• Biomolecules & Therapeutics
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• v.12 no.4
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• pp.228-234
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• 2004

Brazilin shows hypoglycemic effect in diabetic animals through enhancement of glucose metabolisms in insulin responsive tissues. One of the major mechanisms of brazilin to enhance glucose metabolism is stimulation of glucose transport in adipocytes. In this study, the essential molecular moiety of brazilin for the stimulation of glucose transport was investigated. We found that brazilin undergoes a structural change in physiological buffer and produces hydrogen peroxide. Methylation of hydroxyl group of brazilin or addition of catalase along with brazilin resulted in the complete inhibition of brazilin-induced glucose transport in adipocytes. Because hydrogen peroxide increases glucose transport by inhibition of phosphatases, we examined the effect of brazilin on phosphatase activity. Brazilin inhibited phosphatases in a wide range of activity, and protein phosphatase 1 and 2A were also inhibited. These results suggest that the production of hydrogen peroxide by oxidation of catechol hydroxyl group of brazilin mediates glucose transport through inhibition of phosphatases which otherwise decrease glucose transport in adipocytes.

• Advances in Traditional Medicine
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• v.3 no.3
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• pp.129-132
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• 2003

The hypoglycemic and hypolipidaemic effects of fenugreek seeds (Trigonella foenum graecum) are well established. Owing to the wide spread use of the seeds by healthy individuals and by diabetic patients we wanted to test whether the seeds can affect biological systems such as membrane transport function. In the present study fenugreek seed polyphenols were extracted and their effect on erythrocyte membrane-bound sodium-potassium adenosine triphosphatase $(Na^+/K^+-ATPase)$ activity was studied in vitro. Fenugreek seed polyphenols inhibited $Na^+/K^+-ATPase$ in erythrocyte membrane of diabetic and normal subjects. Maximum inhibition was observed at $100\;{\mu}l$ of extract containing 0.75 mM gallic acid equivalents. The uncoupling of membrane ATPases in vitro suggest that polyphenols from fenugreek seeds may possess a positive inotropic effect.

• Archives of Pharmacal Research
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• v.24 no.3
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• pp.214-218
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• 2001

The mechanisms responsible for the antidiabetic activity of both the white ginseng radix (Ginseng Radix Alba, GRA) and the rootlet (Cinseng Radix Palva, GRP) were investigated. After a four week oral administration, the fasting blood glucose levels in the GRA- and GRP-treated groups were lower when compared to the control group. To elucidate the hypoglycemic mechanism(s) of the ginseng radices, glucose absorption from the small intestine, hepatic hexokinase and glucose-6-phosphatase activities, in addition to PPAR-${\gamma}$ expression in adipose tissue were examined. The results strongly suggest that GRA can improve hyperglycemia in KKAy mice, possibly by blocking intestinal glucose absorption and inhibiting hepatic glucose-6-phosphatase, and GRP through the upregulation of adipocytic PPAR-$\gamma$ protein expression as well as inhibiting intestinal glucose absorption.

• Journal of the Korean Chemical Society
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• v.67 no.2
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• pp.99-105
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• 2023

Here we present how a supramolecular complex of Glycyrrhizic acid (GA) with Menthol (Mt) affects the blood glucose levels and glycogen synthesis in the liver of rats in in-vivo experiments with diabetes caused by alloxan. We have shown that Menthol, Glycyrrhizic acid and GA:Mt supramolecular complexes can restore functional dysfunction of the liver mitochondria in alloxan diabetes, i.e., inhibit lipid peroxidation. The hypoglycemic activity and mitochondrial membrane stabilizing properties of the supramolecular complex GA:Mt (4:1) in alloxan diabetes were more pronounced than those of menthol, GA and its GA:Mt (2:1) and GA: Mt (9:1) supramolecular complexes.

• Microbiology and Biotechnology Letters
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• v.25 no.4
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• pp.391-395
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• 1997

It was proved that both ethanol extracts from Mori Folium from Kangwon do and silk worm had higher inhibition acitivity on $\alpha$-glucohydrolase than the water extracts. In adding above 8.5 (mg/L) of silkworm extracts, the inhibition rate on $\alpha$-1,4 glucosidase was saturated while the inhibition rate was continuously increased in adding the extracts from Moli Folium. It was also found that the diethyl ether fraction showed much better inhibition activity than water fraction from ethanol extracts, yielding ca. 85% of inhibition rate for the extract of Moli Folium, compared to 91% for a commercially available hypoglycemic drug, Chloropropamide. In separating the diethyl ether fractions by Consecutive Sephadex gel filtration and Thin layer chromatography, three and four active spots were obtained from Moli Folium and silkworm, respectively. It is interesting that the similar Rf spots from both species among several spots in TLC have the highest inhibition acitivity on a target enzyme, which can imply that the active substances from both species are same or similar molecular weight and structure. Glucose-lowering activities of both speciese were also examined in vivo, showing that the fraction from Moli Folium had better activity than that from silkworm, and its activity was similar to that of a commercial drug.

• Journal of the Korean Wood Science and Technology
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• v.47 no.4
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• pp.498-508
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• 2019

This study was carried out to investigate the potential of Korean red pine (Pinus densiflora) inner bark extracts as an antidiabetic agent. The ethyl acetate soluble fraction of the bark extracts was chromatographed on a Sephadex LH-20 column to yield five compounds, which structures were elucidated by NMR spectroscopy. The isolated compounds were (+)-catehin, (-)-epicatechin, taxifolin, taxifolin-3'-O-${\beta}$-D-(+)-glucose and $\tilde{n}$-courmaric acid. The antidiabetic activity of the different fractions, including the crude extracts and isolated compounds, was evaluated by ${\beta}$-cells insulin secretion and glucose uptake in skeletal muscle cells. The insulin secretion was 128% for taxifolin at $25{\mu}g/mL$. However, the other samples had no effect on this test. For the glucose uptake activity assay, $1{\mu}M$ insulin and 2 mM metformin were used as controls. Both the crude extract and taxifolin showed relatively low activity values, but the other samples yielded glucose uptake values over 260%. ${\rho}$-courmaric acid showed the highest uptake (270%). The results confirmed that Korean red pine extracts may be used as a hypoglycemic agent.

• Journal of Nutrition and Health
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• v.49 no.1
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• pp.18-27
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• 2016

Purpose: Our previous study demonstrated the hypoglycemic effects of mulberry (Morus alba L.) leaf and the underlying mechanisms. Here we explored the potency of mulberry twigs (TW) and root barks (RB) in postprandial hypoglycemic effects in vitro and in vivo. Methods: The major components of TW and RB were determined by high performance liquid chromatography (HPLC). Alpha-glucosidase inhibition and glucose/fructose uptake inhibition in Caco-2 cells were determined for TW, RB, and their major components, followed by an oral sugar tolerance test (OSTT) in streptozotocin-induced diabetic rats. Male Wistar rats were fed a high-fat diet for 2 weeks and then a single dose of streptozotocin (35 mg/kg B.W) was administered by intraperitoneal injection. Rats with fasting blood glucose levels above 126 mg/dL were randomly divided into 5 groups (n = 8/group) for the following treatments by gavage for 4 weeks: vehicle (normal control and diabetic control), 200 mg/kg B.W of TW or RB or 100 mg/kg B.W of oxyresveratrol (OXY). Results: OXY and mulberroside A were identified as the major components of TW and OXY, mongolicin, and kuwanon H for RB. A significant inhibitory activity on ${\alpha}-glucosidase$ was found for TW, RB, and OXY (p = 0.0099). There was a dose-dependent inhibition of TW and RB on the intestinal sugar uptakes in Caco-2 cells, showing a greater impact on fructose compared to glucose. The OSTT showed that TW and RB significantly delayed time to maximal concentration (p = 0.0088) and decreased maximal concentration (p = 0.0043) compared to the control group. Conclusion: These results suggest that TW and RB may have a postprandial hypoglycemic effect, particularly in the case of high fructose or sucrose intake. OXY was suggested as a contributor to the hypoglycemic effect of TW and RB. Further studies are needed for the systemic effect of TW and RB in circulation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.12
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• pp.1761-1768
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• 2010

Hypoglycemic effect through activity inhibition of $\alpha$-glucosidase and $\alpha$-amylase was evaluated using leaves of Eleutherococcus senticosu, Eleutherococcus gracilistylus, Eleutherococcus sieboldianus and Eleutherococcus sessiliflorus which belong to Acanthopanax sessiliflorus genus. As a result of measuring $\alpha$-glucosidase activity inhibition, extract of Eleutherococcus gracilistylus showed around 43.38% of activity inhibition compared with acarbose and extract of Eleutherococcus senticosu showed 41.24% inhibitory effect. As a result of measuring $\alpha$-amylase activity inhibition, acarbose showed 73.25% of activity inhibition in 10 mg/mL concentration, and the extract of Eleutherococcus senticosu leaves showed 91.90% higher activity inhibition compared with acarbose. Also, after subjects in a model were induced diabetes with streptozotocin (STZ) intake plant extract from Acanthopanax sessiliflorus for 2 weeks, effect of improving blood glucose level and fat was examined. In all groups with specimen, Eleutherococcus senticosu (T1), Eleutherococcus gracilistylus (T2), Eleutherococcus sieboldianus (T3) and Eleutherococcus sessiliflorus (T4), blood glucose level was significantly decreased compared with that in control group (C). In an experiment of examining changes in fat concentration in blood, total cholesterol content increased in a control group compared with a normal, while in T1, T3 and T4, it decreased significantly compared with the control group. As for HDL-cholesterol, it significantly increased in all diabetes induced groups compared with the normal group, and in T3, it increased the most significantly by 55.61% compared with the control group. In case of LDL-cholesterol, specific difference between the normal group and the control group was not found; however, significant increase was detected in T2 and T3, whereas in T1 and T4, it decreased significantly compared with the control group. As for triglyceride, its concentration increased in the control group like total cholesterol. It decreased 60.16% in T3, 60.80% in T4 and 50.16% in T1 compared with the control group. As a result of measuring the concentration of triglyceride in extracted liver, the control group showed significant increase compared with the normal group, whereas T1 and T2 showed significant decrease compared with the normal group. The above results show that extracts from Acanthopanax sessiliflorus genus are effective for hypoglycemic and improving fat metabolism due to diabetes.

• Natural Product Sciences
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• v.14 no.2
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• pp.143-146
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• 2008

Protein tyrosine phosphatase 1B (PTP1B) is emerging as a potential therapeutic target for the treatment of type-2 diabetes and obesity. To search for new types of PTP1B inhibitors, we have undertaken in vitro enzyme assay for some anthraquinones and stilbenes isolated from plants. Of the anthraquinones tested, physcion (1), 1-O-methylemodin (2), and emodin (3) showed high activities, with $IC_{50}$ values of 7.6, 7.0, and $3.8{\mu}g/mL$, respectively, while the anthraquinone glycosides, physcion-8-O-${\beta}$-D-glucopyranoside (4) and emodin-8- O-${\beta}$-D-glucopyranoside (5), were less active than their aglycones. All the stilbenens (6 - 15) slightly inhibited PTP1B activity at high concentration of $30{\mu}g/mL$. Our findings suggest that the hypoglycemic effect of anthraquinones may be associated with their PTP1B inhibitory activity.

• Journal of Nutrition and Health
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• v.30 no.1
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• pp.25-31
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• 1997

The effects of Trichosanthes kirilowii Max. subfractions, which has long been used as a wild vegetable and folk medicine, on insulin activity and acute toxicity were investigated. Diabetes melitus was induced in male Sprague-Dawley rats by the injection of streptozotocin(STZ) into the tail vein at a dose of 45mg/kg. The hexane fraction of the plant was subfractioned by silica gel column chromatography and were administered orally for 14 days and the normal and STZ-control group were orally administered with tween 80. The body weight gain was monitored and plasma levels of glucose, cholesterol, triglyceride, free fatty acid HDL-cholesterol were determined. The plasma activities of aspartate aminotransferase(AST) and alanine aminotransferase (ALT) were analysed. The subjraction A of hexane fraction lowered plasma glucose levels significantly and increased insulin activity compared to that of STZ-control. The activities of AST and ALT were decreased by administration of subfractions A and C of hexane fraction. The intakes of the hexane fraction of Trichosanthes kirilowii Max. did not showed the acute toxicity. It is suggested from the results that the subfraction A of the hexane fraction of Trichosanthes kirilowii Max. showed a hypoglycemic effect on diabetic rats and that the subfraction may be beneficial for insulin secreation.