Ginsenoside Rg2 induces orphan nuclear receptor SHP gene expression and inactivates GSK3β via AMP-activated protein kinase to inhibit hepatic glucose production in HepG2 cells

A ginsenoside G-Rg3 PEGylated long-circulating liposome for hyperglycemia and insulin resistance therapy in streptozotocin-induced type 2 diabetes mice

Ginsenoside (GS), one of the main active components in ginseng, can enhance insulin sensitivity, improve the function of islet β cells, and reduce cell apoptosis in the treatment of diabetes. However, the drawbacks of high lipid solubility, poor water solubility, and low oral availability in Ginsenoside Rg3 (G-Rg3) seriously limit further application of GS. In this work, a G-Rg3 PEGylated long-circulating liposome (PEG-L-Rg3) is designed and developed to improve symptoms in type 2 diabetic mice. The as-prepared PEG-L-Rg3 with a spherical structure shows a particle size of ∼ 140.5 ± 1.4 nm, the zeta potential of -0.10 ± 0.05 mV, and a high encapsulation rate of 99.8 %. Notably, in vivo experimental results demonstrate that PEG-L-Rg3 exhibits efficient ability to improve body weight and food intake in streptozotocin-induced type 2 diabetic mice. Moreover, PEG-L-Rg3 also enhances fasting insulin (FINS) and insulin sensitivity index (ISI). In addition, the glucose tolerance of mice is significantly improved after the treatment of PEG-L-Rg3, indicating that PEG-L-Rg3 can be a potential drug for the treatment of type 2 diabetes, which provides a new way for the treatment of type 2 diabetes using ginsenosides.

Ginsenosides for the treatment of insulin resistance and diabetes: Therapeutic perspectives and mechanistic insights

Diabetes mellitus (DM) is a systemic disorder of energy metabolism characterized by a sustained elevation of blood glucose in conjunction with impaired insulin action in multiple peripheral tissues (i.e., insulin resistance). Although extensive research has been conducted to identify therapeutic targets for the treatment of DM, its global prevalence and associated mortailty rates are still increasing, possibly because of challenges related to long-term adherence, limited efficacy, and undesirable side effects of currently available medications, implying an urgent need to develop effective and safe pharmacotherapies for DM. Phytochemicals have recently drawn attention as novel pharmacotherapies for DM based on their clinical relevance, therapeutic efficacy, and safety. Ginsenosides, pharmacologically active ingredients primarily found in ginseng, have long been used as adjuvants to traditional medications in Asian countries and have been reported to exert promising therapeutic efficacy in various metabolic diseases, including hyperglycemia and diabetes. This review summarizes the current pharmacological effects of ginsenosides and their mechanistic insights for the treatment of insulin resistance and DM, providing comprehensive perspectives for the development of novel strategies to treat DM and related metabolic complications.

Licochalcone A alleviates abnormal glucolipid metabolism and restores energy homeostasis in diet-induced diabetic mice

Licochalcone A (LCA) is a bioactive chalcone compound identified in licorice. This study aimed to investigate the effects of LCA on glucolipid metabolism and energy homeostasis, as well as the underlying mechanisms. Blood glucose levels, oral glucose tolerance, serum parameters, and histopathology were examined in high-fat-high-glucose diet (HFD)-induced diabetic mice, with metformin as a positive control. Additionally, changes in key markers related to glucolipid metabolism and mitochondrial function were analyzed to comprehensively assess LCA's effects on metabolism. The results showed that LCA alleviated metabolic abnormalities in HFD-induced diabetic mice, which were manifested by suppression of lipogenesis, promotion of lipolysis, reduction of hepatic steatosis, increase in hepatic glycogenesis, and decrease in gluconeogenesis. In addition, LCA restored energy homeostasis by promoting mitochondrial biogenesis, enhancing mitophagy, and reducing adenosine triphosphate production. Mechanistically, the metabolic benefits of LCA were associated with the downregulation of mammalian target of rapamycin complex 1 and activation of adenosine monophosphate-activated protein kinase, the two central regulators of metabolism. This study demonstrates that LCA can alleviate abnormal glucolipid metabolism and restore energy balance in diet-induced diabetic mice, highlighting its therapeutical potential for the treatment of diabetes.

Ginsenoside Rg2 inhibits osteoclastogenesis by downregulating the NFATc1, c-Fos, and MAPK pathways

Ginsenosides, among the most active components of ginseng, exhibit several therapeutic effects against cancer, diabetes, and other metabolic diseases. However, the molecular mechanism underlying the anti-osteoporotic activity of ginsenoside Rg2, a major ginsenoside, has not been clearly elucidated. This study aimed to determine the effects of ginsenoside Rg2 on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation. Results indicate that ginsenoside Rg2 inhibits RANKLinduced osteoclast differentiation of bone marrow macrophages (BMMs) without cytotoxicity. Pretreatment with ginsenoside Rg2 significantly reduced the RANKL-induced gene expression of c-fos and nuclear factor of activated T-cells (Nfatc1), as well as osteoclast-specific markers tartrate-resistant acid phosphatase (TRAP, Acp5) and osteoclast-associated receptor (Oscar). Moreover, RANKL-induced phosphorylation of mitogen-activated protein kinases (MAPKs) was decreased by ginsenoside Rg2 in BMM. Therefore, we suggest that ginsenoside Rg2 suppresses RANKLinduced osteoclast differentiation through the regulation of MAPK signaling-mediated osteoclast markers and could be developed as a therapeutic drug for the prevention and treatment of osteoporosis. [BMB Reports 2023; 56(10): 551-556].

Ginsenoside Rg2 Promotes the Proliferation and Stemness Maintenance of Porcine Mesenchymal Stem Cells through Autophagy Induction

Mesenchymal stem cells (MSCs) can be used as a cell source for cultivated meat production due to their adipose differentiation potential, but MSCs lose their stemness and undergo replicative senescence during expansion in vitro. Autophagy is an important mechanism for senescent cells to remove toxic substances. However, the role of autophagy in the replicative senescence of MSCs is controversial. Here, we evaluated the changes in autophagy in porcine MSCs (pMSCs) during long-term culture in vitro and identified a natural phytochemical, ginsenoside Rg2, that could stimulate pMSC proliferation. First, some typical senescence characteristics were observed in aged pMSCs, including decreased EdU-positive cells, increased senescence-associated beta-galactosidase activity, declined stemness-associated marker OCT4 expression, and enhanced P53 expression. Importantly, autophagic flux was impaired in aged pMSCs, suggesting deficient substrate clearance in aged pMSCs. Rg2 was found to promote the proliferation of pMSCs using MTT assay and EdU staining. In addition, Rg2 inhibited D-galactose-induced senescence and oxidative stress in pMSCs. Rg2 increased autophagic activity via the AMPK signaling pathway. Furthermore, long-term culture with Rg2 promoted the proliferation, inhibited the replicative senescence, and maintained the stemness of pMSCs. These results provide a potential strategy for porcine MSC expansion in vitro.

Anticolon Cancer Effect of Korean Red Ginseng via Autophagy- and Apoptosis-Mediated Cell Death

Ginseng (Panax ginseng Meyer) has been used in East Asian traditional medicine for a long time. Korean red ginseng (KRG) is effective against several disorders, including cancer. The cytotoxic effects of KRG extract in terms of autophagy- and apoptosis-mediated cell death and its mechanisms were investigated using human colorectal cancer lines. KRG induced autophagy-mediated cell death with enhanced expression of Atg5, Beclin-1, and LC3, and formed characteristic vacuoles in HCT-116 and SNU-1033 cells. An autophagy inhibitor prevented cell death induced by KRG. KRG generated mitochondrial reactive oxygen species (ROS); antioxidant countered this effect and decreased autophagy. KRG caused apoptotic cell death by increasing apoptotic cells and sub-G₁ cells, and by activating caspases. A caspase inhibitor suppressed cell death induced by KRG. KRG increased phospho-Bcl-2 expression, but decreased Bcl-2 expression. Moreover, interaction of Bcl-2 with Beclin-1 was attenuated by KRG. Ginsenoside Rg2 was the most effective ginsenoside responsible for KRG-induced autophagy- and apoptosis-mediated cell death. KRG induced autophagy- and apoptosis-mediated cell death via mitochondrial ROS generation, and thus its administration may inhibit colon carcinogenesis.

HM-chromanone suppresses hepatic glucose production via activation of AMP-activated protein kinase in HepG2 cell

We investigated whether (E)-5-hydroxy-7-methoxy-3-(2-hydroxybenzyl)-4-chromanone (HM-chromanone) could suppress the transcription factors expression and enzymes involved in glucose production by activating AMPK in hepatocytes. HepG2 cells were treated with a medium containing HM-chromanone (5-100 μM), compound C (10 μM) and insulin (100 nM). Glucose production and glycogen synthesis assay were determined using a glucose assay kit and glycogen assay kit, respectively. Activities of AMP-activated protein kinase (AMPK), acetyl CoA carboxylase (ACC), cAMP response element-binding protein (CREB), PPAR coactivator-1α (PGC1α), CREB-regulated transcription coactivator 2 (CRTC2), Glycogen synthase kinase (GSK3β), Phosphoenolpyruvate carboxykinase (PEPCK), glycogen synthase (GS), Glucose 6-phosphatase (G6pase) and β-actin were determined by Western blot analysis. HM-chromanone significantly inhibited hepatic glucose production and increased glycogen synthesis by activating glycogen synthase. HM-chromanone induced the phosphorylation of CRTC2 and GSK-3β by phosphorylating AMPK in HepG2 cells, which was confirmed by compound C. Furthermore, it significantly decreased the phosphorylation of CREB in a time- and concentration-dependent manner, and the effect was reversed in the presence of compound C. Therefore, the complex formation of CRTC2 and CREB was inhibited. HM-chromanone inhibited the expression of PGC-1α, PEPCK, and G6Pase genes involved in production of hepatic glucose. The results showed that HM-chromanone activates AMPK in a time and concentration dependent manner, thus suppressing hepatic glucose production and increasing glycogen synthesis in HepG2 cells.

Anti-adipogenic effect of the flavonoids through the activation of AMPK in palmitate (PA)-treated HepG2 cells

BACKGROUND

Flavonoids are natural polyphenols found widely in citrus fruit and peel that possess anti-adipogenic effects. On the other hand, the detailed mechanisms for the anti-adipogenic effects of flavonoids are unclear.

OBJECTIVES

The present study observed the anti-adipogenic effects of five major citrus flavonoids, including hesperidin (HES), narirutin (NAR), nobiletin (NOB), sinensetin (SIN), and tangeretin (TAN), on AMP-activated protein kinase (AMPK) activation in palmitate (PA)-treated HepG2 cells.

METHODS

The intracellular lipid accumulation and triglyceride (TG) contents were quantified by Oil-red O staining and TG assay, respectively. The glucose uptake was assessed using 2-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose (2-NBDG) assay. The levels of AMPK, acetyl-CoA carboxylase (ACC), and glycogen synthase kinase 3 beta (GSK3β) phosphorylation, and levels of sterol regulatory element-binding protein 2 (SREBP-2) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) expression were analyzed by Western blot analysis. The potential interaction between the flavonoids and the γ-subunit of AMPK was investigated by molecular docking analysis.

RESULTS

The flavonoid treatment reduced both intracellular lipid accumulation and TG content in PA-treated HepG2 cells significantly. In addition, the flavonoids showed increased 2-NBDG uptake in an insulin-independent manner in PA-treated HepG2 cells. The flavonoids increased the AMPK, ACC, and GSK3β phosphorylation levels and decreased the SREBP-2 and HMGCR expression levels in PA-treated HepG2 cells. Molecular docking analysis showed that the flavonoids bind to the CBS domains in the regulatory γ-subunit of AMPK with high binding affinities and could serve as potential AMPK activators.

CONCLUSION

The overall results suggest that the anti-adipogenic effect of flavonoids on PA-treated HepG2 cells results from the activation of AMPK by flavonoids.

The effects of naringenin and naringin on the glucose uptake and AMPK phosphorylation in high glucose treated HepG2 cells

Background

Naringin and its aglycone naringenin are citrus-derived flavonoids with several pharmacological effects. On the other hand, the mechanism for the anti-diabetic effects of naringenin and naringin are controversial and remain to be clarified further.

Objective

This study examined the relationship between glucose uptake and AMP-activated protein kinase (AMPK) phosphorylation by naringenin and naringin in high glucose-treated HepG2 cells.

Methods

Glucose uptake was measured using the 2-NBDG fluorescent D-glucose analog. The phosphorylation levels of AMPK and GSK3β (Glycogen synthase kinase 3 beta) were observed by Western blotting. Molecular docking analysis was performed to evaluate the binding affinity of naringenin and naringin to the γ-subunit of AMPK.

Results

The treatment with naringenin and naringin stimulated glucose uptake regardless of insulin stimulation in high glucose-treated HepG2 cells. Both flavonoids increased glucose uptake by promoting the phosphorylation of AMPK at Thr172 and increased the phosphorylation of GSK3β. Molecular docking analysis showed that both naringenin and naringin bind to the γ-subunit of AMPK with high binding affinities. In particular, naringin showed higher binding affinity than the true modulator, AMP with all three CBS domains (CBS1, 3, and 4) in the γ-subunit of AMPK. Therefore, both naringenin and naringin could be positive modulators of AMPK activation, which enhance glucose uptake regardless of insulin stimulation in high glucose-treated HepG2 cells.

Conclusions

The increased phosphorylation of AMPK at Thr172 by naringenin and naringin might enhance glucose uptake regardless of insulin stimulation in high glucose treated HepG2 cells.

Genus Pseudonocardia: What we know about its biological properties, abilities and current application in biotechnology

The genus Pseudonocardia belongs to a group of Actinomycetes, and is a member of the family Pseudonocardiacea. The members of this genus are aerobic, Gram-positive, non-motile bacteria that are commonly found in soil, plant and environment. Although this genus has a low clinical significance; however, it has an important role in biotechnology due to the production of secondary metabolites, some of which have anti-bacterial, anti-fungal and anti-tumour effects. The use of phenotypic tests, such as gelatinase activity, starch hydrolysis, catalase and oxidase tests, as well as molecular methods, such as polymerase chain reaction, are necessary for Pseudonocardia identification at the genus and species levels.

Protective effects of ginsenoside Rg2 against memory impairment and neuronal death induced by Aβ25-35 in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ginsenoside Rg2 is an important ingredient of Panax ginseng which often appears in ancient prescriptions for forgetfulness. Ginsenoside Rg2 exert neuroprotective effects and could be a new potential medicine to treat AD. In our previous study, we reported that ginsenoside Rg2 appears protect PC12 cells against Amyloid β-fragment (25-35) (Aβ_25-35)-induced apoptosis via the PI3K/Akt pathway. However, there are no in vivo studies on the protective effects of ginsenoside Rg2 on Aβ-induced neurotoxicity.

AIM OF THE STUDY

The present study was performed to investigate the protective effects of ginsenoside Rg2 against Aβ_25-35-induced memory impairment, and its underlying mechanisms in rats.

MATERIALS AND METHODS

An Alzheimer's Disease (AD) rat model was established by injecting the rats with Aβ_25-35 (1 μg/μl). Cognitive performance was evaluated by the Morris Water Maze test (MWM). The brain sections were processed and neuronal apoptosis in the hippocampus was evaluated by Hematoxylin and Eosin staining (H&E). To explore the anti-neuronal apoptosis mechanism of ginsenoside Rg2, we analyzed the protein expression of Bcl-2/Bax, caspase-3, and phospho-protein kinase B/protein kinase B (p-Akt/Akt) via western blot.

RESULTS

A significant improvement in cognitive function was observed in administrated ginsenoside Rg2 AD rats. The histological injury in hippocampus CA1 induced by Aβ_25-35 was inhibited following administration of the ginsenoside Rg2. Ginsenoside Rg2 increase the Bcl-2/Bax ratio, attenuate the cleavage of caspase-3, and enhance the phosphorylation of Akt.

CONCLUSIONS

These findings suggest that ginsenoside Rg2 could ameliorate Aβ_25-35-induced cognitive dysfunction by activating the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway.

Protective effects of ginsenoside-Rg2 and -Rh1 on liver function through inhibiting TAK1 and STAT3-mediated inflammatory activity and Nrf2/ARE-mediated antioxidant signaling pathway

Systemic or hepatic inflammation is caused by intraperitoneal application of lipopolysaccharide (LPS). In this study, we investigated anti-inflammatory and antioxidant properties of combination of ginsenoside-Rg2 (G-Rg2) and -Rh1 (G-Rh1) on liver function under LPS challenging. We first confirmed that G-Rg2 and -Rh1 at 100 μg/ml did not show cytotoxicity in HepG2 cells. G-Rg2 and -Rh1 treatment significantly inhibited activation of STAT3 and TAK1, and inflammatory factors including iNOS, TNF-α, and IL-1β in peritoneal macrophages. In HepG2 cells, G-Rg2 and -Rh1 treatment inhibited activation of STAT3 and TAK1/c-Jun N-terminal kinase, and down-regulated nuclear translocation of NF-κB transcription factor. In addition, LPS-induced mitochondrial dysfunction was restored by treatment with G-Rg2 and -Rh1. Interestingly, pretreatment with G-Rg2 and -Rh1 effectively inhibited mitochondrial damage-mediated ROS production induced by LPS stimulation, and alterations of Nrf2 nuclear translocation and ARE promotor activity were involved in G-Rg2 and -Rh1 effects on balancing ROS levels. In liver tissues of LPS-treated mice, G-Rg2 and -Rh1 treatment protected liver damages and increased Nrf2 expression while reducing CD45 expression. Taken together, G-Rg2 and -Rh1 exerts a protective effect on liver function by increasing antioxidant through Nrf2 and anti-inflammatory activities through STAT3/TAK1 and NF-κB signaling pathways in liver cells and macrophages.

Effect of Korean Red Ginseng on metabolic syndrome

Metabolic syndrome (MS) refers to a clustering of at least three of the following medical conditions: high blood pressure, abdominal obesity, hyperglycemia, low high-density lipoprotein level, and high serum triglycerides. MS is related to a wide range of diseases which includes obesity, diabetes, insulin resistance, cardiovascular disease, dyslipidemia, or non-alcoholic fatty liver disease. There remains an ongoing need for improved treatment strategies for MS. The most important risk factors are dietary pattern, genetics, old age, lack of exercise, disrupted biology, medication usage, and excessive alcohol consumption, but pathophysiology of MS has not been completely identified. Korean Red Ginseng (KRG) refers to steamed/dried ginseng, traditionally associated with beneficial effects such as anti-inflammation, anti-fatigue, anti-obesity, anti-oxidant, and anti-cancer effects. KRG has been often used in traditional medicine to treat multiple metabolic conditions. This paper summarizes the effects of KRG in MS and related diseases such as obesity, cardiovascular disease, insulin resistance, diabetes, dyslipidemia, or non-alcoholic fatty liver disease based on experimental research and clinical studies.

Minor Ginsenoside Rg2 and Rh1 Attenuates LPS-Induced Acute Liver and Kidney Damages via Downregulating Activation of TLR4-STAT1 and Inflammatory Cytokine Production in Macrophages

Ginsenosides have been reported to have various biological effects, such as immune regulation and anticancer activity. In this study, we investigated the anti-inflammatory role of a combination of Rg2 and Rh1, which are minor ginsenosides, in lipopolysaccharide (LPS)-stimulated inflammation. In vitro experiments were performed using the RAW264.7 cell line, and an in vivo model of inflammation was established using LPS-treated ICR mice. We employed Griess assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, quantitative reverse transcriptase-polymerase chain reaction, western blotting, immunofluorescence staining, and hematoxylin and eosin staining to evaluate the effect of Rg2 and Rh1. We found that Rg2 and Rh1 significantly decreased LPS-induced major inflammatory mediator production, inducible-nitric oxide synthase expression, and nitric oxide production in macrophages. Moreover, Rg2 and Rh1 combination treatment inhibited the binding of LPS to toll-like receptor 4 (TLR4) on peritoneal macrophages. Therefore, the combination of ginsenoside Rg2 and Rh1 suppressed inflammation by abolishing the binding of LPS to TLR4, thereby inhibiting the TLR4-mediated signaling pathway. The combined ginsenoside synergistically blocked LPS-mediated PKCδ translocation to the plasma membrane, resulting in p38-STAT1 activation and NF-κB translocation. In addition, mRNA levels of pro-inflammatory cytokines, including TNF-α, IL-1β, and IFN-β, were significantly decreased by combined ginsenoside treatment. Notably, the 20 mg/kg ginsenoside treatment significantly reduced LPS-induced acute tissue inflammation levels in vivo, as indicated by the tissue histological damage scores and the levels of biochemical markers for liver and kidney function from mouse serum. These results suggest that the minor ginsenosides Rg2 and Rh1 may play a key role in prevention of LPS-induced acute inflammation and tissue damage.

Ginsenoside Rg2 Ameliorates High-Fat Diet-Induced Metabolic Disease through SIRT1

Ginsenoside Rg2 has been previously reported to reduce glucose production and adipogenesis in adipose tissue. However, the effects of ginsenosides Rg2 on hepatic lipid metabolism remain vacant. In this study, we found that ginsenoside Rg2 treatment significantly attenuated oleic acid and palmitic acid (OA&PA)-induced intracellular lipid deposition and oxidative stress in mouse primary hepatocytes. C57BL/6J mice that are fed with a high-fat diet (HFD) and treated with ginsenosides Rg2 displayed decreased body weight, reversed hepatic steatosis, and improved glucose tolerance and insulin sensitivity. Ginsenoside Rg2 administration significantly ameliorated HFD-induced hepatic oxidative stress and apoptosis. Moreover, Ginsenoside Rg2 had a good affinity with Sirtuin1 (SIRT1) and regulated its expression in vivo and in vitro. Deficiency of SIRT1 eliminated the therapeutic effect of ginsenoside Rg2 on lipid accumulation and overproduction of reactive oxygen species (ROS) in OA&PA-induced mice primary hepatocytes. Ginsenoside Rg2 treatment failed to alter the lipid and glucose disorder in hepatic SIRT1 deficient mice feeding on HFD. SIRT1 deficiency dissolves the therapeutic effect of ginsenoside Rg2 on oxidative stress and hepatocyte apoptosis induced by HFD. In summary, ginsenoside Rg2 plays a therapeutic role in HFD-induced hepatosteatosis of mice by decreasing the lipogenesis process and improving antioxidant capacity in an SIRT1-dependent manner.

Ginsenoside Rk3 ameliorates high-fat-diet/streptozocin induced type 2 diabetes mellitus in mice via the AMPK/Akt signaling pathway

Ginsenoside Rk3 (G-Rk3) is a main active ingredient of ginsenosides. Several recent studies demonstrated that ginsenosides have potential anti-type 2 diabetes mellitus (T2DM) properties. To evaluate the anti-T2DM effect of G-Rk3 and verify its potential mechanism, a high-fat-diet/streptozocin (HFD/STZ) induced model of T2DM in C57BL/6 mice and a high glucose induced insulin resistance model of HepG2 cells were applied in this research. Our analysis indicated that G-Rk3 reduced HFD/STZ induced hyperglycemia, and serum insulin and inflammation levels, and ameliorated glucose tolerance and insulin resistance, and prevented liver histological changes. Furthermore, it also significantly reduced lipid accumulation as shown by lower TG, LDL-C and TC serum concentrations and Oil Red O staining in liver tissues. The hypoglycemic effect of G-Rk3 seemed to be partially mediated via the inhibition of hepatic gluconeogenesis, which was supported by the activated p-Akt, p-FoxO1 and GLUT2 and inhibited FoxO1, PEPCK and G6pase protein expressions in the liver as well as increased glucose uptake in high glucose induced HepG2 cells. The gene expressions of hepatic gluconeogenesis were also down-regulated by G-Rk3 in HFD/STZ induced T2DM mice. In addition, G-Rk3 suppressed HFD/STZ induced lipid accumulation by regulating related gene and protein expressions such as p-ACC, FAS and SREBP-1, which are the downstream targets of AMPK. AMPK and Akt inhibitors significantly reversed G-Rk3 mediated hepatic gluconeogenesis and lipid accumulation. Thus, our study is the first to illustrate that G-Rk3 mediates hepatic gluconeogenesis and lipid accumulation via activating the AMPK/Akt signaling pathway in HFD/STZ induced T2DM mice.

Anti-diabetic properties of different fractions of Korean red ginseng

ETHNOPHARMACOLOGICAL RELEVANCE

Korean red ginseng (KRG) has been traditionally used to treat diabetes. Ginsenosides are considered as the major bioactive components mediating anti-diabetic effects of KRG. However, considering that ginsenosides account for only about 3-4% of ginsengs, other fractions of KRG may also carry potential anti-diabetic effects. There is no study reporting the differentiated effects of ginsenosides (Spn) and non-saponin fractions (NSpn) of KRG on glycemic control.

AIM OF THE STUDY

We investigated the effects of KRG, Spn, and NSpn on the indications of glycemic control and sought to elucidate physiological factors contributing their effects.

MATERIALS AND METHODS

Human T2DM mimicking Nagoya-Shibata-Yasuda (NSY/hos) mice were given KRG, Spn, or NSpn admixed in rodent diet at 200 mg/kg/day for 24 weeks. Glycemic and obesity indications, blood lipid profile, systematic and local oxidative stress markers in metabolically important organs, and systematic inflammatory markers were assessed. Molecular assessments associated with glycemic control in liver and skeletal muscle were further performed.

RESULTS

KRG attenuated deterioration in glucose homeostasis as evidenced by significantly lower fasting blood glucose from 22^nd week and AUC during GTT at the end of the experiment compare to control. Spn enhanced insulin secretion in response to glucose stimulation and reduced protein level of glycogen phosphorylase in liver. On the other hand, NSpn ameliorated oxidative stress and inflammation. Some beneficial effects of Spn and NSpn were reflected in KRG treated mice. KRG also attenuated the accumulation of malondialdehyde in skeletal muscle and, accordingly, enhanced insulin responsiveness compare to control.

CONCLUSION

Anti-diabetic properties of KRG are not solely determined by the contents of ginsenosides but the harmonic functions of its different fractions.

Ginsenoside Rg2 inhibits adipogenesis in 3T3-L1 preadipocytes and suppresses obesity in high-fat-diet-induced obese mice through the AMPK pathway

Rg2-induced activation of AMPK reduced the expression of adipogenic transcription factors, and regulated the lipogenic and lipolysis genes, thus inhibiting adipogenesis.

Upregulation of autophagy by Ginsenoside Rg2 in MCF-7 cells

Autophagy is a major intracellular degradation process that plays an important role in cell survival, stress responses, nutrient sensing and development. Our previous studies have shown that Rg2, a triterpenoid saponin contained in ginseng, protects cells against UVB-induced genotoxicity by increasing DNA repair, in possible association with modulation of protein levels involved in p53 pathway. In this study, we determined an upregulation of autophagy by Rg2. Rg2 treatment for 24 h in MCF-7, a breast cancer cell, did not show cytotoxicity up to 200 μM. Rg2 also upregulated the level of p-p53, p-AMPK, p-ACC, Atg-7 and LC3-II and decreased the level of p62 in concentration-dependent manners. We also determined the level of p53, AMPK, p62, Atg-7 and LC3 after UVB exposure and subsequent incubation in growth medium for 24 h. UVB increased the level of p-p53, p-AMPK, p-ACC and decreased the levels of p62, Atg-7 and LC3-II. Interestingly, Rg2 treatment for 24 h after UVB exposure increased the levels of p-p53, p-AMPK, p-ACC, Atg-7 and LC3-II and decreased the level of cyclobutane pyrimidine dimer, a UVB-induced DNA damage in concentration-dependent manners. All these results suggest that Rg2 increased autophagy and decreased UVB-induced DNA damage, in possible association with the modulation of protein levels in p53- and autophagic pathways.

Ginsenosides: the need to move forward from bench to clinical trials

Panax ginseng, known as Koran ginseng, one of the most commonly used traditional plants, has been demonstrated to show a wide range of pharmacological applications. Ginsenosides are the major active ingredients found in ginseng and are responsible for the biological and pharmacological activities, such as antioxidation, antiinflammation, vasorelaxation, and anticancer actions. Existing studies have mostly focused on identifying and purifying single ginsenosides and investigating pharmacological activities and molecular mechanisms in cells and animal models. However, ginsenoside studies based on clinical trials have been very limited. Therefore, this review aimed to discuss the currently available clinical trials on ginsenosides and provide insights and future directions for developing ginsenosides as efficacious and safe drugs for human disease.

Transcriptome Profiling Analysis Reveals the Potential Mechanisms of Three Bioactive Ingredients of Fufang E'jiao Jiang During Chemotherapy-Induced Myelosuppression in Mice

Although multiple bioactive components have been identified in Fufang E’jiao Jiang (FEJ), their hematopoietic effects and molecular mode of action in vivo are still not fully understood. In the current study, we analyzed the effects of martynoside, R-notoginsenoside R2 (R2), and 20S-ginsenoside Rg2 (Rg2) in a 5-fluorouracil-induced myelosuppression mouse model. Bone marrow nucleated cells (BMNCs) counts, hematopoietic progenitor cell colony-forming unit (CFU) assay, as well as flow cytometry analysis of Lin^-/c-kit⁺/Sca-1⁺ hematopoietic stem cell (HSC) population were conducted, and bone marrow cells were subjected to RNA sequencing. The transcriptome data were processed based on the differentially expressed genes. The results of the analysis show that each of the three compounds stimulates BMNCs and HSC growth, as well as burst-forming unit-erythroid and colony-forming unit granulocyte-monocyte colony expansion. The most relevant transcriptional changes appeared to be involved in regulation of hematopoietic cell lineage, NF-κB and TNF-α signaling, inhibition of inflammation, and acceleration of hematopoietic cell recovery. Notably, the individual compounds shared similar but specified transcriptome profiles. Taken together, the hematopoietic effects for the three tested compounds of FEJ are confirmed in this myelosuppression mouse model. The transcriptome maps of these effects provide valuable information concerning their underlying mechanisms and provide a framework for the continued study of the complex mode of action of FEJ.

C-Phycocyanin inhibits hepatic gluconeogenesis and increases glycogen synthesis via activating Akt and AMPK in insulin resistance hepatocytes

The mechanism of C-PC in improving glucose homoeostasis is to activate the IRS/PI3 K/Akt and SIRT1/LKB1/AMPK signaling pathway in insulin resistant hepatocytes.

Panax ginseng and Panax quinquefolius: From pharmacology to toxicology

The use of Panax ginseng and Panax quinquefolius in traditional Chinese medicine dates back to about 5000 years ago thanks to its several beneficial and healing properties. Over the past few years, extensive preclinical and clinical evidence in the scientific literature worldwide has supported the beneficial effects of P. ginseng and P. quinquefolius in significant central nervous system, metabolic, infectious and neoplastic diseases. There has been growing research on ginseng because of its favorable pharmacokinetics, including the intestinal biotransformation which is responsible for the processing of ginsenosides - contained in the roots or extracts of ginseng - into metabolites with high pharmacological activity and how such principles act on numerous cell targets. The aim of this review is to provide a simple and extensive overview of the pharmacokinetics and pharmacodynamics of P. ginseng and P. quinquefolius, focusing on the clinical evidence which has shown particular effectiveness in specific diseases, such as dementia, diabetes mellitus, respiratory infections, and cancer. Furthermore, the review will also provide data on toxicological factors to support the favorable safety profile of these medicinal plants.

Ginsenoside Rg5 attenuates hepatic glucagon response via suppression of succinate-associated HIF-1α induction in HFD-fed mice

AIMS/HYPOTHESIS

Ginsenosides regulate glucose homeostasis. This study investigated the effect of ginsenoside Rg5 (Rg5) on the hepatic glucagon response, focusing on the regulation of metabolism.

METHODS

Mice fed a high-fat diet (HFD) showed increased hepatic glucose production (HGP). We observed the effects of Rg5 on hepatic fatty acid oxidation and glucagon response. The regulation of phosphodiesterase (PDE) 4B by succinate was also investigated in hepatocytes.

RESULTS

Rg5 inhibited endogenous glucose production in HFD-fed mice. Rg5 reduced cyclic AMP (cAMP) accumulation and inhibited transcriptional regulation of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) by dephosphorylation of the cAMP response element-binding transcription factor in the liver, demonstrating the inhibitory effect on hepatic glucagon response. HFD feeding increased succinate accumulation in the liver due to the reversal of succinate dehydrogenase activation and triggered hypoxia-inducible factor-1α (HIF-1α) induction. Succinate prevented cAMP degradation by inactivating PDE4B, thereby increasing cAMP accumulation in response to glucagon. Knockdown of HIF-1α with small interfering RNA diminished the effect of succinate, indicating that HIF-1α was essential for succinate to inactivate PDE4B. Rg5 inhibited succinate accumulation in hepatocytes by combating fatty acid oxidation, and thus reduced cAMP accumulation by blocking succinate/HIF-1α induction. Rg5 reduced HGP as a consequence of the inhibition of the glucagon response.

CONCLUSIONS/INTERPRETATION

Succinate acted as a metabolic signal to enhance the hepatic glucagon response. Rg5 reduced hepatic succinate accumulation by combating fatty acid oxidation and attenuated the hepatic glucagon response by suppressing succinate/HIF-1α induction, suggesting that succinate-associated HIF-1α induction in hepatocytes might be a therapeutic target in the treatment of diabetes.

Antidepressant-like effects of tetrahydroxystilbene glucoside in mice: Involvement of BDNF signaling cascade in the hippocampus

BACKGROUND AND AIMS

Current antidepressants in clinic need weeks of administration and always have significant limitations. Tetrahydroxystilbene glucoside (TSG) is one of the major bioactive ingredients of Polygonum multiflorum with neuroprotective effects. This study aimed to evaluate the antidepressant effects of TSG in mice.

METHODS

The antidepressant-like effects of TSG in mice were examined in the forced swim test (FST), tail suspension test (TST), and chronic social defeat stress (CSDS) model of depression. The effects of CSDS and TSG on the hippocampal brain-derived neurotrophic factor (BDNF) signaling pathway and neurogenesis were further investigated. Moreover, the pharmacological inhibitors and lentiviral-shRNA were used to explore the antidepressant mechanisms of TSG.

RESULTS

TSG produced antidepressant-like effects in the FST and TST and also reversed the CSDS-induced depressive-like symptoms. Moreover, TSG treatment significantly restored the decreased hippocampal BDNF signaling pathway and neurogenesis in CSDS mice. Importantly, blockade of the hippocampal BDNF system fully abolished the antidepressant-like effects of TSG in mice.

CONCLUSION

In conclusion, TSG produces antidepressant-like effects in mice via enhancement of the hippocampal BDNF system.

Antidepressant-like effects of ginsenoside Rg5 in mice: Involving of hippocampus BDNF signaling pathway

Ginsenoside Rg5 is one of the major bioactive ingredients of Panax ginseng with little toxicity and has been shown to have pharmacological effects on the central nervous system. In this study, we investigated the antidepressant effects of Rg5 in mice models of depression. The effects of Rg5 were first assessed in the forced swimming test (FST) and tail suspension test (TST), and then investigated in the chronic social defeat stress (CSDS) model of depression. The changes in hippocampal brain-derived neurotrophic factor (BDNF) signaling pathway after CSDS and Rg5 treatment were also examined. The tryptophan hydroxylase inhibitor and tyrosine kinase B inhibitor were used to explore the antidepressant mechanisms of Rg5. It was found that Rg5 exhibited antidepressant-like activities in the FST and TST without affecting locomotor activity. Rg5 was also effective in the CSDS model of depression, and restored the CSDS-induced decrease in hippocampal BDNF signaling cascade. Moreover, the usage of the tyrosine kinase B inhibitor blocked the antidepressant effects of Rg5, while the tryptophan hydroxylase inhibitor did not. Collectively, ginsenoside Rg5 has antidepressant activities via the activation of hippocampal BDNF system.

Ginsenoside Rg5 Inhibits Succinate-Associated Lipolysis in Adipose Tissue and Prevents Muscle Insulin Resistance

Endoplasmic reticulum (ER) stress, inflammation, and lipolysis occur simultaneously in adipose dysfunction and contribute to insulin resistance. This study was designed to investigate whether ginsenoside Rg5 could ameliorate adipose dysfunction and prevent muscle insulin resistance. Short-term high-fat diet (HFD) feeding induced hypoxia with ER stress in adipose tissue, leading to succinate accumulation due to the reversal of succinate dehydrogenase (SDH) activity. Rg5 treatment reduced cellular energy charge, suppressed ER stress and then prevented succinate accumulation in adipose tissue. Succinate promoted IL-1β production through NLRP3 inflammasome activation and then increased cAMP accumulation by impairing PDE3B expression, leading to increased lipolysis. Ginsenoside Rg5 treatment suppressed NLRP3 inflammasome activation, preserved PDE3B expression and then reduced cAMP accumulation, contributing to inhibition of lipolysis. Adipose lipolysis increased FFAs trafficking from adipose tissue to muscle. Rg5 reduced diacylglycerol (DAG) and ceramides accumulation, inhibited protein kinase Cθ translocation, and prevented insulin resistance in muscle. In conclusion, succinate accumulation in hypoxic adipose tissue acts as a metabolic signaling to link ER stress, inflammation and cAMP/PKA activation, contributing to lipolysis and insulin resistance. These findings establish a previously unrecognized role of ginsenosides in the regulation of lipid and glucose homeostasis and suggest that adipose succinate-associated NLRP3 inflammasome activation might be targeted therapeutically to prevent lipolysis and insulin resistance.

Changbai Mountain Ginseng (Panax ginseng C.A. Mey) Extract Supplementation Improves Exercise Performance and Energy Utilization and Decreases Fatigue-Associated Parameters in Mice

Changbai Mountain Ginseng (CMG, Panax ginseng C.A. Mey) is a traditional medicine commonly found in Northeast China and grows at elevations of 2000 m or higher in the Changbai Mountain Range. CMG, considered to be a "buried treasure medicine", is priced higher than other types of ginseng. However, few studies have demonstrated the effects of CMG supplementation on exercise performance, physical fatigue, and the biochemical profile. The major compound of CMG extract was characterized by electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Male ICR mice were divided into 3 groups, the vehicle, CMG-1X and CMG-5X groups (n = 8 per group), and respectively administered 0, 5, or 25 mg/kg/day of CMG extract orally for four weeks. HPLC-ESI-MS/MS results showed that the major compound in CMG extract is ginsenoside Ro. CMG extract significantly increased muscle weight and relative muscle weight (%). CMG extract supplementation dose-dependently increased grip strength (p < 0.0001) and endurance swimming time, decreased levels of serum lactate (p < 0.0001), ammonia (p < 0.0001), creatine kinase (CK, p = 0.0002), and blood urea nitrogen (p < 0.0001), and economized glucose levels (p < 0.0001) after acute exercise challenge. The glycogen in the gastrocnemius muscle was significantly increased with CMG extract treatment. Biochemical profile results showed that creatinine and triacylglycerol significantly decreased and total protein and glucose increased with CMG treatment. This is the first report that CMG extract supplementation increases muscle mass, improves exercise performance and energy utilization, and decreases fatigue-associated parameters in vivo. The major component of CMG extract is ginsenoside Ro, which could be a potential bioactive compound for use as an ergogenic aid ingredient by the food industry.

20S-Protopanaxadiol, an aglycosylated ginsenoside metabolite, induces hepatic stellate cell apoptosis through liver kinase B1-AMP-activated protein kinase activation

BACKGROUND

Previously, we reported that Korean Red Ginseng inhibited liver fibrosis in mice and reduced the expressions of fibrogenic genes in hepatic stellate cells (HSCs). The present study was undertaken to identify the major ginsenoside responsible for reducing the numbers of HSCs and the underlying mechanism involved.

METHODS

Using LX-2 cells (a human immortalized HSC line) and primary activated HSCs, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) assays were conducted to examine the cytotoxic effects of ginsenosides. H₂O₂ productions, glutathione contents, lactate dehydrogenase activities, mitochondrial membrane permeabilities, apoptotic cell subpopulations, caspase-3/-7 activities, transferase dUTP nick end labeling (TUNEL) staining, and immunoblot analysis were performed to elucidate the molecular mechanism responsible for ginsenoside-mediated cytotoxicity. Involvement of the AMP-activated protein kinase (AMPK)-related signaling pathway was examined using a chemical inhibitor and small interfering RNA (siRNA) transfection.

RESULTS AND CONCLUSION

Of the 11 ginsenosides tested, 20S-protopanaxadiol (PPD) showed the most potent cytotoxic activity in both LX-2 cells and primary activated HSCs. Oxidative stress-mediated apoptosis induced by 20S-PPD was blocked by N-acetyl-l-cysteine pretreatment. In addition, 20S-PPD concentration-dependently increased the phosphorylation of AMPK, and compound C prevented 20S-PPD-induced cytotoxicity and mitochondrial dysfunction. Moreover, 20S-PPD increased the phosphorylation of liver kinase B1 (LKB1), an upstream kinase of AMPK. Likewise, transfection of LX-2 cells with LKB1 siRNA reduced the cytotoxic effect of 20S-PPD. Thus, 20S-PPD appears to induce HSC apoptosis by activating LKB1-AMPK and to be a therapeutic candidate for the prevention or treatment of liver fibrosis.

Effect of Korean Red Ginseng in chronic liver disease

Chronic liver disease, one of the most common diseases, typically arises from nonalcoholic fatty liver disease, alcoholic liver disease, chronic viral hepatitis, or hepatocellular carcinoma. Therefore, there is a pressing need for improved treatment strategies. Korean Red Ginseng has been known to have positive effects on liver disease and liver function. In this paper, we summarize the current knowledge on the beneficial effects of Korean Red Ginseng on chronic liver disease, a condition encompassing nonalcoholic fatty liver disease, alcoholic liver disease, chronic viral hepatitis, and hepatocellular carcinoma, as supported by experimental evaluation and clinical investigation.

PGC-1α, glucose metabolism and type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by glucose metabolic disturbance. A number of transcription factors and coactivators are involved in this process. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) is an important transcription coactivator regulating cellular energy metabolism. Accumulating evidence has indicated that PGC-1α is involved in the regulation of T2DM. Therefore, a better understanding of the roles of PGC-1α may shed light on more efficient therapeutic strategies. Here, we review the most recent progress on PGC-1α and discuss its regulatory network in major glucose metabolic tissues such as the liver, skeletal muscle, pancreas and kidney. The significant associations between PGC-1α polymorphisms and T2DM are also discussed in this review.

Aged ginseng (Panax ginseng Meyer) reduces blood glucose levels and improves lipid metabolism in high fat diet-fed mice

Aged ginseng is unpeeled ginseng root that has been dried and heat-treated in an oven at 80°C for 14 days. The effects of aged ginseng, in comparison with white and red ginseng, on the lipid and glucose metabolism in high fat-fed mice were investigated. C57BL/6N mice were randomly divided into six dietary groups of normal control, high fat, and high fat supplemented with white, red, aged four-year old, and aged five-year old ginseng. After 8 weeks, ginseng counteracted high fat dietinduced body weight gain, hyperlipidemia, and hyperglycemia via a mechanism involving modulation of hepatic lipogenesis, adipokine production, and glucose-regulating enzyme activities. Aged ginseng showed greater antihyperlipidemic and antihyperglycemic activities than white ginseng and exhibited physiological effects similar to red ginseng, perhaps due to a relatively high ginsenoside content. Aged ginseng can be beneficial as a functional food.

The Efficacy of Ginseng-Related Therapies in Type 2 Diabetes Mellitus: An Updated Systematic Review and Meta-analysis

Few randomized clinical trials have evaluated the efficacy of ginseng in patients with type 2 diabetes mellitus (T2DM). The current meta-analysis evaluated the ginseng-induced improvement in glucose control and insulin sensitivity in patients with type-2 diabetes or impaired glucose tolerance.Randomized clinical trials comparing ginseng supplementation versus control, in patients with T2DM or impaired glucose tolerance, were hand-searched from Medline, Cochrane, and Google Scholar databases by 2 independent reviewers using the terms "type 2 diabetes/diabetes/diabetic, impaired glucose tolerance, and ginseng/ginsenoside(s)." The primary outcome analyzed was the change in HbA1c, whereas the secondary outcomes included fasting glucose, postprandial glucose, fasting insulin, postprandial insulin, insulin resistance Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), triglycerides, total cholesterol, low density lipoprotein (LDL), and high density lipoprotein (HDL).Of the 141 studies identified, 8 studies were chosen for the current meta-analysis. The average number of patients, age, and sex distribution among the groups were comparable. Results reveal no significant difference in HbA1c levels between the ginseng supplementation and the control groups (pooled standardized difference in means = -0.148, 95% CI: -0.637 to 0.228, P = 0.355). Ginseng supplementation improved fasting glucose, postprandial insulin, and HOMA-IR levels, though no difference in postprandial glucose or fasting insulin was observed among the groups. Similarly, triglycerides, total cholesterol, and LDL levels showed significant difference between the treatment groups, while no difference in HDL was seen. In addition, ginseng-related therapy was ineffective in decreasing the fasting glucose levels in patients treated with oral hypoglycemic agents or insulin.The present results establish the benefit of ginseng supplementation in improving glucose control and insulin sensitivity in patients with T2DM or impaired glucose intolerance.

Regulation of AMP-activated protein kinase by natural and synthetic activators

The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is almost universally expressed in eukaryotic cells. While it appears to have evolved in single-celled eukaryotes to regulate energy balance in a cell-autonomous manner, during the evolution of multicellular animals its role has become adapted so that it also regulates energy balance at the whole body level, by responding to hormones that act primarily on the hypothalamus. AMPK monitors energy balance at the cellular level by sensing the ratios of AMP/ATP and ADP/ATP, and recent structural analyses of the AMPK heterotrimer that have provided insight into the complex mechanisms for these effects will be discussed. Given the central importance of energy balance in diseases that are major causes of morbidity or death in humans, such as type 2 diabetes, cancer and inflammatory disorders, there has been a major drive to develop pharmacological activators of AMPK. Many such activators have been described, and the various mechanisms by which these activate AMPK will be discussed. A particularly large class of AMPK activators are natural products of plants derived from traditional herbal medicines. While the mechanism by which most of these activate AMPK has not yet been addressed, I will argue that many of them may be defensive compounds produced by plants to deter infection by pathogens or grazing by insects or herbivores, and that many of them will turn out to be inhibitors of mitochondrial function.

New Insights into Orphan Nuclear Receptor SHP in Liver Cancer

Small heterodimer partner (SHP; NR0B2) is a unique orphan nuclear receptor (NR) that contains a putative ligand-binding domain but lacks a DNA-binding domain. SHP is a transcriptional corepressor affecting diverse metabolic processes including bile acid synthesis, cholesterol and lipid metabolism, glucose and energy homeostasis, and reproductive biology via interaction with multiple NRs and transcriptional factors (TFs). Hepatocellular carcinoma (HCC) is one of the most deadly human cancers worldwide with few therapeutic options and poor prognosis. Recently, it is becoming clear that SHP plays an antitumor role in the development of liver cancer. In this review, we summarize the most recent findings regarding the new SHP interaction partners, new structural insights into SHP’s gene repressing activity, and SHP protein posttranslational modifications by bile acids. We also discuss the pleiotropic role of SHP in regulating cell proliferation, apoptosis, DNA methylation, and inflammation that are related to antitumor role of SHP in HCC. Improving our understanding of SHP’s antitumor role in the development of liver cancer will provide new insights into developing novel treatments or prevention strategies. Future research will focus on developing more efficacious and specific synthetic SHP ligands for pharmaceutical applications in liver cancer and several metabolic diseases such as hypercholesterolemia, obesity, diabetes, and fatty liver disease.

Novel Approach to Identify Potential Bioactive Plant Metabolites: Pharmacological and Metabolomics Analyses of Ethanol and Hot Water Extracts of Several Canadian Medicinal Plants of the Cree of Eeyou Istchee

We evaluated and compared the antidiabetic potential and molecular mechanisms of 17 Cree plants' ethanol extracts (EE) and hot water extracts (HWE) on glucose homeostasis in vitro and used metabolomics to seek links with the content of specific phytochemicals. Several EE of medical plants stimulated muscle glucose uptake and inhibited hepatic G6Pase activity. Some HWE partially or completely lost these antidiabetic activities in comparison to EE. Only R. groenlandicum retained similar potential between EE and HWE in both assays. In C2C12 muscle cells, EE of R. groenlandicum, A. incana and S. purpurea stimulated glucose uptake by activating AMP-activated protein kinase (AMPK) pathway and increasing glucose transporter type 4 (GLUT4) expression. In comparison to EE, HWE of R. groenlandicum exhibited similar activities; HWE of A. incana completely lost its effect on all parameters; interestingly, HWE of S. purpurea activated insulin pathway instead of AMPK pathway to increase glucose uptake. In the liver, for a subset of 5 plants, HWE and EE activated AMPK pathway whereas the EE and HWE of S. purpurea and K. angustifolia also activated insulin pathways. Quercetin-3-O-galactoside and quercetin 3-O-α-L-arabinopyranoside, were successfully identified by discriminant analysis as biomarkers of HWE plant extracts that stimulate glucose uptake in vitro. More importantly, the latter compound was not identified by previous bioassay-guided fractionation.

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.

Identification and characterization of a ginsenoside-transforming β-glucosidase from Pseudonocardia sp. Gsoil 1536 and its application for enhanced production of minor ginsenoside Rg2(S)

The ginsenoside Rg₂(S), which is one of the pharmaceutical components of ginseng, is known to have neuroprotective, anti-inflammation, and anti-diabetic effects. However, the usage of ginsenoside Rg₂(S) is restricted owing to the small amounts found in white and red ginseng. To enhance the production of ginsenoside Rg₂(S) as a 100 gram unit with high specificity, yield, and purity, an enzymatic bioconversion method was developed to adopt the recombinant glycoside hydrolase (BglPC28), which is a ginsenoside-transforming recombinant β-glucosidase from Pseudonocardia sp. strain Gsoil 1536. The gene, termed bglPC28, encoding β-glucosidase (BglPC28) belonging to the glycoside hydrolase family 3 was cloned. bglPC28 consists of 2,232 bp (743 amino acid residues) with a predicted molecular mass of 78,975 Da. This enzyme was overexpressed in Escherichia coli BL21(DE3) using a GST-fused pGEX 4T-1 vector system. The optimum conditions of the recombinant BglPC28 were pH 7.0 and 37°C. BglPC28 can effectively transform the ginsenoside Re to Rg₂(S); the K_m values of PNPG and Re were 6.36±1.10 and 1.42±0.13 mM, respectively, and the V_max values were 40.0±2.55 and 5.62±0.21 µmol min⁻¹ mg⁻¹ of protein, respectively. A scaled-up biotransformation reaction was performed in a 10 L jar fermenter at pH 7.0 and 30°C for 12 hours with a concentration of 20 mg/ml of ginsenoside Re from American ginseng roots. Finally, 113 g of Rg₂(S) was produced from 150 g of Re with 84.0±1.1% chromatographic purity. These results suggest that this enzymatic method could be usefully exploited in the preparation of ginsenoside Rg₂(S) in the cosmetics, functional food, and pharmaceutical industries.

AMP-activated protein kinase: maintaining energy homeostasis at the cellular and whole-body levels

The adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway arose early during evolution of eukaryotic cells, when it appears to have been involved in the response to glucose starvation and perhaps also in monitoring the output of the newly acquired mitochondria. Due to the advent of hormonal regulation of glucose homeostasis, glucose starvation is a less frequent event for mammalian cells than for single-celled eukaryotes. Nevertheless, the AMPK system has been preserved in mammals where, by monitoring cellular AMP:adenosine triphosphate (ATP) and adenosine diphosphate (ADP):ATP ratios and balancing the rates of catabolism and ATP consumption, it maintains energy homeostasis at a cell-autonomous level. In addition, hormones involved in maintaining energy balance at the whole-body level interact with AMPK in the hypothalamus. AMPK is activated by two widely used clinical drugs, metformin and aspirin, and also by many natural products of plants that are either derived from traditional medicines or are promoted as "nutraceuticals."

Panax red ginseng extract regulates energy expenditures by modulating PKA dependent lipid mobilization in adipose tissue

Regulation of balance between lipid accumulation and energy consumption is a critical step for the maintenance of energy homeostasis. Here, we show that Panax red ginseng extract treatments increased energy expenditures and prevented mice from diet induced obesity. Panax red ginseng extracts strongly activated Hormone Specific Lipase (HSL) via Protein Kinase A (PKA). Since activation of HSL induces lipolysis in WAT and fatty acid oxidation in brown adipose tissue (BAT), these results suggest that Panax red ginseng extracts reduce HFD induced obesity by regulating lipid mobilization.