Ha-Neul Choi

Quercetin ameliorates hyperglycemia and dyslipidemia and improves antioxidant status in type 2 diabetic db/db mice.

This study investigated the hypoglycemic, hypolipidemic, and antioxidant effects of dietary quercetin in an animal model of type 2 diabetes mellitus. Four-week-old C57BL/KsJ-db/db mice (n = 18) were offered an AIN-93G diet or a diet containing quercetin at 0.04% (low quercetin, LQE) or 0.08% of the diet (high quercetin, HQE) for 6 weeks after 1 week of adaptation. Plasma glucose, insulin, adiponectin, and lipid profiles, and lipid peroxidation of the liver were determined. Plasma glucose levels were significantly lower in the LQE group than in the control group, and those in the HQE group were even further reduced compared with the LQE group. The homeostasis model assessment for insulin resistance (HOMA-IR) showed lower values for LQE and HQE than for the control group without significant influence on insulin levels. High quercetin increased plasma adiponectin compared with the control group. Plasma triglycerides in the LQE and HQE groups were lower than those in the control group. Supplementation with high quercetin decreased plasma total cholesterol and increased HDL-cholesterol compared with the control group. Consumption of low and high quercetin reduced thiobarbituric acid reactive substances (TBARS) levels and elevated activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the liver. Thus, quercetin could be effective in improving hyperglycemia, dyslipidemia, and antioxidant status in type 2 diabetes.

Cordyceps militaris alleviates non-alcoholic fatty liver disease in ob/ob mice

BACKGROUND/OBJECTIVES Non-alcoholic fatty liver disease (NAFLD) is becoming an important public health problem as metabolic syndrome and type 2 diabetes have become epidemic. In this study we investigated the protective effect of Cordyceps militaris (C. militaris) against NAFLD in an obese mouse model. MATERIALS/METHODS Four-week-old male ob/ob mice were fed an AIN-93G diet or a diet containing 1% C. militaris water extract for 10 weeks after 1 week of adaptation. Serum glucose, insulin, free fatty acid (FFA), alanine transaminase (ALT), and proinflammatory cytokines were measured. Hepatic levels of lipids, glutathione (GSH), and lipid peroxide were determined. RESULTS Consumption of C. militaris significantly decreased serum glucose, as well as homeostasis model assessment for insulin resistance (HOMA-IR), in ob/ob mice. In addition to lowering serum FFA levels, C. militaris also significantly decreased hepatic total lipids and triglyceride contents. Serum ALT activities and tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were reduced by C. militaris. Consumption of C. militaris increased hepatic GSH and reduced lipid peroxide levels. CONCLUSIONS These results indicate that C. militaris can exert protective effects against development of NAFLD, partly by reducing inflammatory cytokines and improving hepatic antioxidant status in ob/ob mice.

Hypoglycemic effects of Welsh onion in an animal model of diabetes mellitus

Tight control of blood glucose is the most important strategy for the treatment of diabetes mellitus. Here, we investigated the beneficial effects of Welsh onion on fasting and postprandial hyperglycemia. Inhibitory activities of hot water extracts from the green stalk and white bulb, which are the edible portions of the Welsh onion, and the fibrous root extract against yeast α-glucosidase were measured in vitro. To study the effects of Welsh onion on postprandial hyperglycemia, a starch solution (1 g/kg) with and without Welsh onion fibrous root extract (500 mg/kg) or acarbose (50 mg/kg) was administered to streptozotocin-induced diabetic rats after an overnight fast. Postprandial plasma glucose levels were measured and incremental areas under the response curve were calculated. To study the hypoglycemic effects of chronic feeding of Welsh onion, five-week-old db/db mice were fed an AIN-93G diet or a diet containing either Welsh onion fibrous root extract at 0.5% or acarbose at 0.05% for 7 weeks after 1 week of adaptation. Fasting plasma glucose and blood glycated hemoglobin were measured. Compared to the extract from the edible portions of Welsh onion, the fibrous root extract showed stronger inhibition against yeast α-glucosidase, with an IC50 of 239 µg/mL. Oral administration of Welsh onion fibrous root extract (500 mg/kg) and acarbose (50 mg/kg) significantly decreased incremental plasma glucose levels 30-120 min after oral ingestion of starch as well as the area under the postprandial glucose response curve, compared to the control group (P < 0.01). The plasma glucose and blood glycated hemoglobin levels of the Welsh onion group were significantly lower than those of the control group (P < 0.01), and were not significantly different from those fed acarbose. Thus, we conclude that the fibrous root of Welsh onion is effective in controlling hyperglycemia in animal models of diabetes mellitus.

α-glucosidase inhibitory activities of myricetin in animal models of diabetes mellitus

The α-glucosidase inhibitory activity of myricetin in vivo was investigated. Streptozotocininduced diabetic rats were administered a starch solution (1 g/kg) with and without myricetin (100 mg/kg) or acarbose (40 mg/kg) after an overnight fast. Myricetin and acarbose alleviated postprandial hyperglycemia conditions, compared with untreated rats. Consumption of 0.08% myricetin or 0.03% acarbose in the diet for 7 weeks significantly (p<0.05) reduced the serum fasting glucose, blood glycated hemoglobin, and maltase activities of the small intestine in db/db mice, compared with controls. Myricetin can be beneficial for control of hyperglycemia in diabetes mellitus partly via inhibition of the a-glucosidase activity.

Renoprotective and antioxidant effects of Saururus chinensis Baill in rats fed a high-fructose diet

This study investigated the preventive effect of Saururus chinensis Baill against renal damage induced by a high-fructose diet in rats. The rats (n = 30) were fed either a cornstarch-based (65%), high-fructose (65%), or high-fructose (64.5%) diet with 0.5% S. chinensis Baill extract for 10 weeks. Twenty-four hour urine collections were obtained and the animals were sacrificed after an overnight fast. Serum urea and creatinine and urine albumin were measured using colorimetric methods, and creatinine clearance was determined. In addition, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), and the activity of superoxide dismutase (SOD) in the kidney were determined. Kidney samples were also examined histologically. The fructose-fed rats showed renal dysfunction, indicated by decreased creatinine clearance, increased albumin in the urine, and increased urea and creatinine in the serum. These renal function parameters were comparable to control levels in rats that consumed S. chinensis Baill. Fructose consumption increased renal TBARS and reduced GSH and SOD activity, whereas these levels were near-normal in the rats consuming S. chinensis Baill. The kidneys of fructose-fed rats showed glomerular basement membrane thickening, mesangial matrix expansion, and tubule dilation. These pathological changes were not seen in the rats that consumed S. chinensis Baill. Therefore, S. chinensis Baill effectively alleviated fructose-induced renal damage in these rats, at least partially due to antioxidant activity.

Chamnamul [Pimpinella brachycarpa (Kom.) Nakai] ameliorates hyperglycemia and improves antioxidant status in mice fed a high-fat, high-sucrose diet.

Chronic consumption of a high-fat, high-sucrose (HFHS) diet increases insulin resistance and results in type 2 diabetes mellitus in C57BL/6J mice. Hyperglycemia in diabetics increases oxidative stress, which is associated with a high risk of diabetic complications. The purpose of this study was to examine the hypoglycemic and antioxidant effects of chamnamul [Pimpinella brachycarpa (Kom.) Nakai] in an animal model of type 2 diabetes. The α-glucosidase inhibitory activity of a 70% ethanol extract of chamnamul was measured in vitro. Five-week-old male C57BL/6J mice were fed a basal or HFHS diet with or without a 70% ethanol extract of chamnamul at a 0.5% level of the diet for 12 weeks after 1 week of adaptation. After sacrifice, serum glucose, insulin, adiponectin, and lipid profiles, and lipid peroxidation of the liver were determined. Homeostasis model assessment for insulin resistance (HOMA-IR) was determined. Chamnamul extract inhibited α-glucosidase by 26.7%, which was 78.3% the strength of inhibition by acarbose at a concentration of 0.5 mg/mL. Serum glucose, insulin, and cholesterol levels, as well as HOMA-IR values, were significantly lower in the chamnamul group than in the HFHS group. Chamnamul extract significantly decreased the level of thiobarbituric acid reactive substances and increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver compared with the HFHS group. These findings suggest that chamnamul may be useful in prevention of hyperglycemia and reduction of oxidative stress in mice fed a HFHS diet.

Antioxidant effect of Phaeodactylum tricornutum in mice fed high-fat diet

High-fat diet (HFD)-induced obesity is associated with oxidative stress. The purpose of this study was to examine the antioxidant effect of Phaeodactylum tricornutum extract in mice with diet-induced obesity. Four-week-old C57BL/6J mice were fed a normal diet or HFD with and without 0.7% P. tricornutum lipid extract corresponding to 0.2% fucoxanthin for 8 weeks. P. tricornutum significantly decreased body weight and epidydimal white adipose tissue in mice fed the HFD. Serum triglyceride, glucose, insulin, and leptin levels, as well as homeostasis model assessment for insulin resistance (HOMA-IR) values, were significantly lower in the P. tricornutum group than in the HFD group. P. tricornutum significantly decreased thiobarbituric acid reactive substances (TBARS) and increased glutathione and the activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver compared with the HFD group. Thus, P. tricornutum could exert antiobesity and antioxidant effects in mice fed a HFD.

Effect of Dongchunghacho (Cordyceps militaris) on hyperglycemia and dyslipidemia in type 2 diabetic db/db mice

Controlling hyperglycemia and dyslipidemia is associated with reduced risks for diabetic complications. The present study examined the effect of dongchunghacho (Cordyceps militaris; CM) on hyperglycemia and dyslipidemia in an animal model of type 2 diabetes. Fiveweek-old db/db mice were fed an AIN-93G diet or a diet containing 1% CM water extract, whereas db/+ mice were offered the AIN-93G diet for 6 weeks. Consumption of CM significantly decreased blood glycated hemoglobin and serum glucose levels, as well as homeostasis model assessment for insulin resistance (HOMA-IR), in db/db mice. CM significantly lowered serum triglyceride and total cholesterol levels, and increased HDL-cholesterol level. CM water extract inhibited rat intestinal α-glucosidase, with an IC50 of 182 μg/mL in vitro. These results indicate that CM exerted hypoglycemic and hypolipidemic effects in db/db mice.

Quercetin Ameliorates Insulin Sensitivity and Liver Steatosis Partly by Increasing Adiponectin Expression in ob/ob Mice

The effects of quercetin on non-alcoholic fatty liver disease (NAFLD) in an obese mouse model were investigated. Five-week-old ob/ob mice were fed an AIN-93G diet or a diet containing 0.08% quercetin, whereas ob/+ mice were provided the AIN-93G diet for 10 weeks. Quercetin significantly decreased serum glucose, triglycerides, cholesterol, and free fatty acid (FFA) levels, and homeostasis model assessment for insulin resistance (HOMA-IR) values, compared with the ob/ob control group. Quercetin lowered hepatic total lipids, triglycerides, and cholesterol levels, and the serum alanine transaminase (ALT) activities, compared with the ob/ob control group. Quercetin increased adiponectin protein expression in epididymal adipose tissue and serum adiponectin levels, and decreased serum tumor necrosis factor-α (TNF-α) and monocyte chemotactic protein-1 (MCP-1), compared with the ob/ob control group. These results indicate that quercetin could exert protective effects against development of NAFLD, partly by overexpression of adiponectin and reduction of inflammatory cytokine levels in ob/ob mice.