• Bulletin of the Korean Chemical Society
• /
• v.29 no.5
• /
• pp.921-927
• /
• 2008

Discovery of $\alpha$-glucosidase inhibitors has been actively pursued with the aim to develop therapeutics for the treatment of diabetes and the other carbohydrate mediated diseases. As a method for the discovery of new novel inhibitors of $\alpha$-glucosidase, we have addressed the performance of the computer-aided drug design protocol involving the homology modeling of $\alpha$-glucosidase and the structure-based virtual screening with the two docking tools: FlexX and the automated and improved AutoDock implementing the effects of ligand solvation in the scoring function. The homology modeling of $\alpha$-glucosidase from baker’s yeast provides a high-quality 3-D structure enabling the structure-based inhibitor design. Of the two docking programs under consideration, AutoDock is found to be more accurate than FlexX in terms of scoring putative ligands to the extent of 5-fold enhancement of hit rate in database screening when 1% of database coverage is used as a cutoff. A detailed binding mode analysis of the known inhibitors shows that they can be stabilized in the active site of $\alpha$- glucosidase through the simultaneous establishment of the multiple hydrogen bond and hydrophobic interactions. The present study demonstrates the usefulness of the automated AutoDock program with the improved scoring function as a docking tool for virtual screening of new $\alpha$-glucosidase inhibitors as well as for binding mode analysis to elucidate the activities of known inhibitors.

• Journal of Applied Biological Chemistry
• /
• v.65 no.2
• /
• pp.107-111
• /
• 2022

Biological activities such as antioxidant, anticoagulant, and α-glucosidase inhibitory effects of 40% (v/v) ethanolic extract from black locust (Robinia pseudoacacia L.) flower were investigated. The polyphenol content of the black locust flower extract was 39.8±0.5 mg gallic acid equivalents/g. The flower extract represented antioxidant effects such as free radical, cationic radical, and nitrite scavenging abilities as well as reducing power. Also the flower extract inhibited α-glucosidase activity and common pathway in plasma coagulation system.

• Korean Journal of Pharmacognosy
• /
• v.47 no.1
• /
• pp.29-37
• /
• 2016

Anti-diabetic potential of the leaves of A. elata through the inhibitory activity on PTP1B and ${\alpha}$-glucosidase has not been reported. In this study, the EtOAc fraction of methanolic extract from the leaves of A. elata showed potent inhibitory activity against the PTP1B and ${\alpha}$-glucosidase with $IC_{50}$ value of $96.29{\pm}0.3$ and $264.71{\pm}14.87{\mu}g/mL$, respectively. Three known triterpenoids, oleanolic acid, oleanolic acid-28-O-${\beta}$-D-glucopyranoside and oleanolic acid-3-O-${\beta}$-D-glucopyranoside were isolated from the most active EtOAc fraction. We determined the chemical structure of these triterpenoids through comparisons of published nuclear magnetic resonance (NMR) spectroscopic data. Furthermore, we screened these triterpenoids for their ability to inhibit PTP1B and ${\alpha}$-glucosidase over a range of concentrations ($12.5-50{\mu}M$). All three terpenoids significantly inhibited PTP1B in a concentration dependent manner and oleanolic acid effectively inhibited ${\alpha}$-glucosidase. In addition, these compounds revealed potent inhibitory activity with negative binding energies toward PTP1B, showing high affinity and tight binding capacity in the molecular docking studies. Therefore, the results of the present study clearly demonstrate that A. elata leaves and its triterpenoid constituents might be beneficial in the prevention or treatment of diabetic disease.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.21 no.2
• /
• pp.163-167
• /
• 2010

[ $\alpha$ ]Glucosidase (EC 3.2.1.20) is a glycosidase that hydrolyzes disaccharides, oligosaccharides, and polysaccharides resulting in the release of α-D-glucose. In this study, $\alpha$-glucosidase activity in the hemolymph and midgut of the mulberry silkworm Bombyx mori and Japanese oak silkmoth Antheraea yamamai was measured using maltose, sucrose, trehalose, and p-nitrophenyl $\alpha$-D-glucopyranoside as substrates. In general, hemolymph $\alpha$-glucosidase activity was higher in B. mori than in A. yamamai. In contrast, midgut $\alpha$-glucosidase activity was higher in A. yamamai than in B. mori for all of the substrates tested. $\alpha$-Glucosidase activity in the midgut of both B. mori and A. yamamai showed similar responses to changes in pH and temperature for all of the substrates tested. Native (7.5%) PAGE of hemolymph and midgut proteins from B. mori and A. yamamai followed by staining with 4-methylumbelliferyl $\alpha$-D-glucoside (MUG) indicated that the $\alpha$-glucosidases of these related lepidopterans are functionally similar but structurally different. In comparison to $\alpha$-glucosidase activity from A. yamamai, $\alpha$-glucosidase activity from B. mori was generally less sensitive to the $\alpha$-glucosidase inhibitors, 1-deoxynojirimycin (DNJ), acarbose, and voglibose when the activity was determined using maltose, sucrose, and trehalose.

• Korean Journal of Medicinal Crop Science
• /
• v.22 no.4
• /
• pp.289-294
• /
• 2014

Maesa japonica (Thunb.) is an evergreen shrub belonged to the Myrsinaceae family, which was discovered in 2006 in South Korea. And, its biological functions have not been well studied. In this study, we determined the antioxidant activities, ${\alpha}$-glucosidase inhibitory effects and antimicrobial activities of methanol extract and the solvent fractions of M. japonica leaves and twigs. The highest antioxidant activity obtained by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay and reducing power assay was found in the ethylacetate fraction of twigs methanol extract, which contained the highest level of total phenolic compounds compared to the other fractions. In addition, ethylacetate fraction of twigs extract exhibited higher inhibitory activities against ${\alpha}$-glucosidase ($IC_{50}=0.8{\mu}g/m{\ell}$) compared to the $IC_{50}$ of the buthanol fraction ($IC_{50}=16{\mu}g/m{\ell}$) of leaves extract. It showed antimicrobial activities against Bacillus atrophaeus and Bacillus subtilis subsp. Spizizenii. Although the data is too limited, the current study is the first report on biological functions of M. japonica.

• Food Science and Preservation
• /
• v.30 no.2
• /
• pp.358-368
• /
• 2023

Euonymus alatus (Thunb.) Sieb., also known as the arrow tree in Korea, is a plant in East Asia used in traditional medicine and food. In particular, the wings of E. alatus are rich in phenolic compounds. This study evaluated the antioxidant, α-glucosidase inhibition, and anti-cancer activities of E. alatus wing extracts. The radical and hydrogen peroxide scavenging acitvities and reducing the power of 1,000 ㎍/mL E. alatus wing extracts, were similar to those of the positive control (0.1% BHT, 0.1% α-tocopherol). In addition, ethanol and methanol extract at 250 ㎍/mL showed 95.70 and 94.99% of α-glucosidase inhibition activity, respectively. The ethanol extract of E. alatus wings had the highest total polyphenol and flavonoid contents (867.8 mg% and 521.7 mg%, respectively). The E. alatus wing extracts significantly decreased the cell viability of LNCaP human prostate cancer cells (p<0.001), MDA-MB-231 human breast cancer cells (p<0.001), and HT-29 human colon cancer cells (p<0.001) in a dose-dependent manner. However, there was no significant effect on B16 mouse melanoma cells. Notably, the ethanol extracts showed higher cancer cell growth inhibitory activity in LNCaP and HT-29 cells than the other extracts. These results suggest that E. alatus wing extracts could have significant clinical applications, and our results can be used as basic data for future functional food material development.

• Food Science and Preservation
• /
• v.21 no.2
• /
• pp.254-263
• /
• 2014

This study was carried out to analyze the effects of water and 70% ethanol extract on the antioxidative and antidiabetic activities of Smilax china L., a vine shrub belonging to the lily family. The activities of the extracts were measured based on the total phenolic and flavonoid contents and through on the results of the antioxidant tests, such as the electron-donating ability, ABTs radical scavenging activities, SOD-like activity, xanthine oxidase inhibition effect, antioxidant protection factor (PF), TBARs content and ACE inhibition activity, and ${\alpha}$-glucosidase, and ${\alpha}$-amylase inhibition activity. The resulting total phenolic and flavonoid contents of the 70% ethanol extract from S. china L. were greater than those of the water extract from S. china L. With regard to the results of the antioxidant tests, such as the electron-donating ability, ABTs radical scavenging activity, SOD-like activity, xanthine oxidase inhibition effect, antioxidant protection factor (PF), and TBARs content, those from the 70% ethanol extract from S. china L. were greater than those from the water extract from S. china L. Also, with regard to the ACE inhibition effect and ${\alpha}$-glucosidase and ${\alpha}$-amylase inhibition, those from the 70% ethanol extract from S. china L. were greater than those from the water extract from S. china L. All these findings show that the 70% ethanol extract from S. china L. has greater antioxidative and antidiabetic effects and can be used as a preventive agent for oxidation and diabetes.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.4
• /
• pp.405-409
• /
• 2008

This study was performed to investigate the physiological activities of Viola mandshurica. Antioxidant activity was evaluated by measuring total phenolic contents, reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-di-2-ethyl-benzthiazoline sulphonate (ABTS) radical scavenging activity while anti-diabetic activity was measured by inhibition activities on ${\alpha}$-amylase and ${\alpha}$-glucosidase. V. mandshurica extracts were prepared by extracting with four different solvents (methanol, ethanol, acetone, and water). The methanol extract showed the highest total phenol content (34.49 mg/g gallic acid equivalents) among the extracts. The water extract showed the highest reducing power (0.454) at the concentration of $1,000{\mu}g$/mL. The acetone extract showed the most potent radical scavenging activity. DPPH and ABTS radical scavenging activity of the acetone extract at the concentration of $1,000{\mu}g$/mL were 21.13% and 43.53%, respectively. The inhibitory activity of acetone extracts against ${\alpha}$-amylase and ${\alpha}$-glucosidase showed more than 100% at the concentration of $1,000{\mu}g$/mL. The results indicate that V. mandshurica might have potential antioxidant and anti-diabetic activities.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.18 no.4
• /
• pp.1129-1133
• /
• 2004

For the purpose of developing new anti-HIV agents from natural sources, the extracts of Kalopanax pictus were tested for their inhibitory effects on HIV-1 replication and its essential enzymes as the reverse transcriptase (RT). protease and α-glucosidase. In the assay of HIV-1-infected human T-cell line, water extracts of stem and leafstalk inhibited the HIV-1-induced cytopathic effects with Ie (inhibitory concentration) of 25 and 50㎍/㎖, respectively. Moreover water extracts (100㎍/㎖) of stem and leafstalk showed strong activity of 80% and 90% on anti-HIV-1 RT using Enzyme Linked Oligonucleotide Sorbent Assay (ELOSA) method. In the HIV-1 protease inhibition assay, aqueous stem extract inhibited the activity of the enzyme to cleave an oligopeptide, resembling one of the cleavage sites in the viral polyprotein which can only be processed by HIV-1 protease with 58%, but no glucosidase inhibitory activities. We found out this result, for these samples it is possible that the inhibition of the viral replication in vitro is due to the inhibition at least one of RT and protease. It would be of great interest to identify the compounds which are responsible for this inhibition, since all therapeutically useful agent up to date are RT, PR and α-glucosidase inhibitors.

• The Korean Journal of Mycology
• /
• v.44 no.1
• /
• pp.57-60
• /
• 2016

Following preparation of water extracts of Pleurotus cornucopiae fruiting body-containing ${\alpha}$-glucosidase inhibitor, their antihyperglycemic effects were examined using streptozotocin-induced diabetic Sprague-Dawley (SD)-rats. The water extracts from Pleurotus cornucopiae showed dosage-dependant antihyperglycemic effects on the streptozotocin-induced diabetic SD-rats after oral administration to 120 min on the short time test and 4 days on the long time test, respectively. The water extracts from Pleurotus cornucopiae fruiting body showed dosage-dependent hypoglycemic action after administration to 120 min and 4 days in the SD-rat and streptozotocin-induced diabetic SD-rat.