]indole) on the basis of mass spectroscopy and nuclear magnetic resonance spectra (¹H NMR, ¹³C NMR, and COSY). The norharman showed potent inhibition against α-glucosidase enzyme in a concentration-dependent manner, with an IC₅₀ value of 0.27 mM for maltase and 0.41 mM for sucrase. A Lineweaver-Burk plot revealed that norharman inhibited α-glucosidase enzyme uncompetitively, with a K_i value of 0.13 mM.

• Korean Journal of Clinical Laboratory Science
• /
• v.52 no.4
• /
• pp.398-407
• /
• 2020

The inhibitory effect on α-glucosidase, a marker of postprandial hyperglycemia, and angiotensinconverting enzyme (ACE), a marker of hypertension, was analyzed using non-fermented green tea and three different types of fermented tea, which are popular beverages in modern life. Green tea was mixed with trace amounts of vanadate (50 ㎍/mL), which has insulin-mimetic effects, to investigate the synergistic effect of vanadate on the inhibition of α-glucosidase. The concentration of epigallocatechin gallate (EGCG) and caffeine was also checked. The extracts of green tea and fermented teas showed clear inhibition on α-glucosidase, which caused a decrease in the postprandial glucose levels. The inhibitory effect was most prominent in the 20% fermented tea. Trace amounts of vanadate (50 ㎍/mL)-mixed green tea extract had twice the inhibitory effect on α-glucosidase than the pure tea extract. All teas showed inhibitory effects on ACE. Among those, the effect was most prominent in green tea, which had higher concentrations of EGCG. In contrast, the postprandial glucose-lowering effect and ACE inhibition of the fermented teas, which have a lower level of EGCG, was attributed to some other different functional substances.

• Journal of Dairy Science and Biotechnology
• /
• v.39 no.1
• /
• pp.9-19
• /
• 2021

Enterobacter sakazakii (Cronobacter spp.) causes meningitis, necrotizing enterocolitis, sepsis, and bacteremia in neonates and children and has a high mortality rate. For rapid E. sakazakii detection, various differential and selective media containing α-glucosidase substrates, such as 5-bromo-4-chloro-3-indolyl-α-D-glucopyranoside (BCIG) or 4-methylumbelliferyl-α-D-glucoside (α-MUG), have been developed as only E. sakazakii exhibits α-glucosidase activity in the genus Enterobacter. However, Escherichia vulneris (family: Enterobacteriaceae) can also utilize α-glucosidase substrates, thereby resulting in false positives. Various iron sources are known to promote the growth of gram-negative bacteria. This study aimed to develop a selective medium containing α-glucosidase substrates for E. sakazakii detection that would eliminate false positives, such as those of E. vulneris, and to determine the role of iron source in the medium. Three previously developed (TPD) media, i.e., Oxoid, OK, and VRBG, and the medium developed in this study, i.e., NGTE, were evaluated using 58 E. sakazakii and 5 non-E. sakazakii strains. Fifty-four E. sakazakii strains appeared as fluorescent or chromogenic colonies on all four media that were assessed. Two strains showed colonies on NGTE medium and not on TPD media. In contrast, the remaining two strains showed colonies on TPD media and not on NGTE medium. None of the non-E. sakazakii strains showed fluorescent or chromogenic colonies on any of the evaluated media except E. vulneris, which showed colonies on TPD media and not on NGTE medium. This study demonstrated that the newly developed NGTE medium was not only equally efficient in promoting the growth of bacterial colonies when compared with the currently available media but also eliminated false positives, such as E. vulneris.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.33 no.1
• /
• pp.24-30
• /
• 2016

1-Deoxynojirimycin (DNJ) have been extensively investigated for their α-glucosidase inhibitor on postprandial hyperglycemia, and applied in nutraceuticals and medicine for preventing or delaying progression of type 2 diabetes. However, the amount of DNJ in mulberry leaves is low (about 0.1%), therefore, more effective extraction method is needed. This study was performed to develop microbial DNJ for biological methods of DNJ as an alternative to the chemical methods. In this study, we obtained evidence for Bacillus subtilis that produce DNJ in large quantities by high performance liquid chromatography. Inhibition of α-glucosidase activity was determined to DNJ production or non-production. Investigation of the effect of mulberry leaves powder concentration (1~5%), using the DNJ high-production bacteria, provided evidence for microbial mass production of DNJ. When the 4% mulberry leaf powder for 9 days was used, the α-glucosidase inhibitory activity was over the 85%. Also, the results presented in this study confirm DNJ yield's increasement in microbes using the various of nutrients and provide insight of ways to improve DNJ yields in microorganisms.

• Journal of Applied Biological Chemistry
• /
• v.64 no.2
• /
• pp.121-125
• /
• 2021

Antioxidative, anticoagulant, and α-glucosidase inhibitory effects of 60% (v/v) ethanolic extract from lotus (Nelumbo nucifera) leaves were investigated in vitro. The yield and polyphenol content of the lotus leaves extract were 35.3±1.1% and 186.2±5.2 ㎍ gallic acid equivalents/mg, respectively. The lotus leaves extract effectively scavenged free and cation radicals, and nitrite in a concentration-dependent manner, and possessed potent reducing power. The lotus leaves extract had remarkable anticoagulant and α-glucosidase inhibitory activities as a function of the extract concentration.