Regulation of signaling molecules associated with insulin action, insulin secretion and pancreatic β-cell mass in the hypoglycemic effects of Korean red ginseng in Goto-Kakizaki rats

A comprehensive review on the phytochemistry, pharmacokinetics, and antidiabetic effect of Ginseng

BACKGROUND

Radix Ginseng, one of the well-known medicinal herbs, has been used in the management of diabetes and its complications for more than 1000 years.

PURPOSE

The aim of this review is devoted to summarize the phytochemistry and pharmacokinetics of Ginseng, and provide evidence for the antidiabetic effects of Ginseng and its ingredients as well as the underlying mechanisms involved.

METHODS

For the purpose of this review, the following databases were consulted: the PubMed Database (https://pubmed.ncbi.nlm.nih.gov), Chinese National Knowledge Infrastructure (http://www.cnki.net), National Science and Technology Library (http://www.nstl.gov.cn/), Wanfang Data (http://www.wanfangdata.com.cn/) and the Web of Science Database (http://apps.webofknowledge.com/).

RESULTS

Ginseng exhibits glucose-lowering effects in different diabetic animal models. In addition, Ginseng may prevent the development of diabetic complications, including liver, pancreas, adipose tissue, skeletal muscle, nephropathy, cardiomyopathy, retinopathy, atherosclerosis and others. The main ingredients of Ginseng include ginsenosides and polysaccharides. The underlying mechanisms whereby this herb exerts antidiabetic activities may be attributed to the regulation of multiple signaling pathways, including IRS1/PI3K/AKT, LKB1/AMPK/FoxO1, AGEs/RAGE, MAPK/ERK, NF-κB, PPARδ/STAT3, cAMP/PKA/CERB and HIF-1α/VEGF, etc. The pharmacokinetic profiles of ginsenosides provide valuable information on therapeutic efficacy of Ginseng in diabetes. Although Ginseng is well-tolerated, dietary consumption of this herb should follow the doctors' advice.

CONCLUSION

Ginseng may offer an alternative strategy in protection against diabetes and its complications through the regulations of the multi-targets via various signaling pathways. Efforts to understand the underlying mechanisms with strictly-controlled animal models, combined with well-designed clinical trials and pharmacokinetic evaluation, will be important subjects of the further investigations and weigh in translational value of this herb in diabetes management.

The effects of ginseng on the metabolic syndrome: An updated review

Metabolic syndrome is a group of risk factors including high blood glucose, dyslipidemia, high blood pressure, and high body weight. It can increase the risk of diabetes and cardiovascular disorders, which are the important reasons for death around the world. Nowadays, there are numerous demands for herbal medicine because of less harmful effects and more useful effects in comparison with chemical options. Ginseng is one of the most famous herbs used as a drug for a variety of disorders in humans. The antihyperlipidemia, antihypertension, antihyperglycemic, and anti-obesity effects of ginseng and its active constituents such as ginsenosides have been shown in different studies. In this review article, the different in vitro, in vivo, and human studies concerning the effects of ginseng and its active constituents in metabolic syndrome have been summarized. According to these studies, ginseng can control metabolic syndrome and related diseases.

Gut Microbiome Prolongs an Inhibitory Effect of Korean Red Ginseng on High-Fat-Diet-Induced Mouse Obesity

Although the anti-obesity effect of Korean red ginseng (Panax ginseng Meyer) has been revealed, its underlying mechanisms are not clearly understood. Here, we demonstrate an involvement of gut microbiome in the inhibitory effect of Korean red ginseng on high-fat-diet (HFD)-induced mouse obesity, and further provides information on the effects of saponin-containing red ginseng extract (SGE) and saponin-depleted red ginseng extract (GE). Mice were fed with either SGE or GE every third day for one month, and their food intakes, fat weights, plasma glucose, and insulin and leptin levels were measured. Immunofluorescence assays were conducted to measure pancreatic islet size. Stools from the mice were subjected to metagenomic analysis. Both SGE and GE attenuated HFD-induced gain of body weight, reducing HFD-induced increase of food intakes and fat weights. They also reduced HFD-increased plasma glucose, insulin, and leptin levels, decreased both fasting and postprandial glucose concentrations, and improved both insulin resistance and glucose intolerance. Immunofluorescence assays revealed that they blocked HFD-induced increase of pancreatic islet size. Our pyrosequencing of the 16S rRNA gene V3 region from stools revealed that both SGE and GE modulated HFD-altered composition of gut microbiota. Therefore, we conclude that Korean red ginseng inhibits HFD-induced obesity and diabetes by altering gut microbiome.

Resveratrol Affects Insulin Signaling in Type 2 Diabetic Goto-Kakizaki Rats

Resveratrol is a biologically active diphenolic compound exerting multiple beneficial effects in the organism, including anti-diabetic properties. This action is, however, not fully elucidated. In the present study, we examined effects of resveratrol on some parameters related to insulin signaling, and also on diabetes-associated dysregulation in Goto-Kakizaki (GK) rats with congenital type 2 diabetes. Resveratrol was given at the dose of 20 mg/kg b.w. for 10 weeks. It was shown that the expression and phosphorylation levels of insulin receptor in the skeletal muscle of GK rats were significantly decreased, compared with control animals. However, these changes were totally prevented by resveratrol. Liver expression of the insulin receptor was also reduced, but in this case, resveratrol was ineffective. Resveratrol was also demonstrated to significantly influence parameters of insulin binding (dissociation constant and binding capacity) in the skeletal muscle and liver. Moreover, it was shown that the expression levels of proteins related to intracellular glucose transport (GLUT4 and TUG) in adipose tissue of GK rats were significantly decreased. However, treatment with resveratrol completely abolished these changes. Resveratrol was found to induce normalization of TUG expression in the skeletal muscle. Blood levels of insulin and GIP were elevated, whereas proinsulin and GLP-1 diminished in GK rats. However, concentrations of these hormones were not affected by resveratrol. These results indicate that resveratrol partially ameliorates diabetes-associated dysregulation in GK rats. The most relevant finding covers the normalization of the insulin receptor expression in the skeletal muscle and also GLUT4 and TUG in adipose tissue.

Inhibition of Digestive Enzyme and Stimulation of Human Liver Cells (HepG2) Glucose Uptake by Date Seeds Extract

Type 2 diabetes mellitus is increasing worldwide, and the United Arab Emirates is presenting one of the world's highest prevalence rates. Dietary polyphenols exert an antidiabetic effect by modulating carbohydrates digestion and cellular glucose uptake. Due to their particularly high content in polyphenols, date seeds represent a potential antidiabetic agent. This study aims to determine if date seed polyphenols inhibit the activity of the enzymes (α-amylase and α-glucosidase), responsible for the digestion of carbohydrates and modulating the glucose uptake by human liver cells. In vitro activity of the intestinal α-glucosidase, pancreatic α-amylase, the glucose uptake by HepG2 cells, and the expression of GLUT4 and AMPK analyzed by western blotting (with and without date seeds extract). Our result showed that the maximum enzymes inhibition was obtained with 400 μg/mL and 900 μg/mL DSE for α-amylase and α-glucosidase, respectively. The HepG2 cell viability significantly decreased up to 80% at 4000 μg/mL DSE. The expression of GLUT4 was higher at 100 μg/mL DSE (with insulin and without insulin). However, the expressions of P-AMPK and AMPK were increased by DSE, mainly in a non-insulin-dependent manner. Therefore, DSE, by inhibiting carbohydrate digestion and stimulating glucose uptake by HepG2, can potentially demonstrate the therapeutic potential for diabetes management.

Korean red ginseng attenuates hyperglycemia-induced renal inflammation and fibrosis via accelerated autophagy and protects against diabetic kidney disease

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng C.A. Mey. (Korean ginseng) has been widely used in traditional medicine to treat diabetes mellitus for thousands of years. It also plays a key role in health maintenance owing to its anti-oxidant and anti-fatigue properties, and is quite popular as a dietary supplement.

AIM OF THE STUDY

This study was designed to offer a complementary and alternative medicine to manage the diabetic kidney disease (DKD), which causes long-term damage to the renal structure. We also investigated the regulation of the autophagy mechanism, which is the underlying the pathogenesis of DKD.

MATERIALS AND METHODS

The effect of Korean red ginseng (KRG) on DKD was evaluated using human kidney proximal tubular cells and streptozotocin (STZ)-treated Sprague-Dawley rat models. In vitro experiments were conducted to evaluate the proteins related to fibrosis and autophagy. This was followed by in vivo experiments involving rats treated with single intraperitoneal administration of STZ (60 mg/kg) and then with KRG solution orally for 4 weeks. Proteins related to renal injury, fibrosis, and autophagy were determined by immunoblotting. Hematoxylin and eosin (H&E), Periodic acid-Schiff (PAS), Sirius red, and immunostaining were processed for histological studies.

RESULTS

KRG diminished the levels of metabolic measurements and blood parameters. Western blotting showed a decreased expression of proteins, such as TGF-β1, KIM1, and AGE, which are responsible for renal inflammation, injury, and fibrosis. Histological studies also supported these results and revealed that the KRG-treated groups recovered from renal injury and fibrosis. Furthermore, the autophagy marker, LC3, was upregulated, whereas p62 was downregulated. The levels of proteins related to the autophagy mechanism, such as ATG7, increased, while mammalian target of rapamycin (mTOR) decreased with the KRG treatment and exhibited accelerated autophagy compared to the STZ alone group.

CONCLUSIONS

KRG can suppress renal inflammation, injury, and fibrosis by blocking TGF-β1 activation and can induce cellular autophagy. Therefore, this study strongly suggests that KRG exhibits a renoprotective effect against the STZ-induced DKD.

Antioxidant Effects and Mechanisms of Medicinal Plants and Their Bioactive Compounds for the Prevention and Treatment of Type 2 Diabetes: An Updated Review

Diabetes mellitus is a metabolic disorder that majorly affects the endocrine gland, and it is symbolized by hyperglycemia and glucose intolerance owing to deficient insulin secretory responses and beta cell dysfunction. This ailment affects as many as 451 million people worldwide, and it is also one of the leading causes of death. In spite of the immense advances made in the development of orthodox antidiabetic drugs, these drugs are often considered not successful for the management and treatment of T2DM due to the myriad side effects associated with them. Thus, the exploration of medicinal herbs and natural products as therapeutic sources for the treatment of T2DM is promoted because they have little or no side effects. Bioactive molecules isolated from natural sources have been proven to lower blood glucose levels via regulating one or more of the following mechanisms: improvement of beta cell function, insulin resistance, glucose (re)absorption, and glucagon-like peptide-1 homeostasis. In recent times, the mechanisms of action of different bioactive molecules with antidiabetic properties and phytochemistry are gaining a lot of attention in the area of drug discovery. This review article presents an update of the findings from clinical research into medicinal plant therapy for T2DM.

Review of Ginseng Anti-Diabetic Studies

Ginseng is one of the most valuable and commonly used Chinese medicines not only in ancient China but also worldwide. Ginsenosides, also known as saponins or triterpenoids, are thought to be responsible for the beneficial effects of ginseng. In this review, we summarize recent publications on anti-diabetic studies of ginseng extracts and ginsenosides in cells, animals, and humans. It seems that the anti-diabetic effect of ginseng is positive for type 2 diabetic patients but has no significant impact on prediabetes or healthy adults. Regulation of insulin secretion, glucose uptake, anti-oxidative stress, and anti-inflammatory pathways may be the mechanisms involved with ginseng's anti-diabetic effects. Taken together, this summary provides evidence for the anti-diabetes effects of ginseng extracts and ginsenosides as well as the underlying mechanisms of their impact on diabetes.

Combination of Aronia, Red Ginseng, Shiitake Mushroom and Nattokinase Potentiated Insulin Secretion and Reduced Insulin Resistance with Improving Gut Microbiome Dysbiosis in Insulin Deficient Type 2 Diabetic Rats

The combination of freeze-dried aronia, red ginseng, ultraviolet-irradiated shiitake mushroom and nattokinase (AGM; 3.4:4.1:2.4:0.1) was examined to evaluate its effects on insulin resistance, insulin secretion and the gut microbiome in a non-obese type 2 diabetic animal model. Pancreatectomized (Px) rats were provided high fat diets supplemented with either (1) 0.5 g AGM (AGM-L), (2) 1 g AGM (AGM-H), (3) 1 g dextrin (control), or (4) 1 g dextrin with 120 mg metformin (positive-control) per kg body weight for 12 weeks. AGM (1 g) contained 6.22 mg cyanidin-3-galactose, 2.5 mg ginsenoside Rg3 and 244 mg β-glucan. Px rats had decreased bone mineral density in the lumbar spine and femur and lean body mass in the hip and leg compared to the normal-control and AGM-L and AGM-H prevented the decrease. Visceral fat mass was lower in the control group than the normal-control group and its decrease was smaller with AGM-L and AGM-H. HOMA-IR was lower in descending order of the control, positive-control, AGM-L, AGM-H and normal-control groups. Glucose tolerance deteriorated in the control group and was improved by AGM-L and AGM-H more than in the positive-control group. Glucose tolerance is associated with insulin resistance and insulin secretion. Insulin tolerance indicated insulin resistance was highly impaired in diabetic rats, but it was improved in the ascending order of the positive-control, AGM-L and AGM-H. Insulin secretion capacity, measured by hyperglycemic clamp, was much lower in the control group than the normal-control group and it was improved in the ascending order of the positive-control, AGM-L and AGM-H. Diabetes modulated the composition of the gut microbiome and AGM prevented the modulation of gut microbiome. In conclusion, AGM improved glucose metabolism by potentiating insulin secretion and reducing insulin resistance in insulin deficient type 2 diabetic rats. The improvement of diabetic status alleviated body composition changes and prevented changes of gut microbiome composition.

Effects of Moringa oleifera Leaves Extract on High Glucose-Induced Metabolic Changes in HepG2 Cells

Mitochondrial dysfunction is a hallmark of diabetes, but the metabolic alterations during early stages of the disease remain unknown. The ability of liver cells to rearrange their metabolism plays an important role in compensating the energy shortage and may provide cell survival. Moringa oleifera leaves have been studied for its health properties against diabetes, insulin resistance, and non-alcoholic liver disease. We postulated that M. oleifera executes a protective function on mitochondrial functionality in HepG2 treated with high glucose. We evaluated the effect of high glucose treatment on the mitochondrial function of HepG2 cells using a Seahorse extracellular flux analyzer (Agilent, Santa Clara, CA, USA), blue native polyacrylamide gel electrophoresis (BN-PAGE), and western blot analysis. For assessment of mitochondrial abnormalities, we measured the activity of mitochondrial Complex I and IV as well as uncoupling protein 2, and sirtuin 3 protein contents. Our results demonstrate that, under conditions mimicking the hyperglycemia, Complex I activity, UCP2, Complex III and IV subunits content, supercomplex formation, and acetylation levels are modified with respect to the control condition. However, basal oxygen consumption rate was not affected and mitochondrial reactive oxygen species production remained unchanged in all groups. Treatment of HepG2 cells with M. oleifera extract significantly increased both protein content and mitochondrial complexes activities. Nonetheless, control cells’ respiratory control ratio (RCR) was 4.37 compared to high glucose treated cells’ RCR of 15.3, and glucose plus M. oleifera treated cells’ RCR of 5.2, this indicates high-quality mitochondria and efficient oxidative phosphorylation coupling. Additionally, the state app was not altered between different treatments, suggesting no alteration in respiratory fluxes. These findings enhance understanding of the actions of M. oleifera and suggest that the known antidiabetic property of this plant, at least in part, is mediated through modulating the mitochondrial respiratory chain.

Panax ginseng improves glucose metabolism in streptozotocin-induced diabetic rats through 5' adenosine monophosphate kinase up-regulation

5′ AMP-activated protein kinase (AMPK), insulin receptors and transporters are distorted in diabetes mellitus. In this study, the effect of Panax ginseng was assessed on glucose manipulating enzymes activities and gene expression of AMPK, IRA and GLUT2 in streptozotocin-induced diabetic male rats. Forty male albino rats were randomly divided to four groups 10 rats of each, group I, normal control group (received saline orally); group II, normal rats received 200 mg/kg of Panax ginseng orally; group III, Streptozotocin (STZ) –induced diabetic rats and group IV, STZ-induced diabetic rats received 200 mg/kg of Panax ginseng orally. The duration of experiment was 30 days. Results showed the ability of Panax ginseng to induce a significant decrease in the blood glucose and increase in the serum insulin levels, hepatic glucokinase (GK), and glycogen synthase (GS) activities with a modulation of lipid profile besides high expression levels of AMPK, insulin receptor A (IRA), glucose transporting protein-2 (GLUT-2) in liver of diabetic rats. In conclusion, the obtained results point to the ability of Panax ginseng to improve the glucose metabolism in diabetic models.

Korean Red Ginseng Protects Against Mitochondrial Damage and Intracellular Inflammation in an Animal Model of Type 2 Diabetes Mellitus

Korean red ginseng (KRG), a heat-processed Korean ginseng (Panax ginseng C.A. Meyer), has been used as a traditional medicine for its beneficial effects on hyperglycemia. This study aimed to investigate whether the antidiabetic action of KRG in an animal model of type 2 diabetes mellitus (DM) is partly mediated by prevention of mitochondrial dysfunction and intracellular inflammation. Four-week-old C57BL/KsJ db/db mice (a genetic animal model of obese type 2 DM) and C57BL/KsJ db/+ mice were divided into three groups: db/+ mice (normoglycemic control group, n = 8), db/db mice (untreated DM group, n = 8), and db/db mice with KRG administration (KRG-treated DM group, n = 8). After 12 weeks, metabolic parameters of fasting blood glucose concentrations, hemoglobin A_1c (HbA_1c) level, insulin level, lipid profile, and leukocyte count were determined using high-performance liquid chromatography. Mitochondrial DNA (mtDNA) copy number and inflammatory marker (interleukin-6, cyclooxygenase-2, and C-reactive protein) expression levels were measured in skeletal muscle tissue using quantitative real-time PCR analysis. After 12 weeks of KRG treatment at 100 mg/kg, the fasting glucose, HbA_1c, insulin, and low-density lipoprotein cholesterol concentrations were lower, whereas mtDNA copy numbers were higher in the KRG-treated DM group than in the untreated DM group. Compared with the untreated DM group, the messenger RNA expression levels of mitochondrial biogenesis-related transcription factors and inflammatory markers were lower in the KRG-treated DM group. In conclusion, KRG had a beneficial effect on the metabolic profile by preserving mitochondrial function and protecting against intracellular inflammation.

Fermented Red Ginseng Potentiates Improvement of Metabolic Dysfunction in Metabolic Syndrome Rat Models

Metabolic syndrome including obesity, dyslipidemia and hypertension is a cluster of risk factors of cardiovascular disease. Fermentation of medicinal herbs improves their pharmacological efficacy. Red ginseng (RG), a widely used traditional herbal medicine, was reported with anti-inflammatory and anti-oxidant activity. Aim in the present study was to investigate that the effects of fermented red ginseng (FRG) on a high-fructose (HF) diet induced metabolic disorders, and those effects were compared to RG and losartan. Animals were divided into four groups: a control group fed a regular diet and tap water, and fructose groups that were fed a 60% high-fructose (HF) diet with/without RG 250 mg/kg/day or FRG 250 mg/kg/day for eight weeks, respectively. Treatment with FRG significantly suppressed the increments of body weight, liver weight, epididymal fat weight and adipocyte size. Moreover, FRG significantly prevented the development of metabolic disturbances such as hyperlipidemia and hypertension. Staining with Oil-red-o demonstrated a marked increase of hepatic accumulation of triglycerides, and this increase was prevented by FRG. FRG ameliorated endothelial dysfunction by downregulation of endothelin-1 (ET-1) and adhesion molecules in the aorta. In addition, FRG induced markedly upregulation of Insulin receptor substrate 1 (IRS-1) and glucose transporter type 4 (Glut4) in the muscle. These results indicate that FRG ameliorates obesity, dyslipidemia, hypertension and fatty liver in HF diet rats. More favorable pharmacological effects on HF diet induced metabolic disorders were observed with FRG, compared to an equal dose of RG. These results showed that the pharmacological activity of RG was enhanced by fermentation. Taken together, fermentated red ginseng might be a beneficial therapeutic approach for metabolic syndrome.

Antihyperglycemic and antihyperlipidemic activities of protodioscin in a high-fat diet and streptozotocin-induced diabetic rats

Protodioscin attenuated hyperglycaemia and dyslipidemia in diabetic rats by improving the insulin sensitivity and increasing adiponectin concentrations.

Ancient records and modern research on the mechanisms of chinese herbal medicines in the treatment of diabetes mellitus

Over the past decades, Chinese herbal medicines (CHM) have been extensively and intensively studied through from both clinical and experimental perspectives and CHM have been proved to be effective in the treatment of diabetes mellitus (DM). This study, by searching ancient records and modern research papers, reviewed CHM in terms of their clinical application and principal mechanism in the treatment of DM. We summarized the use of CHM mentioned in 54 famous ancient materia medica monographs and searched papers on the hypoglycemic effect of several representative CHM. Main mechanisms and limitations of CHM and further research direction for DM were discussed. On the basis of the study, we were led to conclude that TCM, as a main form of complementary and alternative medicine (CAM), was well recorded in ancient literatures and has less adverse effects as shown by modern studies. The mechanisms of CHM treatment of DM are complex, multilink, and multitarget, so we should find main hypoglycemic mechanism through doing research on CHM monomer active constituents. Many CHM monomer constituents possess noteworthy hypoglycemic effects. Therefore, developing a novel natural product for DM and its complications is of much significance. It is strongly significant to pay close attention to CHM for treatment of DM and its complications.

Reducing drug-herb interaction risk with a computerized reminder system

Background

Traditional Chinese medicine (TCM) and Western medicine are both popular in Taiwan. Approximately 14.1% of Taiwanese residents use Western drugs and Chinese herbs concurrently; therefore, drug–herb interaction is critical to patient safety. This paper presents a new procedure for reducing the risk of drug interactions.

Methods

Hospital computer systems are modified to ensure that drug–herb interactions are automatically detected when a TCM practitioner is writing a prescription. A pop-up reminder appears, warning of interactions, and the practitioner may adjust doses, delete herbs, or leave the prescription unchanged. A pharmacist will receive interaction information through the system and provide health education to the patient.

Results

During the 2011–2013 study period, 256 patients received 891 herbal prescriptions with potential drug–herb interactions. Three of the 50 patients who concurrently used ginseng and antidiabetic drugs manifested hypoglycemia (fasting blood sugar level ≤70 mg/dL).

Conclusion

Drug–herb interactions can cause adverse reactions. A computerized reminder system can enable TCM practitioners to reduce the risk of drug–herb interactions. In addition, health education for patients is crucial in avoiding adverse reaction by the interactions.

Red ginseng extract blocks histamine-dependent itch by inhibition of H1R/TRPV1 pathway in sensory neurons

Background

Korean Red Ginseng—a steamed root of Panax ginseng Meyer—has long been used as a traditional medicine in Asian countries. Its antipruritic effect was recently found, but no molecular mechanisms were revealed. Thus, the current study focused on determining the underlying molecular mechanism of Korean Red Ginseng extract (RGE) against histamine-induced itch at the peripheral sensory neuronal level.

Methods

To examine the antipruritic effect of RGE, we performed in vivo scratching behavior test in mice, as well as in vitro calcium imaging and whole-cell patch clamp experiments to elucidate underlying molecular mechanisms.

Results

The results of our in vivo study confirmed that RGE indeed has an antipruritic effect on histamine-induced scratching in mice. In addition, RGE showed a significant inhibitory effect on histamine-induced responses in primary cultures of mouse dorsal root ganglia, suggesting that RGE has a direct inhibitory effect on sensory neuronal level. Results of further experiments showed that RGE inhibits histamine-induced responses on cells expressing both histamine receptor subtype 1 and TRPV1 ion channel, indicating that RGE blocks the histamine receptor type 1/TRPV1 pathway in sensory neurons, which is responsible for histamine-dependent itch sensation.

Conclusion

The current study found for the first time that RGE effectively blocks histamine-induced itch in peripheral sensory neurons. We believe that the current results will provide an insight on itch transmission and will be helpful in understanding how RGE exerts its antipruritic effects.

A review on the medicinal potential of Panax ginseng saponins in diabetes mellitus

This review article summarizes the anti-diabetic effects and mechanisms ofPanax ginsengsaponins and its active specific ginsenosides.

Interactions between herbs and antidiabetics: an overview of the mechanisms, evidence, importance, and management

Complementary and alternative therapies are quickly gaining importance because they are perceived to be free of side effects due to their natural origin. However, herbal remedies are complex mixtures of bioactive entities, which may interact with prescription drugs through pharmacokinetic or pharmacodynamic mechanisms and sometimes result in life-threatening consequences. In particular, diabetes patients are often treated with multiple medications due to different comorbidities, and such patients use antidiabetic medications for their entire lives; thus, it is important to make the public aware of herb interactions with antidiabetic drugs. In this paper, we summarize the reports available on the interaction of herbal remedies with oral hypoglycemic agents and describe mechanisms, preclinical or clinical evidence, importance, and management strategies.

Effects of Korean red ginseng supplementation on muscle glucose uptake in high-fat fed rats

It has been recognized that ginseng has anti-diabetic effects in skeletal muscle, but the mechanism has not been intensively investigated. The aim of this study was to investigate the effects of Korean red ginseng (Panax ginseng) supplementation on muscle glucose uptake in high-fat fed rats. Sixteen rats were randomly divided into two groups: a control group (CON, n = 8) and a Korean red ginseng group (KRG, n = 8). The KRG group ingested RG extract (1 g·kg(-1), 6 days/week) mixed in water for two weeks. After the two-week treatment, plasma lipid profiles, and glucose and insulin concentrations were measured. The triglyceride (TG) and glucose transporter 4 (GLUT-4) contents were measured in the skeletal muscle and liver. The rate of glucose transport was determined under a submaximal insulin concentration during muscle incubation. Plasma FFA concentrations were significantly decreased in KRG (P < 0.05). Liver and muscle triglyceride concentrations were also decreased in the KRG treatment group (P < 0.05) compared to the CON group. In addition, resting plasma insulin and glucose levels were significantly lower after Korean red ginseng treatment (P < 0.05). However, muscle glucose uptake was not affected by Korean red ginseng treatment, as evidenced by the rate of glucose transport in the epitorchealis muscle under submaximal insulin concentrations. These results suggest that while KRG supplementation could improve whole body insulin resistance and plasma lipid profiles, it is unlikely to have an effect on the insulin resistance of skeletal muscle, which is the major tissue responsible for plasma glucose handling.

Effects of korean red ginseng on hearing and blood glucose levels in steroid therapy for sudden sensorineural hearing loss

OBJECTIVES

Korean red ginseng (KRG) has hypoglycemic, antioxidant, antithrombotic, and other beneficial effects in human. The present study evaluate the therapeutic effects of KRG on hearing recovery and glucocorticoid-induced hyperglycemia in patients with idiopathic sudden sensorineural hearing loss (SSNHL) undergoing systemic steroid therapy.

METHODS

The patients were divided into 2 groups: the steroid, and the combination of steroid and red ginseng. Pure tone averages (PTA) were assessed at the first visit and 2-month follow-up. All patients underwent fasting blood glucose analyses just before and on the fifth day of treatment. Both groups were treated with a 10-day course of oral methylprednisolone at tapering doses starting from a daily dose of 48 mg. To the combination group, KRG extract was administered by mouth at a daily dose of 3 g for 20 days in addition to methylprednisolone. Hearing gain was calculated comparing the initial PTA and PTA at 2 months' follow-up. Treatment responses were classified according to Siegel's criteria.

RESULTS

Pretreatment conditions were similar between the steroid (n=37) and combination groups (n=36). At 2 months after the treatment, PTA improved significantly in both groups, but there was no significant difference in the mean hearing gain & recovery rate. The non-diabetic subjects in the steroid group (n=27) exhibited a 24% increase in the mean blood glucose level during the systemic steroid therapy, while those in the combination group (n=34) showed no changes.

CONCLUSION

Although the KRG did not provide greater therapeutic effects on hearing recovery, we suggest that red ginseng can be a useful adjuvant to the current steroid therapy to normalize glucocorticoid-induced hyperglycemia in non-diabetic patients during the treatment of SSNHL.

Postprandial glucose-lowering effects of fermented red ginseng in subjects with impaired fasting glucose or type 2 diabetes: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Red ginseng is prepared by steaming raw ginseng, a process believed to increase the pharmacological efficacy. Further bioconversion of red ginseng through fermentation is known to increase its intestinal absorption and bioactivity, and bioconversion diminishes the toxicity of red ginseng's metabolite. This study was conducted to investigate the effects of daily supplementation with fermented red ginseng (FRG) on glycemic status in subjects with impaired fasting glucose or type 2 diabetes.

METHODS

This study was a four-week long, randomized, double-blind, placebo-controlled trial. Forty-two subjects with impaired fasting glucose or type 2 diabetes were randomly allocated to two groups assigned to consume either the placebo or fermented red ginseng (FRG) three times per day for four weeks. Fasting and postprandial glucose profiles during meal tolerance tests were assessed before and after the intervention.

RESULTS

FRG supplementation led to a significant reduction in postprandial glucose levels and led to an increase in postprandial insulin levels compared to the placebo group. There was a consistently significant improvement in the glucose area under the curve (AUC) in the FRG group. However, fasting glucose, insulin, and lipid profiles were not different from the placebo group.

CONCLUSION

Daily supplementation with FRG lowered postprandial glucose levels in subjects with impaired fasting glucose or type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01826409.

MicroRNA-24/MODY gene regulatory pathway mediates pancreatic β-cell dysfunction

Overnutrition and genetics both contribute separately to pancreatic β-cell dysfunction, but how these factors interact is unclear. This study was aimed at determining whether microRNAs (miRNAs) provide a link between these factors. In this study, miRNA-24 (miR-24) was highly expressed in pancreatic β-cells and further upregulated in islets from genetic fatty (db/db) or mice fed a high-fat diet, and islets subject to oxidative stress. Overexpression of miR-24 inhibited insulin secretion and β-cell proliferation, potentially involving 351 downregulated genes. By using bioinformatic analysis combined with luciferase-based promoter activity assays and quantitative real-time PCR assays, we identified two maturity-onset diabetes of the young (MODY) genes as direct targets of miR-24. Silencing either of these MODY genes (Hnf1a and Neurod1) mimicked the cellular phenotype caused by miR-24 overexpression, whereas restoring their expression rescued β-cell function. Our findings functionally link the miR-24/MODY gene regulatory pathway to the onset of type 2 diabetes and create a novel network between nutrient overload and genetic diabetes via miR-24.

Herbal therapies for type 2 diabetes mellitus: chemistry, biology, and potential application of selected plants and compounds

Diabetes mellitus has been recognized since antiquity. It currently affects as many as 285 million people worldwide and results in heavy personal and national economic burdens. Considerable progress has been made in orthodox antidiabetic drugs. However, new remedies are still in great demand because of the limited efficacy and undesirable side effects of current orthodox drugs. Nature is an extraordinary source of antidiabetic medicines. To date, more than 1200 flowering plants have been claimed to have antidiabetic properties. Among them, one-third have been scientifically studied and documented in around 460 publications. In this review, we select and discuss blood glucose-lowering medicinal herbs that have the ability to modulate one or more of the pathways that regulate insulin resistance, β-cell function, GLP-1 homeostasis, and glucose (re)absorption. Emphasis is placed on phytochemistry, anti-diabetic bioactivities, and likely mechanism(s). Recent progress in the understanding of the biological actions, mechanisms, and therapeutic potential of compounds and extracts of plant origin in type 2 diabetes is summarized. This review provides a source of up-to-date information for further basic and clinical research into herbal therapy for type 2 diabetes. Emerging views on therapeutic strategies for type 2 diabetes are also discussed.

Herbal therapies for type 2 diabetes mellitus: chemistry, biology, and potential application of selected plants and compounds

Background:

Diabetes mellitus, becoming the third killer of mankind after cancer and cardiovascular diseases, is one of the most challenging diseases facing health care professionals today. That is why; there has been a growing interest in the therapeutic use of natural products for diabetes, especially those derived from plants.

Aim:

To evaluate the anti-diabetic activity together with the accompanying biological effects of the fractions and the new natural compounds of Hyphaene thebaica (HT) epicarp.

Materials and Methods:

500 g of coarsely powdered of (HT) fruits epicarp were extracted by acetone. The acetone crude extract was fractionated with methanol and ethyl acetate leaving a residual water-soluble fraction WF. The anti-diabetic effects of the WF and one of its compounds of the acetone extract of the (HT) epicarp were investigated in this study using 40 adult male rats.

Results:

Phytochemical investigation of active WF revealed the presence of ten different flavonoids, among which two new natural compounds luteolin 7-O-[6”-O-α-Lrhamnopyranosyl]-β-D-galactopyranoside 3 and chrysoeriol 7-O-β-D-galactopyranosyl(1→2)-α-L-arabinofuranoside 5 were isolated. Supplementation of the WF improved glucose and insulin tolerance and significantly lowered blood glycosylated hemoglobin levels. On the other hand, compound 5 significantly reduced AST and ALT levels of liver, respectively. Likewise, the kidney functions were improved for both WF and compound 5, whereby both urea and creatinine levels in serum were highly significant

Conclusion:

The results justify the use of WF and compound 5 of the (HT) epicarp as anti-diabetic agent, taking into consideration that the contents of WF were mainly flavonoids

The role of uncoupling proteins in diabetes mellitus

Uncoupling proteins (UCPs) are anion carriers expressed in the mitochondrial inner membrane that uncouple oxygen consumption by the respiratory chain from ATP synthesis. The physiological functions of UCPs have long been debated since the new UCPs (UCP2 to 5) were discovered, and the role of UCPs in the pathogeneses of diabetes mellitus is one of the hottest topics. UCPs are thought to be activated by superoxide and then decrease mitochondrial free radicals generation; this may provide a protective effect on diabetes mellitus that is under the oxidative stress conditions. UCP1 is considered to be a candidate gene for diabetes because of its role in thermogenesis and energy expenditure. UCP2 is expressed in several tissues and acts in the negative regulation of insulin secretion by β-cells and in fatty acid metabolism. UCP3 plays a role in fatty acid metabolism and energy homeostasis and modulates insulin sensitivity. Several gene polymorphisms of UCP1, UCP2, and UCP3 were reported to be associated with diabetes. The progress in the role of UCP1, UCP2, and UCP3 on diabetes mellitus is summarized in this review.