Screening of Potential α-Glucosidase Inhibitors from the Roots and Rhizomes of Panax Ginseng by Affinity Ultrafiltration Screening Coupled with UPLC-ESI-Orbitrap-MS Method

Panax ginseng was a traditional Chinese medicine with various pharmacological activities and one of its important activities was hypoglycemic activity; therefore, panax ginseng has been used in China as an adjuvant in the treatment of diabetes mellitus. In vivo and in vitro tests have revealed that ginsenosides, which are derived from the roots and rhizomes of panax ginseng have anti-diabetic effects and produce different hypoglycemic mechanisms by acting on some specific molecular targets, such as SGLT1, GLP-1, GLUTs, AMPK, and FOXO1. α-Glucosidase is another important hypoglycemic molecular target, and its inhibitors can inhibit the activity of α-Glucosidase so as to delay the absorption of dietary carbohydrates and finally reduce postprandial blood sugar. However, whether ginsenosides have the hypoglycemic mechanism of inhibiting α-Glucosidase activity, and which ginsenosides exactly attribute to the inhibitory effect as well as the inhibition degree are not clear, which needs to be addressed and systematically studied. To solve this problem, affinity ultrafiltration screening coupled with UPLC-ESI-Orbitrap-MS technology was used to systematically select α-Glucosidase inhibitors from panax ginseng. The ligands were selected through our established effective data process workflow based on systematically analyzing all compounds in the sample and control specimens. As a result, a total of 24 α-Glucosidase inhibitors were selected from panax ginseng, and it was the first time that ginsenosides were systematically studied for the inhibition of α-Glucosidase. Meanwhile, our study revealed that inhibiting α-Glucosidase activity probably was another important mechanism for ginsenosides treating diabetes mellitus. In addition, our established data process workflow can be used to select the active ligands from other natural products using affinity ultrafiltration screening.

Fructose Metabolism and Its Effect on Glucose-Galactose Malabsorption Patients: A Literature Review

Glucose-galactose malabsorption is a rare inherited autosomal recessive genetic defect. A mutation in the glucose sodium-dependent transporter-1 gene will alter the transportation and absorption of glucose and galactose in the intestine. The defect in the SGLT-1 leads to unabsorbed galactose, glucose, and sodium, which stay in the intestine, leading to dehydration and hyperosmotic diarrhea. Often, glucose-galactose malabsorption patients are highly dependent on fructose, their primary source of carbohydrates. This study aims to investigate all published studies on congenital glucose-galactose malabsorption and fructose malabsorption. One hundred published studies were assessed for eligibility in this study, and thirteen studies were identified and reviewed. Studies showed that high fructose consumption has many health effects and could generate life-threatening complications. None of the published studies included in this review discussed or specified the side effects of fructose consumption as a primary source of carbohydrates in congenital glucose-galactose malabsorption patients.

Control of cell metabolism by the epidermal growth factor receptor

The epidermal growth factor receptor (EGFR) triggers the activation of many intracellular signals that control cell proliferation, growth, survival, migration, and differentiation. Given its wide expression, EGFR has many functions in development and tissue homeostasis. Some of the cellular outcomes of EGFR signaling involve alterations of specific aspects of cellular metabolism, and alterations of cell metabolism are emerging as driving influences in many physiological and pathophysiological contexts. Here we review the mechanisms by which EGFR regulates cell metabolism, including by modulation of gene expression and protein function leading to control of glucose uptake, glycolysis, biosynthetic pathways branching from glucose metabolism, amino acid metabolism, lipogenesis, and mitochondrial function. We further examine how this regulation of cell metabolism by EGFR may contribute to cell proliferation and differentiation and how EGFR-driven control of metabolism can impact certain diseases and therapy outcomes.

Ginsenoside Rg1 interferes with the progression of diabetic osteoporosis by promoting type H angiogenesis modulating vasculogenic and osteogenic coupling

Ginsenoside Rg1 (Rg1) has been demonstrated to have antidiabetic and antiosteoporotic activities. The aim of this study was to investigate the protective effect of Rg1 against diabetic osteoporosis and the underlying mechanism. In vitro, we found that Rg1 increased the number of osteoprogenitors and alleviated high glucose (HG) induced apoptosis of osteoprogenitors by MTT assays and flow cytometry. qRT‒PCR and western blot analysis suggested that Rg1 can also promote the secretion of vascular endothelial growth factor (VEGF) by osteoprogenitors and promote the coupling of osteogenesis and angiogenesis. Rg1 can also promote the proliferation of human umbilical vein endothelial cells (HUVECs) cultured in high glucose, enhance the angiogenic ability of endothelial cells, and activate the Notch pathway to promote endothelial cells to secrete the osteogenesis-related factor Noggin to regulate osteogenesis, providing further feedback coupling of angiogenesis and osteogenesis. Therefore, we speculated that Rg1 may have similar effects on type H vessels. We used the Goto-Kakizaki (GK) rat model to perform immunofluorescence staining analysis on two markers of type H vessels, Endomucin (Emcn) and CD31, and the osteoblast-specific transcription factor Osterix, and found that Rg1 stimulates type H angiogenesis and bone formation. In vivo experiments also demonstrated that Rg1 promotes VEGF secretion, activates the Noggin/Notch pathway, increases the level of coupling between type H vessels and osteogenesis, and improves the bone structure of GK rats. All of these data reveal that Rg1 is a promising candidate drug for treating diabetic osteoporosis as a potentially bioactive molecule that promotes angiogenesis and osteointegration coupling.

The Lack of Bmal1, a Core Clock Gene, in the Intestine Decreases Glucose Absorption in Mice

The circadian clock network is an evolutionarily conserved system that regulates systemic metabolism, such as glucose homeostasis. Intestinal tissue is a pivotal organ for the regulation of glucose metabolism, mainly via glucose absorption into the circulation; however, the significance of the intestinal circadian clock network for glucose metabolism remains largely unclear. We herein utilized a mouse model in which Bmal1, a core clock gene, was deleted in an intestine-specific manner (Bmal1Int-/- mice) and demonstrated a rhythmic expression of Sglt1 with its peak at zeitgeber time (ZT) 10.7 ± 2.8 in control mice, whereas this was lost in Bmal1Int-/- mice. Mechanistically, chromatin immunoprecipitation analysis revealed rhythmic binding of CLOCK to the E-box elements in the Sglt1 gene in control mice; however, this was absent in Bmal1Int-/- mice. Accordingly, SGLT1 protein levels were decreased during the dark phase in Bmal1Int-/- mice and this was associated with impaired glucose absorption, leading to a decline in hepatic glycogen levels at ZT4, which was restored by ingestion of high-sucrose water. Additionally, when mice were starved from ZT0, greater expression of the lipolysis-related gene Pnpla2 was observed in adipose tissue of Bmal1Int-/- mice, and this was not noted when glycogen storage was restored by high-sucrose water prior to fasting, suggesting that higher Pnpla2 expression in Bmal1Int-/- mice was likely caused by lower glycogen storage. These results indicate that disruption of the intestinal circadian clock system impairs glucose absorption in the intestine and affects systemic glucose homeostasis.

Glycaemia and body weight are regulated by sodium-glucose cotransporter 1 (SGLT1) expression via O-GlcNAcylation in the intestine

Objective

Methods

Results

Conclusion

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Intestine-specific OGT depletion results in weight loss and hypoglycaemia.

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It reduces SGLT1 expression, resulting in glucose absorption from the gut.

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OGT knockdown may contribute to diminish glucose-induced incretin secretion.

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OGT may regulate SGLT1 expression via the cAMP/CREB-dependent pathway.

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O-GlcNAcylation regulates SGLT1 expression in the intestine and the kidney.

Ginsenoside Ro Ameliorates High-Fat Diet-Induced Obesity and Insulin Resistance in Mice via Activation of the G Protein-Coupled Bile Acid Receptor 5 Pathway

Obesity, a well known risk factor in multiple metabolic diseases, is dramatically increasing worldwide. Ginsenosides extracted from ginseng have been reported against obesity and the associated metabolic disorders. As a subtype of ginsenoside, ginsenoside Ro is a critical constituent of ginseng. However, its specific effects on obesity remain unknown. G protein-coupled bile acid receptor 5 (TGR5) (also known as GPBAR1) is a bile acid membrane receptor, widely expressed in human tissues contributing to various metabolic processes to confer the regulations of glucose and lipid homeostasis. TGR5 has displayed potential as a therapeutic target for the treatment of metabolic disorders. Here, we explore the antiobesity effect of ginsenoside Ro with TGR5 activation screened by a library of natural products. Our results showed that the ginsenoside Ro (90mg/kg) treatment ameliorated body weight and lipid accumulation in multiple metabolic organs of high-fat diet-induced obese (DIO) mice without affecting food intake and improved oral glucose tolerance tests, intraperitoneal insulin tolerance tests, and fasting serum glucose. We also found that triglyceride and total cholesterol in serum and liver were significantly decreased after ginsenoside Ro treatment. Then we used Tgr5 knockout mice to explore the role of Tgr5 in the antiobesity effect of ginsenoside Ro. Our results further demonstrated that ginsenoside Ro promoted glucagon-like peptide 1 (GLP-1) secretion and energy expenditure in wild-type DIO mice. However, the stimulation of ginsenoside Ro on GLP-1 secretion and energy expenditure were restrained in the Tgr5 knockout mice. In conclusion, our findings demonstrated that ginsenoside Ro ameliorates obesity and insulin resistance in DIO mice via activating TGR5, indicating a potential therapeutic role of ginsenoside Ro to treat obesity and its associated metabolic diseases. SIGNIFICANCE STATEMENT: Obesity is dramatically increasing worldwide, and it contributes to multiple metabolic diseases. G protein-coupled bile acid receptor 5 (TGR5) is a potential therapeutic target for the treatment of metabolic disorders. Ginsenoside Ro, as an oleanane-type ginsenoside, ameliorates obesity and insulin resistance, promotes glucagon-like peptide 1 secretion, and increases energy expenditure via activating TGR5. Ginsenoside Ro could be a potential leading compound for treating obesity and its associated metabolic diseases.

Glucose transporters in the small intestine in health and disease

Absorption of monosaccharides is mainly mediated by Na+-D-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of D-glucose and D-galactose while GLUT5 is relevant for D-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal D-glucose concentrations, respectively. At high luminal D-glucose, the abundance SGLT1 in the BBM is increased. Hence, D-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity D-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease D-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between D-fructose transport and metabolism, are discussed.

Ginsenoside Rg1 protects mice against streptozotocin-induced type 1 diabetic by modulating the NLRP3 and Keap1/Nrf2/HO-1 pathways

Ginseng has been traditionally used to treat diabetes mellitus (DM) in China. Ginsenoside Rg1 is a major active ingredient in processed ginseng, which elicits proven biological and pharmacological effects. Although a correlation between nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) and predisposition to type 1 diabetes mellitus (T1DM) has been identified, the mechanism underlying the potential function and activation of NLRP3 inflammasome in DM have not been elucidated to date. The present study aimed to elucidate the effects and underlying mechanism of Rg1 on streptozotocin (STZ)-induced T1DM in mice through short or long-term observation. Concurrently, we intended to explore the relationships between inflammasome, pyroptosis and oxidative stress and the role of NLRP3 and Keap1/Nrf2/HO-1 pathways in the development and progression of DM. Using ELISA and Western blot analysis, we found that Rg1 attenuated abnormally elevated blood glucose, reduced inflammatory factors IL-1β and IL-18 in the blood, decreased ALT and AST levels, promoted insulin secretion, and weakened the function of NLRP3 in mouse liver and pancreas. In addition, Rg1 protected against STZ-induced reactive oxygen species-mediated inflammation by upregulating Nrf2/ARE pathway, which further activated antioxidant enzymes. Interestingly, Rg1 also regulated H3K9 methylation in liver and pancreas, as detected by immunohistochemistry. In summary, these data provide new understanding about the mechanism of Rg1 action, suggesting that it is a potential drug applied for preventing the occurrence and development of T1DM.

Toxicological Evaluation of a Mixture of Astragalus membranaceus and Panax notoginseng Root Extracts (InnoSlim®)

Astragalus spp. and Panax spp. have a long history of traditional human use. A blend, InnoSlim®, of highly purified and fractionated root extracts from Astragalus membranaceus and Panax notoginseng has now been developed for human consumption; however, the unique constituent content of this blend has not been specifically evaluated with respect to safety. Therefore, the toxicological potential of the blend was formally investigated in a series of studies—genetic toxicity was evaluated in a bacterial reverse mutation test followed by an in vivo mammalian micronucleus test, and general toxicity was evaluated in a 28-day repeated-dose oral toxicity study in rats. No evidence of mutagenicity was observed in the bacterial tester strains used, and no evidence of in vivo chromosomal damage resulting in increased frequency of micronucleated cells was observed in male Crl:NMRI BR mice. No mortality or toxic effects were observed, and no target organs were identified, in male and female Han:WIST rats exposed to 0, 400, 800, or 1200 mg/kg bw/day of the blend by gavage for 28 consecutive days. The highest dose—1200 mg/kg bw/day—was determined to be the NOAEL. Based on these results, extrapolation towards a safe human consumption level can be explored.

SLC5A1 promotes growth and proliferation of pancreatic carcinoma via glucose-dependent AMPK/mTOR signaling

Background: Accumulating studies have reported that aberrant expression of SLC5A1 is a negative prognostic factor to various cancer patients.

Purpose: Pancreatic cancer tissue has also shown to harbor higher expression of SLC5A1, however how SLC5A1 mediates pancreatic cancer cells growth remains unclear.

Methods: In this study, we examined the mRNA and protein expressions of SLC5A1 in human pancreatic tissue and various cell lines. The in vitro and in vivo roles of SLC5A1 in pancreatic cancer were investigated through stably transfected pancreatic cells with shRNA plasmid targeting SLC5A1.

Results: Our results observed SLC5A1 was over-expressed in human pancreatic cancer tissues as well as most pancreatic cancer cell lines. Both in vitro and in vivo inhibition of SLC5A1 retarded pancreatic cancer cell growth and progression. The SLC5A1 knockdown mediated growth suppression is mainly regulated by reduced cellular glucose uptake by pancreatic cancer cells. Our further mechanistic observation showed that inhibition of SLC5A1 induced AMPK-dependent mTOR suppression and pharmacological inhibition of AMPK rescued the effect of SLC5A1 blockade. Further protein-protein interaction analysis showed association of SLC5A1 with EGFR and knockdown of EGFR also showed decreased cellular survival and glucose uptake by pancreatic cancer cells.

Conclusion: Our findings postulated SLC5A1/EGFR as the potential therapeutic target of pancreatic cancer patients.

Effects of Huanglian-Renshen-Decoction, a Fixed Mixture of Traditional Chinese Medicine, on the Improvement of Glucose Metabolism by Maintenance of Pancreatic β Cell Identity in db/db Mice

Huanglian-Renshen-Decoction (HRD) is widely used to treat type 2 diabetes mellitus (T2DM) in China. However, the underlying mechanism is unclear. We aimed to investigate the mechanism by which HRD regulates the glucose level. Forty 7-8-week-old db/db (BSK) mice were randomly assigned to the following four groups: model, low dose HRD (LHRD), high dose HRD (HHRD), and saxagliptin (SAX). Additionally, 10 db/m mice were assigned to control group. The experimental mice were administered 3.03g/kg/d and 6.06g/kg/d of HRD in the LHRD and HHRD groups, respectively, and 10mg/kg/d saxagliptin in the SAX group for 8 weeks. The control and model groups were supplied with distilled water. After the intervention, the pancreas and blood were collected and tested. Compared with that of model group, the fasting blood glucose (FBG) was significantly decreased in all intervention groups (p < 0.05 or 0.01), whereas fasting serum insulin (FINS) was increased significantly in both HHRD and SAX groups. The immunofluorescence images showed that the mass of insulin⁺ cells was increased and that of glucagon⁺ cells was reduced obviously in experimental groups compared to those of the model group. In addition, the coexpression of insulin, glucagon, and PDX1 was decreased in HHRD group, and the level of caspase 12 in islet was decreased significantly in all intervention groups. However, little difference was found in the number and morphology of islet, and the expression of ki67, bcl2, bax, caspase 3, and cleaved-caspase 3 in the pancreas among groups. Interestingly, the cleaved-Notch1 level was increased and the Ngn3 level in islet was decreased significantly in HHRD group. The HRD showed dose-dependent effects on glucose metabolism improvement through maintenance of β cell identity via a mechanism that might involve the Notch1/Ngn3 signal pathway in db/db mice.

Therapeutic Potential of Ginsenosides as an Adjuvant Treatment for Diabetes

Ginseng, one of the oldest traditional Chinese medicinal herbs, has been used widely in China and Asia for thousands of years. Ginsenosides extracted from ginseng, which is derived from the roots and rhizomes of Panax ginseng C. A. Meyer, have been used in China as an adjuvant in the treatment of diabetes mellitus. Owing to the technical complexity of ginsenoside production, the total ginsenosides are generally extracted. Accumulating evidence has shown that ginsenosides exert antidiabetic effects. In vivo and in vitro tests revealed the potential of ginsenoside Rg1, Rg3, Rg5, Rb1, Rb2, Rb3, compound K, Rk1, Re, ginseng total saponins, malonyl ginsenosides, Rd, Rh2, F2, protopanaxadiol (PPD) and protopanaxatriol (PPT)-type saponins to treat diabetes and its complications, including type 1 diabetes mellitus, type 2 diabetes mellitus, diabetic nephropathy, diabetic cognitive dysfunction, type 2 diabetes mellitus with fatty liver disease, diabetic cerebral infarction, diabetic cardiomyopathy, and diabetic erectile dysfunction. Many effects are attributed to ginsenosides, including gluconeogenesis reduction, improvement of insulin resistance, glucose transport, insulinotropic action, islet cell protection, hepatoprotective activity, anti-inflammatory effect, myocardial protection, lipid regulation, improvement of glucose tolerance, antioxidation, improvement of erectile dysfunction, regulation of gut flora metabolism, neuroprotection, anti-angiopathy, anti-neurotoxic effects, immunosuppression, and renoprotection effect. The molecular targets of these effects mainly contains GLUTs, SGLT1, GLP-1, FoxO1, TNF-α, IL-6, caspase-3, bcl-2, MDA, SOD, STAT5-PPAR gamma pathway, PI3K/Akt pathway, AMPK-JNK pathway, NF-κB pathway, and endoplasmic reticulum stress. Rg1, Rg3, Rb1, and compound K demonstrated the most promising therapeutic prospects as potential adjuvant medicines for the treatment of diabetes. This paper highlights the underlying pharmacological mechanisms of the anti-diabetic effects of ginsenosides.

Alcohol extract of North American ginseng (Panax quinquefolius) reduces fatty liver, dyslipidemia, and other complications of metabolic syndrome in a mouse model

We investigated whether North American ginseng (Panax quinquefolius) could reduce development of the metabolic syndrome phenotype in a mouse model (ETKO) of the disease. Young ETKO mice have no disease but similar to humans start to develop the fatty liver, hypertriglyceridemia, obesity, and insulin resistance at 25-30 weeks of age, and the disease continues to progress with ageing. ETKO mice were orally given an ethanol extract of ginseng roots at 4 and 32 weeks of age. Treatments with ginseng eliminated the ETKO fatty liver, reduced hepatic and intestinal lipoprotein secretion, and reduced the level of circulating lipids. Improvements by ginseng treatments were manifested as a reduction in the expression of genes involved in the regulation of fatty acid and triglyceride (fat) synthesis and secretion by the lipoproteins on one hand, and the stimulation of fatty acid oxidation and triglyceride degradation by lipolysis on the other hand. These processes altogether improved glucose, fatty acid, and triglyceride metabolism, reduced liver fat load, and reversed the progression of metabolic syndrome. These data confirm that treatments with North American ginseng could alleviate metabolic syndrome through the maintenance of a better balance between glucose and fatty acid metabolism, lipoprotein secretion, and energy homeostasis in disease-prone states.

Ginseng and obesity

Although ginseng has been shown to have an antiobesity effect, antiobesity-related mechanisms are complex and have not been completely elucidated. In the present study, we evaluated ginseng’s effects on food intake, the digestion, and absorption systems, as well as liver, adipose tissue, and skeletal muscle in order to identify the mechanisms involved. A review of previous in vitro and in vivo studies revealed that ginseng and ginsenosides can increase energy expenditure by stimulating the adenosine monophosphate-activated kinase pathway and can reduce energy intake. Moreover, in high fat diet-induced obese and diabetic individuals, ginseng has shown a two-way adjustment effect on adipogenesis. Nevertheless, most of the previous studies into antiobesity effects of ginseng have been animal based, and there is a paucity of evidence supporting the suggestion that ginseng can exert an antiobesity effect in humans.