• Preventive Nutrition and Food Science
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• v.20 no.2
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• pp.94-101
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• 2015

Grape products have been known to exert greater antioxidant and anti-obesity than anti-hyperglycemic effects in animals and humans. Omija is used as an ingredient in traditional medicine, and it is known to have an anti-hyperglycemic effect. We investigated whether the combined extracts of grape pomace and omija fruit (GE+OE) could reduce fat accumulation in adipose and hepatic tissues and provide beneficial effects against hyperglycemia and insulin resistance in type 2 diabetic mice. C57BL/KsJ-db/db mice were fed either a normal control diet or GE+OE (0.5% grape pomace extract and 0.05% omija fruit extract, w/w) for 7 weeks. GE+OE decreased plasma leptin and resistin levels while increasing adiponectin levels and reducing the total white adipose tissue weight. Furthermore, GE+OE lowered plasma free fatty acid (FFA), triglyceride, and total-cholesterol levels as well as hepatic FFA and cholesterol levels. Hepatic fatty acid synthase and glucose 6-phosphate dehydrogenase activities were decreased in the GE+OE group, whereas hepatic ${\beta}$-oxidation activity was increased. Furthermore, GE+OE supplementation not only reduced hyperglycemia and pancreatic ${\beta}$-cell failure but also lowered blood glycosylated hemoglobin and plasma insulin levels. The homeostasis model assessment of insulin resistance levels was also decreased and the decrease seems to be mediated by the lowered activities of hepatic glucose-6-phosphatase and phosphoenolpyruvate carboxykinases. The present data suggest that GE+OE may have the potential to reduce hyperglycemia, insulin resistance, and obesity in patients with type 2 diabetes.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.701-707
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• 2007

Anti-diabetic effect of Platycodi radix (PR) extract fractions was determined if vitro by investigating insulin-like action, insulin sensitizing action, glucose-stimulated insulin secretion, gene expression related to ${\beta}-cell$ function and mass, and ${\alpha}$-glucoamylase suppressing action. Insulin-like activity was not promoted by the treatment of PR methanol factions in 373-L1 fibroblast. However, treatment with 0, 20 and 100% PR methanol fractions along with 1 ng/mL insulin increased insulin-stimulated glucose uptake in 373-L1 adipocytes. In addition, the treatment of 0% and 100% methanol fractions along with differentiation inducers significantly increased the differentiation of 373-L1 fibroblasts to adipocytes. These fractions may contain insulin sensitizer. The 20%, 80% and 100% methanol fractions enhanced glucose-stimulated insulin secretion in Min6 cells, insulin secreting cell line. This was related to the mechanism to promote glucose sensing and ${\beta}-cell$ proliferation, which was regulated by the induction of IRS-2, glucokinase and PDX-1 genes. As expected, 20, 80 and 100% methanol fractions increased mRNA levels of IRS-2, glucokinase and PDX-1 genes. However, PR fractions did not affect the ${\alpha}-glucoamylase$ activity in vitro. These data suggested that PR extract fractions have anti-diabetic actions through improving insulin sensitization, glucose-stimulated insulin secretion, and ${\beta}-cell$ proliferation. Therefore, PR extracts can be beneficial for anti-diabetic treatment in lean diabetic patients.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.821-826
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• 2005

Postprandial hyperglycemia plays an important role in the development of type 2 diabetes and complications associated with the disease such micro-and macro-vascular disease. The present study investigated the effect and action mechanism of a ethanolic extract from the Schizandra chinensis(SC-E) on hypeglycemia in vivo and in vitro. In vitro, SE-E demonstrated a potent inhibitory effects on ${\alpha}-amylase$ activity ($IC_{50}$ : 4 ${\mu}g/ml$). Its inhibition on ${\alpha}-amylase$ was determined to be competitive type. Oral administration of SE-E markedly lowered plasma glucose levels in non-fasted streptozotocin induced diabetic rats (45 mg/kg BW). In addition when it was orally administrated to rats with starch (2g/kg BW), SC-E (50 and 100 mg/kg BW) significantly suppressed the increase of blood glucose levels after starch loading . These results suggest that some edible plants merit further evaluation for clinical usefulness as anti-diabetic drugs.

• Korean Journal of Pharmacognosy
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• v.35 no.3 s.138
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• pp.203-206
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• 2004

Effects of the EtOH extract from Pelvetia siliquosa on $CCl_4$-induced hepatotoxicity as well as streptozotocin-induced diabetes in rats were investigated. The EtOH extract was found to cause an inhibition of the rise in the transaminase activities in $CCl_4$-intoxicated rats. Also, the EtOH extract exhibited a rat lens aldose reductase inhibition in vitro and showed an inhibition of not only glucose concentrations but also sorbitol accumulations in the lenses, red blood cells and sciatic nerves in the STZ-induced diabetic rats in vivo. These results suggested that this plant might possess hepatoprotective and anti-diabetic activities.

• Preventive Nutrition and Food Science
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• v.5 no.4
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• pp.213-218
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• 2000

The purpose of the study was to investigate the effects of dietary green tea catechin and vitamin E on the phospholipse {TEX}$A_{2}${/TEX} activity and th antioxidative defense system in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100$\pm$10 gm were randomly assigned to one normal and five STZ-induced diabetic groups. The diabetic groups were assigned either a catechin-free diet (DM group), 0.5% catechin diet (DM-0.5C group), 1% catechin diet (DM-1C group), vitamin E-free diet (DM-0E group), and 400 mg vitamin E per kg diet (DM-400E group) according to the levels of dietary catechin or vitamin E supplementation. The vitamin E levels of the normal, DM, DM-0.5C, and DM-1C groups were 40 mg per kg diet. Diabetes was experimentally induced by an intravenous injection of streptozotocin after 4 weeks of feeding the five experimental diets. The animals were sacrificed on the 6th day of he diabetic state. The body weight gains were lower in all five diabetic groups after the STZ injection. The platelet phospholipase {TEX}$A_{2}${/TEX}({TEX}$PLA_{2}${/TEX}) activity in the diabetic groups was higher than that in the normal group. However, the enzyme activity in the DM-0.5C, DM-1C, and DM-400E groups was lower than that in the DM and DM-0E groups. The cytochrome {TEX}$P_{450}${/TEX} and cytochrome {TEX}$b_{5}${/TEX} content and NADPH-cytochrome {TEX}$P_{450}${/TEX} reductase activity were about 50~110% higher in the DM and DM-0E groups than in the normal group, yet significantly reduced by either catechin or vitamin E supplementation. The superoxide dismutase (SOD) content in the liver did not differ significantly in any of the groups. However, the glutathione peroxidase (GSHpx) activity was generally lower in the diabetic groups, compared with the normal group, whereas that of the DM-0.5C, DM-1C, and DM-400E groups was significantly higher compared with that of the DM and DM-0E groups. The levels of thiobarbituric acid reactive substances (TBARS) in the liver tissue were 148% and 201% higher in the DM and DM-0E groups, respectively, compared with the normal group, however, these levels were reduced by either catechin or vitamin E supplementation (DM-0.5, DM-1C and DM-400E). Accordingly, the present results indicate that STZ-induced diabetic rats exhibited an imbalance between free radical generation and scavenger systems in the liver which led to the acceleration of lipid peroxidation. However, these abnormalities were reduced and the antioxidative defense system was restored by either dietary catechin or vitamin E supplementation. In conclusion, the effects of dietary catechin or vitamin E in streptozotocin-induced diabetic rats would appear to inhibit lipid peroxidation as an anti-oxidant by regulating the activity of {TEX}$PLA_{2}${/TEX}.

• Korean Journal of Pharmacognosy
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• v.33 no.4 s.131
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• pp.337-342
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• 2002

The effect of water extract composed of panax ginseng radix rubra, acanthopanacis cortex, and cordyceps (PAC) on diabetic animal models were investigated in two different diabetic animal models. FAC water extract significantly reduced the plasma glucose levels on day 30 as compared with the diabetic control group in $KKA^Y$ obese, hyperglycemic and hyperglycemic and hyperinsulinemic mice, and also reduced the plasma glucose levels as well as total cholesterol in multiple low dose (MLD) strep tozotocin-induced diabetic SD rats. PAC water extract also showed an inhibitory effect on reduction of body weight and on development of MLD STZ-induced diabetic state. Elevated kidney hypertrophy, which is a characteristic feature shown in early stage of diabetic nephropathy and calculated as the ratio of kidney mass (g) relative to the body weight (g), was also markedly improved in PAC water extract- treated group as compared to the diabetic control group. Taken together, these data suggest that PAC water extract may have a potential as a antidiabetic agent in type 2 diabetes mellitus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.11
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• pp.1414-1418
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• 2017

Inhibition of advanced glycation end product (AGE) formation is a valuable therapeutic strategy for the regulation of diabetic complications. This study was conducted to identify potential therapeutic targets of anti-diabetic complications from irradiated mangiferin using AGE formation assay. Radiolytic degradation of the xanthone glucoside mangiferin by gamma-irradiation resulted in three degraded mangiferin analogues: mangiferdiol (1), mangiferinol (2), and isomangiferinol (3). Structures of the three newly generated compounds were characterized by interpretation of nuclear magnetic resonance ($^1H$, $^{13}C$ NMR, $^1H-^1H$ COSY, HSQC, HMBC, and NOESY) and mass spectroscopic data. The anti-diabetic complication of the generated mangiferin derivatives were tested using in vitro AGE formation method. Among the tested degraded products, mangiferinol (2) and isomangiferinol (3) exhibited significantly improved potency against AGE formation inhibitory activities with $IC_{50}$ values of $5.6{\pm}0.8$ and $7.6{\pm}0.9{\mu}M$, respectively. This result implies that xanthone derivatives generated from gamma-irradiated mangiferin might be beneficial for prevention of diabetic complication and related diseases.

• Biomolecules & Therapeutics
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• v.12 no.4
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• pp.215-220
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• 2004

In an attempt to develop new anti-diabetic agents, a series of aryloxypropanolamine derivatives was synthesized to serve as ${\beta}_3$ adrenoceptor agonists. Among these derivatives, 1-{1-methyl-3-[4-(2-methyl-2H-1,2,3,4-tetrazol-5-yl)phenyl]propylamino}-3-phenoxy-2-propanol (KR60886) possessed a high affinity for the ${\beta}_3$ adrenoceptor (Ki = 28 nM) and moderate affinities for ${\beta}_1$ and ${\beta}_2$ adrenoceptors (Ki = 95 nM and 100 nM, respectively). In addition, KR60886 stimulated cAMP production with an EC$_{50}$ of 0.4 ${\mu}M$, confirming its agonistic activity for the ${\beta}_3$ adrenoceptor. In vivo activities of KR60886 were examined by using a fat-fed/streptozotocin (STZ)-treated rat model and the ob/ob mouse model. Oral administration of KR60886 (10 mg/kg) for 3 days (b.i.d.) to fat-fed/STZ-treated rats significantly lowered plasma glucose levels and reduced plasma free fatty acid concentrations. Similarly, KR60886 treatment (10 mg/kg/day for 7 d) resulted in a reduction of plasma glucose concentrations in ob/ob mice. The present study suggests that KR60886 is a potent ${\beta}_3$ receptor agonist with in vivo anti-diabetic properties.

• Journal of Life Science
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• v.17 no.11
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• pp.1571-1575
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• 2007

This research was carried out to investigate the effects of Hambag mushroom on the oxidative stress in diabetic rats, Sprague-Dawley. The diabetic rats induced by streptozotocin were fed with hambag mushroom-powder(G. frondosa) for 6 weeks. For the level of oxidative stress in liver and pancreas tissues, it was studied by measuring LPO (lipid oxide) level as an indicator of lipid peroxidation, XOD(xanthine oxidase) as one of important sources for free radicals and the levels of GSH and GST as anti-oxidant systems. Also, as an indicator of liver damaged by oxidative stress, the activities of serum ALT and AST were measured. It was observed that the levels of ALT, AST, LPO and XOD were higher by about two times in both tissues from diabetic rats than in those from control rats. This indicates that the oxidative stress induced by diabetes caused the tissues damages. However, these levels were decreased in the tissues from rats with hambag mushroom-powder. Futhermore, the activity of GST were higher in both tissues from diabetic rats fed with hambag mushroom-powder than in those from diabetic rats. Thus, it is considered that the hambag mushroom-powder decreases the level of oxidative stress by increasing activity of anti-oxidant system such as GSH and GST. It is suggested that the hambag mushroom-powder can be useful for preventing the tissues damaged by diabetes-induced oxidative stress.

• Journal of Life Science
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• v.33 no.10
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• pp.783-790
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• 2023

Modern people have an increased incidence of metabolic diseases due to changed eating habits, and diabetes is considered the most significant metabolic disease. Given that existing diabetes treatments are accompanied by side effects, the aim of this study was to identify traditional natural products that have anti-diabetic activity. The potential anti-diabetic and antioxidant activities of natural products were examined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, α-glucosidase assay, and protein tyrosine phosphatase 1B (PTP1B) inhibition assay. Methanol extracts of Ulmus davidiana var. japonica, Acer tegmentosum branches, Nelumbo nucifera seeds, and Carthamus tinctorius seeds were found to have high anti-diabetic activity and further fractionated with solvents using ethyl acetate and butanol. Consequently, the ethyl acetate fraction of C. tinctorius seeds (MG-11-E) with high α-glucosidase and PTP1B inhibitory activity was selected. MG-11-E was subjected to preparative thin layer chromatography, and fraction #6 showed high α-glucosidase and PTP1B inhibitory activity. Fraction #6 was analyzed and fractionated via high performance liquid chromatography with 50% methanol as the mobile phase, and anti-diabetic activity was observed in the sample that eluted after 4 min as a single peak. The α-glucosidase inhibitory activity exhibited by this sample seemed to be greater than the PTP1B inhibitory activity; thus, it was concluded that a greater anti-diabetic therapeutic effect may be achieved by combining this agent with natural products that inhibit PTP1B activity.