Berberine inhibits hepatic gluconeogenesis via the LKB1-AMPK-TORC2 signaling pathway in streptozotocin-induced diabetic rats

Berberine Metabolites Stimulate GLP-1 Secretion by Alleviating Oxidative Stress and Mitochondrial Dysfunction

Berberine (BBR) is a principal component of Rhizoma coptidis known for its therapeutic potential in treating diseases such as type 2 diabetes mellitus (T2DM) and obesity. Despite the trace levels of BBR in plasma, it's believed that its metabolites play a pivotal role in its biological activities. While BBR is recognized to promote GLP-1 production in intestinal L cells, the cytoprotective effects of its metabolites on these cells are yet to be explored. The present study investigates the effects of BBR metabolites on GLP-1 secretion and the underlying mechanisms. Our results revealed that, out of six BBR metabolites, berberrubine (BBB) and palmatine (PMT) significantly increased the production and glucose-stimulated secretion of GLP-1 in GLUTag cells. Notably, both BBB and PMT could facilitate GLP-1 and insulin secretion and enhance glucose tolerance in standard mice. Moreover, a single dose of PMT could markedly increase plasma GLP-1 and improve glucose tolerance in mice with obesity induced by a high-fat diet. In palmitic acid or TNF[Formula: see text]-treated GLUTag cells, BBB and PMT alleviated cell death, oxidative stress, and mitochondrial dysfunction. Furthermore, they could effectively reverse inflammation-induced inhibition of the Akt signaling pathway. In general, these insights suggest that the beneficial effects of orally administered BBR on GLP-1 secretion are largely attributed to the pharmacological activity of BBB and PMT by their above cytoprotective effects on L cells, which provide important ideas for stimulating GLP-1 secretion and the treatment of T2DM.

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.

Lithium and exercise ameliorate insulin-deficient hyperglycemia by independently attenuating pancreatic α-cell mass and hepatic gluconeogenesis

As in type 1 diabetes, the loss of pancreatic β-cells leads to insulin deficiency and the subsequent development of hyperglycemia. Exercise has been proposed as a viable remedy for hyperglycemia. Lithium, which has been used as a treatment for bipolar disorder, has also been shown to improve glucose homeostasis under the conditions of obesity and type 2 diabetes by enhancing the effects of exercise on the skeletal muscles. In this study, we demonstrated that unlike in obesity and type 2 diabetic conditions, under the condition of insulin-deficient type 1 diabetes, lithium administration attenuated pancreatic a-cell mass without altering insulin-secreting β-cell mass, implying a selective impact on glucagon production. Additionally, we also documented that lithium downregulated the hepatic gluconeogenic program by decreasing G6Pase protein levels and upregulating AMPK activity. These findings suggest that lithium's effect on glucose metabolism in type 1 diabetes is mediated through a different mechanism than those associated with exerciseinduced metabolic changes in the muscle. Therefore, our research presents the novel therapeutic potential of lithium in the treatment of type 1 diabetes, which can be utilized along with insulin and independently of exercise.

A Mechanistic Review on How Berberine Use Combats Diabetes and Related Complications: Molecular, Cellular, and Metabolic Effects

Berberine (BBR) is an isoquinoline alkaloid that can be extracted from herbs such as Coptis, Phellodendron, and Berberis. BBR has been widely used as a folk medicine to treat various disorders. It is a multi-target drug with multiple mechanisms. Studies have shown that it has antioxidant and anti-inflammatory properties and can also adjust intestinal microbial flora. This review focused on the promising antidiabetic effects of BBR in several cellular, animal, and clinical studies. Based on previous research, BBR significantly reduced levels of fasting blood glucose, hemoglobin A1C, inflammatory cytokines, and oxidative stress markers. Furthermore, BBR stimulated insulin secretion and improved insulin resistance through different pathways, including up-regulation of protein expression of proliferator-activated receptor (PPAR)-γ, glucose transporter (GLUT) 4, PI3K/AKT, and AMP-activated protein kinase (AMPK) activation. Interestingly, it was demonstrated that BBR has protective effects against diabetes complications, such as diabetic-induced hepatic damage, cardiovascular disorders, nephropathy, and neuropathy. Furthermore, multiple clinical trial studies have emphasized the ameliorative effects of BBR in type 2 diabetic patients.

Role of glycolysis in diabetic atherosclerosis

Diabetes mellitus is a kind of typical metabolic disorder characterized by elevated blood sugar levels. Atherosclerosis (AS) is one of the most common complications of diabetes. Modern lifestyles and trends that promote overconsumption and unhealthy practices have contributed to an increase in the annual incidence of diabetic AS worldwide, which has created a heavy burden on society. Several studies have shown the significant effects of glycolysis-related changes on the occurrence and development of diabetic AS, which may serve as novel thera-peutic targets for diabetic AS in the future. Glycolysis is an important metabolic pathway that generates energy in various cells of the blood vessel wall. In particular, it plays a vital role in the physiological and pathological activities of the three important cells, Endothelial cells, macrophages and vascular smooth muscle cells. There are lots of similar mechanisms underlying diabetic and common AS, the former is more complex. In this article, we describe the role and mechanism underlying glycolysis in diabetic AS, as well as the therapeutic targets, such as trained immunity, microRNAs, gut microbiota, and associated drugs, with the aim to provide some new perspectives and potentially feasible programs for the treatment of diabetic AS in the foreseeable future.

Production of Food-Derived Bioactive Peptides with Potential Application in the Management of Diabetes and Obesity: A Review

The prevalence of diabetes mellitus and obesity is increasing worldwide. Bioactive peptides are naturally present in foods or in food-derived proteins. Recent research has shown that these bioactive peptides have an array of possible health benefits in the management of diabetes and obesity. First, this review will summarize the top-down and bottom-up production methods of the bioactive peptides from different protein sources. Second, the digestibility, bioavailability, and metabolic fate of the bioactive peptides are discussed. Last, the present review will discuss and explore the mechanisms by which these bioactive peptides help against obesity and diabetes based on in vitro and in vivo studies. Although several clinical studies have demonstrated that bioactive peptides are beneficial in alleviating diabetes and obesity, more double-blind randomized controlled trials are needed in the future. This review has provided novel insights into the potential of food-derived bioactive peptides as functional foods or nutraceuticals to manage obesity and diabetes.

Berberine Ameliorates Metabolic-Associated Fatty Liver Disease Mediated Metabolism Disorder and Redox Homeostasis by Upregulating Clock Genes: Clock and Bmal1 Expressions

Metabolic-associated fatty liver disease (MAFLD) is one of the most common chronic liver diseases, which in turn triggers mild inflammation, metabolic dysfunction, fibrosis, and even cancer. Accumulating evidence has suggested that Berberine (BBR) could significantly improve MAFLD progression. Clock and Bmal1 as heterodimer proteins highly participated in the development of MAFLD, but whether BBR targets Clock and Bmal1 in MAFLD remains poorly understood. The result suggested that the protein levels of Clock and Bmal1 were decreased in MAFLD mice, which was negatively correlated with elevated reactive oxygen species (ROS) accumulation, the H₂O₂ level, liver inflammation, metabolic dysfunction, and insulin resistance. The mRNA and protein levels of Clock and Bmal1 were also decreased in glucosamine-induced HepG2 cells, which were are negatively related to glucose uptake, the ROS level, and the H₂O₂ level. More importantly, Bmal1 siRNA could mimic the effect of glucosamine in HepG2 cells. Interestingly, Berberine (BBR) could rescue metabolism disorder and redox homeostasis through enhancing Clock and Bmal1 expression in vivo and in vitro. Therefore, BBR might be an effective natural compound for alleviating redox homeostasis, metabolism disorder, and liver pathological changes in MAFLD by activating Clock and Bmal1 expression.

A Review of Fibraurea tinctoria and Its Component, Berberine, as an Antidiabetic and Antioxidant

Diabetes mellitus is a group of metabolic disorders characterized by hyperglycemia caused by resistance to insulin action, inadequate insulin secretion, or excessive glucagon production. Numerous studies have linked diabetes mellitus and oxidative stress. People with diabetes usually exhibit high oxidative stress due to persistent and chronic hyperglycemia, which impairs the activity of the antioxidant defense system and promotes the formation of free radicals. Recently, several studies have focused on exploring natural antioxidants to improve diabetes mellitus. Fibraurea tinctoria has long been known as the native Borneo used in traditional medicine to treat diabetes. Taxonomically, this plant is part of the Menispermaceae family, widely known for producing various alkaloids. Among them are protoberberine alkaloids such as berberine. Berberine is an isoquinoline alkaloid with many pharmacological activities. Berberine is receiving considerable interest because of its antidiabetic and antioxidant activities, which are based on many biochemical pathways. Therefore, this review explores the pharmacological effects of Fibraurea tinctoria and its active constituent, berberine, against oxidative stress and diabetes, emphasizing its mechanistic aspects. This review also summarizes the pharmacokinetics and toxicity of berberine and in silico studies of berberine in several diseases and its protein targets.

Study of Hypoglycemic Activity of Novel 9-N-alkyltetrahydroberberine Derivatives

Novel 9-N-alkyltetrahydroberberine derivatives were synthesized, among which, based on the results of OGTT, one compound containing the longest aliphatic substituent was selected for study in mice C57BL/6^Ay, which demonstrate obesity, impaired glucose tolerance, and concomitant liver non-alcoholic fatty disease. Administration of this substance at a dose of 15 mg/kg for four weeks improved the insulin sensitivity of mice, which resulted in a decrease in fasting glucose levels and improved the tolerance of mice to OGTT glucose loading. A decrease in the level of lactate in the blood and a decrease in the amount of glucokinase in the liver were also found. The introduction of compound 3c did not have a toxic effect on animals based on biochemical data, histological analysis, and measurements of general parameters such as body weight and feed intake. Thus, the 9-N-heptyltetrahydroberberine derivative showed prominent hypoglycemic effects, which makes it promising to obtain and study other derivatives with longer substituents.

An Overview of Herbal-Based Antidiabetic Drug Delivery Systems: Focus on Lipid- and Inorganic-Based Nanoformulations

Diabetes is a metabolic pathology with chronic high blood glucose levels that occurs when the pancreas does not produce enough insulin or the body does not properly use the insulin it produces. Diabetes management is a puzzle and focuses on a healthy lifestyle, physical exercise, and medication. Thus far, the condition remains incurable; management just helps to control it. Its medical treatment is expensive and is to be followed for the long term, which is why people, especially from low-income countries, resort to herbal medicines. However, many active compounds isolated from plants (phytocompounds) are poorly bioavailable due to their low solubility, low permeability, or rapid elimination. To overcome these impediments and to alleviate the cost burden on disadvantaged populations, plant nanomedicines are being studied. Nanoparticulate formulations containing antidiabetic plant extracts or phytocompounds have shown promising results. We herein aimed to provide an overview of the use of lipid- and inorganic-based nanoparticulate delivery systems with plant extracts or phytocompounds for the treatment of diabetes while highlighting their advantages and limitations for clinical application. The findings from the reviewed works showed that these nanoparticulate formulations resulted in high antidiabetic activity at low doses compared to the corresponding plant extracts or phytocompounds alone. Moreover, it was shown that nanoparticulate systems address the poor bioavailability of herbal medicines, but the lack of enough preclinical and clinical pharmacokinetic and/or pharmacodynamic trials still delays their use in diabetic patients.

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.

Expatiating the Pharmacological and Nanotechnological Aspects of the Alkaloidal Drug Berberine: Current and Future Trends

Traditionally, herbal compounds have been the focus of scientific interest for the last several centuries, and continuous research into their medicinal potential is underway. Berberine (BBR) is an isoquinoline alkaloid extracted from plants that possess a broad array of medicinal properties, including anti-diarrheal, anti-fibrotic, antidiabetic, anti-inflammatory, anti-obesity, antihyperlipidemic, antihypertensive, antiarrhythmic, antidepressant, and anxiolytic effects, and is frequently utilized as a traditional Chinese medicine. BBR promotes metabolisms of glucose and lipids by activating adenosine monophosphate-activated protein kinase, stimulating glycolysis and inhibiting functions of mitochondria; all of these ameliorate type 2 diabetes mellitus. BBR has also been shown to have benefits in congestive heart failure, hypercholesterolemia, atherosclerosis, non-alcoholic fatty liver disease, Alzheimer’s disease, and polycystic ovary syndrome. BBR has been investigated as an interesting pharmacophore with the potential to contribute significantly to the research and development of novel therapeutic medicines for a variety of disorders. Despite its enormous therapeutic promise, the clinical application of this alkaloid was severely limited because of its unpleasant pharmacokinetic characteristics. Poor bioavailability, limited absorption, and poor water solubility are some of the obstacles that restricted its use. Nanotechnology has been suggested as a possible solution to these problems. The present review aims at recent updates on important therapeutic activities of BBR and different types of nanocarriers used for the delivery of BBR in different diseases.

MDM2-mediated ubiquitination of LKB1 contributes to the development of diabetic cataract

Diabetic cataract (DC) is a common complication of diabetes mellitus. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a crucial event in the development of DC. Murine double minute 2 (MDM2) is an E3 ubiquitin ligase that promotes EMT by regulating diverse targets. However, little is known about how MDM2 is involved in the pathogenesis of DC. We found the mRNA and protein levels of MDM2 were up-regulated in the lens of DC patients and rats. Thus, high glucose (HG)-induced human lens epithelial cells (HLECs) were constructed for further investigation. The results showed that the level of MDM2 was increased in HG-cultured HLECs, and the MDM2 knockdown alleviated HG-induced abnormal migration, EMT, and oxidative stress damage. Moreover, co-immunoprecipitation and ubiquitination assays demonstrated that MDM2 down-regulated LKB1 expression by ubiquitination degradation. LKB1 was found to be lower expressed in human and rat DC lenses, and HG-stimulated HLECs. Also, LKB1 overexpression mitigated HG-induced dysfunction of HLECs. Finally, our data showed that the changes related to EMT and oxidative stress induced by MDM2 knockdown were restored by down-regulation of LKB1. Together, MDM2 may involve in the pathogenesis of DC through down-regulating LKB1. MDM2 might be an effective therapeutical target of DC.

Understanding of Diabetes in Tibetan, Mongolian, Miao, Dai, Uygur, and Yi Medicine and Collation of Prevention and Cure Medicines

Diabetes seriously endangers human health and causes a huge economic burden. With the improvement of people's living standard, the prevalence of diabetes is getting higher and higher, and age is becoming younger. It is an increasingly serious global problem. Therefore, it is imperative to find the drugs to treat diabetes. Ethnic medicine is an important part of the world's medicinal treasure house and has its own unique system. This study systematically combined the theoretical understanding of the prevention and treatment of diabetes of Tibetan, Mongolian, Miao, Dai, Uygur, and Yi people by searching the existing literature studies published until 2021, library collection resources (related ethnic monographs, medical books, standards of medicinal materials, etc.), CNKI, PubMed, and other databases and collected and sorted the relevant medicines. A total of 112 kinds of ethnic medicines for the prevention and treatment of diabetes have been discovered, including plant medicines (105 kinds), animal medicines (6 kinds), and fungal medicines (1 kind). The composition of family and genus, medicinal parts, and life forms of medicinal plants were analyzed, and the number of drugs used in the prevention and treatment of diabetes in each ethnic group was statistically analyzed. The results showed that Rosaceae was at the top of the list, and the drugs used in underground parts accounted for 33.90% of the total, and the medicinal plants were mainly herbaceous, and the Mongolians have the largest number of diabetes medicines. In addition, CNKI, PubMed, and other databases selected “medicinal materials name,” “diabetes,” and “hypoglycemia” as keywords, the top 30 medicinal materials reported in existing literature were listed, and their Chinese name, the Latin name of the original plant, family and genus, nationality used, medicinal parts, and active ingredients related to the prevention and treatment of diabetes were introduced in detail. Among the 30 medicines, Astragalus membranaceus, Pueraria lobata, and Coptis chinensis are the most commonly used. Through literature research, this study summarized the existing theories of ethnic medicine for the prevention and treatment of diabetes, collected and sorted out ethnic medicine, clarified the potential mechanism of ethnic medicine, and provided effective data compilation. Ethnic medicine has a long history of treating diabetes, and there are abundant medicinal materials, to provide a new idea and basis for treating diabetes.

Flavonoids, alkaloids and terpenoids: a new hope for the treatment of diabetes mellitus

Diabetes mellitus is a metabolic syndrome characterized by a hyperglycemic state and multi-organ failure. Millions of people worldwide are suffering from this deadly disease taking a hit on their pocket and mental health in the name of its treatment. Modern medical practices with new technological advancements and discoveries have made revolutionary changes in the treatment. But, unfortunately, Glucose-lowering drugs used have many accompanying effects such as chronic vascular disease, renal malfunction, liver disease and, many skin problems. These complications have made us think about alternative treatments for diabetes with minimum or no side effects. Nowadays, in addition to modern medicine, herbal treatment has been suggested to treat diabetes mellitus. These herbal medicines contain biological macromolecules such as flavonoids, Terpenoids, glycosides, and alkaloids, which show versatile anti-diabetic effects. These phytochemicals are generally considered safe, and naturally occurring compounds have a potential role in preventing or controlling diabetes mellitus. The underlying mechanism of their anti-diabetic effects includes improvement in insulin secretion, decrease in insulin resistance, enhanced liver glycogen synthesis, antioxidant and anti-inflammatory activities. In this review, we have focused on the mechanism of various phytochemicals targeting hyperglycemia and its underlying pathogenesis.

Potencjalne możliwości wykorzystania berberyny w przeciwdziałaniu insulinooporności i w cukrzycy typu 2

Insulinooporność to stan zmniejszonej wrażliwości tkanek docelowych na działanie insuliny, mimo jej prawidłowego lub podwyższonego stężenia w surowicy krwi. Jest ważnym czynnikiem w patogenezie zespołu metabolicznego, w tym stanu przedcukrzycowego i cukrzycy typu 2, a także chorób sercowo-naczyniowych oraz zespołu policystycznych jajników. Wzrasta zainteresowanie wykorzystaniem środków pochodzenia roślinnego w leczeniu pacjentów z chorobami metabolicznymi. Jednymi z nich są rośliny z rodziny berberysowatych zawierające alkaloidy izochinolinowe, takie jak berberyna. Sugeruje się, iż berberyna może wpływać na zmniejszenie insulinooporności, gospodarkę węglowodanową oraz metabolizm lipidów. Naukowcy wykazali, że ten roślinny alkaloid może tłumić różnicowanie adipocytów i wspomagać redukcję masy ciała. Inne właściwości berberyny obejmują działanie hipotensyjne oraz ochronne wobec śródbłonka naczyniowego. W artykule skoncentrowano się przede wszystkim na przedstawieniu potencjalnych możliwości wykorzystania berberyny w przeciwdziałaniu insulinooporności w cukrzycy typu 2.

Berberine improves ovulation and endometrial receptivity in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a clinical syndrome with reproductive and endocrine disorders. Berberine is a monomer from Chinese herbs such as Coptis chinensis, whose effect on improving ovulation and endometrial receptivity of PCOS is uncertain.

PURPOSE

To evaluate the effect of berberine on improving PCOS and explore the mechanism.

METHODS

The rat model of PCOS was induced by intraperitoneal injection of testosterone propionate. Then they was divided into model (Mod) group, low-dose of berberine (BL) group, high-dose of berberine (BH) group and metformin (Met) group as well as a control (Con) group was established. Ovary morphology, hormone level, glucolipid metabolism were measured. UID-mRNA-seq of ovary tissue was conducted to seek the mechanism of berberine on improving ovulation. Three biomarkers of endometrial receptivity were also examined in endometrium by immunohistochemistry.

RESULTS

The number of cystic follicles was increased while the number of corpus luteum was decreased in the rats of Mod group. These changes could be reversed by high-dose of berberine intervention. Berberine could also decrease the levels of serum luteinizing hormone (LH) and total cholesterol (TC) in PCOS rats. Meanwhile, berberine improved the impairment of abnormal oral glucose tolerance without affecting fasting insulin level and Homeostasis model assessment-insulin resistance (HOMA-IR). Luteinizing hormone/ choriogonadotropin receptor (LHCGR) and cytochrome P450 Family 19 Subfamily A Member 1 (CYP19A1) were focused via RNA-seq of ovary. Protein expression in ovary and mRNA expression in granulosa cell of LHCGR and CYP19A1 were decreased in Mod group and rescued by the intervention of berberine. A decrease of endometrial thickness and an increase of integrin αvβ3 and lysophosphatidic acid receptor 3 (LPAR3) protein expression were observed in Mod group, which could be also reversed by berberbine.

CONCLUSIONS

Berberine could improve ovulation in PCOS and the mechanism might be associated with up-regulating LHCGR and CYP19A1. Berberine could also improve endometrial receptivity through down-regualting αvβ3 and LPAR3.

Pharmacokinetics and Pharmacological Activities of Berberine in Diabetes Mellitus Treatment

Traditional Chinese medicine (TCM) has good clinical application prospects in diabetes treatment. In addition, TCM is less toxic and/or has fewer side effects and provides various therapeutic effects. Berberine (BBR) is isolated as the main component in many TCM kinds (e.g., Rhizoma Coptidis and Berberidis Cortex). Furthermore, BBR can reduce blood sugar and blood fat, alleviate inflammation, and improve the state of patients. Based on the recent study results of BBR in diabetes treatment, the BBR pharmacokinetics and mechanism on diabetes are mainly studied, and the specific molecular mechanism of related experimental BBR is systematically summarized and analyzed. Clinical studies have proved that BBR has a good therapeutic effect on diabetes, suggesting that BBR may be a promising drug candidate for diabetes. More detailed BBR mechanisms and pathways of BBR need to be studied further in depth, which will help understand the BBR pharmacology in diabetes treatment.

Plants Secondary Metabolites as Blood Glucose-Lowering Molecules

Recently, significant advances in modern medicine and therapeutic agents have been achieved. However, the search for effective antidiabetic drugs is continuous and challenging. Over the past decades, there has been an increasing body of literature related to the effects of secondary metabolites from botanical sources on diabetes. Plants-derived metabolites including alkaloids, phenols, anthocyanins, flavonoids, stilbenoids, saponins, tannins, polysaccharides, coumarins, and terpenes can target cellular and molecular mechanisms involved in carbohydrate metabolism. In addition, they can grant protection to pancreatic beta cells from damage, repairing abnormal insulin signaling, minimizing oxidative stress and inflammation, activating AMP-activated protein kinase (AMPK), and inhibiting carbohydrate digestion and absorption. Studies have highlighted many bioactive naturally occurring plants' secondary metabolites as candidates against diabetes. This review summarizes the current knowledge compiled from the latest studies published during the past decade on the mechanism-based action of plants-derived secondary metabolites that can target various metabolic pathways in humans against diabetes. It is worth mentioning that the compiled data in this review will provide a guide for researchers in the field, to develop candidates into environment-friendly effective, yet safe antidiabetics.

Multi-Pharmacology of Berberine in Atherosclerosis and Metabolic Diseases: Potential Contribution of Gut Microbiota

Atherosclerosis (AS), especially atherosclerotic cardiovascular diseases (ASCVDs), and metabolic diseases (such as diabetes, obesity, dyslipidemia, and nonalcoholic fatty liver disease) are major public health issues worldwide that seriously threaten human health. Exploring effective natural product-based drugs is a promising strategy for the treatment of AS and metabolic diseases. Berberine (BBR), an important isoquinoline alkaloid found in various medicinal plants, has been shown to have multiple pharmacological effects and therapeutic applications. In view of its low bioavailability, increasing evidence indicates that the gut microbiota may serve as a target for the multifunctional effects of BBR. Under the pathological conditions of AS and metabolic diseases, BBR improves intestinal barrier function and reduces inflammation induced by gut microbiota-derived lipopolysaccharide (LPS). Moreover, BBR reverses or induces structural and compositional alterations in the gut microbiota and regulates gut microbe-dependent metabolites as well as related downstream pathways; this improves glucose and lipid metabolism and energy homeostasis. These findings at least partly explain the effect of BBR on AS and metabolic diseases. In this review, we elaborate on the research progress of BBR and its mechanisms of action in the treatment of AS and metabolic diseases from the perspective of gut microbiota, to reveal the potential contribution of gut microbiota to the multifunctional biological effects of BBR.

Potential antidiabetic activity of benzimidazole derivative albendazole and lansoprazole drugs in different doses in experimental type 2 diabetic rats

Background/aim

The aim of this study is to determine the effects of different concentrations of albendazole and lansoprazole, which were benzimidazole derivatives, on endocrinologic and biochemical parameters in experimental type 2 diabetic (T2D) rats.

Materials and methods

In this study, 46 male Wistar Albino rats were used. Animals were divided as healthy control (0.1 mL/rat/day saline, s.c, n = 6), diabetes control (0.1 mL/rat/day saline, s.c, n = 8), diabetes+low-dose albendazole (5 mg/kg, oral, n = 8), diabetes+high- dose albendazole (10 mg/kg, oral n = 8), diabetes+low-dose lansoprazole (15 mg/kg, subcutaneous, n = 8), and diabetes+high-dose lansoprazole (30 mg/kg, subcutaneous, n = 8). All groups were treated for 8 weeks. The blood samples were analyzed by autoanalyzer and ELISA kits for biochemical and endocrinological parameters, respectively.

Results

Glucose, HbA1c, triglyceride, low density cholesterol (LDL), leptin, and Homeostatic Model Assessment for insulin resistance (HOMA-IR) levels increased and insulin and HOMA-β levels decreased in the diabetic rats compared to the healthy control group. The glucose, HbA1c, and triglyceride levels were partially decreased; however, insulin and HOMA-β levels were increased by low-dose albendazole therapy. The high dose of lansoprazole treatment increased insulin level.

Conclusion

The lansoprazole and albendazole treatments can be a potential drug or combined with antidiabetic drugs in T2D treatment by Adenosine 5′-monophosphate activated protein kinase (AMPK), peroxisome proliferator-activated receptor (PPAR), incretin-like effect and other antidiabetic mechanisms. It may be beneficial to create an effective treatment strategy by developing more specific substances with benzimidazole scaffold.

An updated review on therapeutic potential and recent advances in drug delivery of Berberine: Current status and future prospect

Natural products are well known for their high potency with minimum side effects. Plant extracts are the most commonly used natural products because of their ease of availability and relatively low production cost. Berberine (BBR), a phytochemical component of some Chinese medicinal herbs (most commonlyBerberis vulgaris), is an isoquinoline alkaloid with several biological and pharmacological effects including antioxidant, anti-inflammatory, antitumour, antimicrobial, antidepressant,hepatoprotective, hypolipidemic, and hypoglycemic actions. Interestingly, multiple studies have shown that BBR is a potential drug candidate with a multi-spectrum therapeutic application. However, the oral delivery of BBR is challenged owing to its poor bioavailability. Therefore, its oral bioavailability needs to be enhanced before it can be used in many clinical applications. This review provides an overview of the various studies that support the broad range of pharmacological activities of BBR. Also, it includes a section to address the issues and challenges related with the drug and methods to improve the properties of BBR such as solubility, stability and bioavailability that may be explored to help patients reap the maximum benefit from this potentially useful drug.

AMPK: A bridge between diabetes mellitus and Alzheimer's disease

The pathogenesis and etiology of diabetes mellitus (DM) and Alzheimer's disease (AD) share many common cellular and molecular themes. Recently, a growing body of research has shown that AMP-activated protein kinase (AMPK), a biomolecule that regulates energy balance and glucose and lipid metabolism, plays key roles in DM and AD. In this review, we summarize the relevant research on the roles of AMPK in DM and AD, including its functions in gluconeogenesis and insulin resistance (IR) and its relationships with amyloid β-protein (Aβ), Tau and AMPK activators. In DM, AMPK is involved in the regulation of glucose metabolism and IR. AMPK is closely related to gluconeogenesis, which can not only be activated by the upstream kinases liver kinase B1 (LKB1), transforming growth factor β-activated kinase 1 (TAK1), and Ca²⁺/calmodulin-dependent protein kinase kinase β (CaMKKβ) but also regulate the downstream kinases glucose-6-phosphatase (G-6-Pase) and phosphoenolpyruvate carboxy kinase (PEPCK), thereby affecting gluconeogenesis and ameliorating DM. Moreover, AMPK can regulate glucose transporter 4 (GLUT4) and free fatty acids to improve IR. In AD, AMPK can ameliorate abnormal brain energy metabolism, not only by reduces Aβ deposition through β-secretase but also reduces tau hyperphosphorylation through sirtuin 1 (SIRT1) and protein phosphatase 2A (PP2A). Therefore, AMPK is a bridge between DM and AD.

Determination of the antidiabetic chemical basis of Phellodendri Chinensis Cortex by integrating hepatic disposition in vivo and hepatic gluconeogenese inhibition in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Phellodendri Chinensis Cortex (PCC) has been an herb clinically used to treat diabetes, but the chemical basis of its antidiabetic effects has remained unclear.

AIM OF THIS STUDY

Based on the efficacy of herbal medicine resulting from the cooperative response of the effective compounds in the target organs with sufficient exposure, the in vivo hepatic disposition and in vitro hepatic gluconeogenesis inhibition were integrated to elucidate the chemical basis for the antidiabetic effect of orally administered PCC from a target organ, liver, perspective.

MATERIALS AND METHODS

With a developed and validated HPLC-MS/MS method, three alkaloids and five metabolites were determined in the portal vein plasma, liver, and systemic plasma of rats orally administered PCC. The inhibition of hepatic gluconeogenesis by the eight compounds was evaluated in primary hepatocytes.

RESULTS

The in vivo results showed that magnoflorine was present at the highest concentration among the target constituents in the plasma, where berberine showed a low concentration. In contrast, berberine showed the highest concentration in the liver, and its five metabolites exhibited substantial hepatic accumulation. This discrepancy was strongly associated with the hepatic disposition of the compounds. The hepatic disposition prevented the transfer of 96.1% of the phellodendrine, 71.1% of the berberine and 47.5% of the magnoflorine from the portal vein plasma to the systemic plasma, which corresponded to their hepatic distribution and hepatic metabolism. In vitro, berberine, M1, M4 and M5 significantly and dose-dependently inhibited hepatic glucose production. By integrating the hepatic exposure and inhibitory activity data, we estimated that berberine contributed the most (74%) to the total glucose production inhibition of the orally administered PCC decoction, followed by M4 (14%), M1 (11%) and M5 (1%).

CONCLUSION

This study was the first to comprehensively describe the pharmacokinetic profiles and hepatic disposition of alkaloids in PCC, and concluded that berberine and its metabolites contributed the most to the total hepatic gluconeogenesis inhibition by orally administered PCC. These results reveal the chemical basis for the antidiabetic effect of orally administered PCC decoction, providing scientific evidence to support the clinical usage of PCC in diabetes treatment.

Therapeutic effect of berberine on metabolic diseases: Both pharmacological data and clinical evidence

The increased incidence of metabolic diseases (e.g., diabetes and obesity) has seriously affected human health and life safety worldwide. It is of great significance to find effective drugs from natural compounds to treat metabolic diseases. Berberine (BBR), an important quaternary benzylisoquinoline alkaloid, exists in many traditional medicinal plants. In recent years, BBR has received widespread attention due to its good potential in the treatment of metabolic diseases. In order to promote the basic research and clinical application of BBR, this review provides a timely and comprehensive summary of the pharmacological and clinical advances of BBR in the treatment of five metabolic diseases, including type 2 diabetes mellitus, obesity, non-alcoholic fatty liver disease, hyperlipidemia, and gout. Both animal and clinical studies have proved that BBR has good therapeutic effects on these five metabolic diseases. The therapeutic effects of BBR are based on regulating various metabolic aspects and pathophysiological procedures. For example, it can promote insulin secretion, improve insulin resistance, inhibit lipogenesis, alleviate adipose tissue fibrosis, reduce hepatic steatosis, and improve gut microbiota disorders. Collectively, BBR may be a good and promising drug candidate for the treatment of metabolic diseases. More studies, especially clinical trials, are needed to further confirm its molecular mechanisms and targets. In addition, large-scale, long-term and multi-center clinical trials are necessary to evaluate the efficacy and safety of BBR in the treatment of these metabolic diseases.

The effect of Berberine on weight loss in order to prevent obesity: A systematic review

This study provides a critical overview of experimental studies in vitro, in humans, and in animals that evaluated the efficacy of Berberine and its effect on management of obesity and the related metabolic consequences. As a result of this review, we summarized the effects of Berberine in different models and the related mechanism of actions. In preclinical models, Berberine demonstrates that it affects gut microbiota by reducing diversity of microbes starting at a dosage of 100 mg/kg/day. Moreover, in animal models, Berberine explicates an action on glucose through the inhibition of α-glycosidase at a dose of 200 mh/kg/day. Berberine is also known to be effective against differentiation of adipocytes through a decrease in LXRs, PPARs, and SREBPs expression at 150 mg/kg/day. Other mechanism ascribed to Berberine are related to its inhibition of hepatic gluconeogenesis through the Phospheoenolpyruvate carboxykinase (PEPCK), Glucose-6-phosphate (G6Pase) and AMP-activated protein kinase (AMPK). Furthermore, Berberine (associated to Red Yeast Rice) is effective in decreasing lipid levels in rats, which consequently lowers the change of weight gain at dosage of 40 mg/kg to 380 mg/kg/day. All the above preclinical data are confirmed in human studies where Berberine can modulate the diversity of gut microbes at the dose of 500 mg/day. In addition, Berberine is found to have a beneficial impact on gene regulation for the absorption of cholesterol at a daily dose of 300 mg in humans, an amelioration on glucose accumulation at 1.0 g daily dose was also observed. For all these reasons, this review gives an important good account of the impact of Berberine in obesity treatment and prevention.

lncRNA-mRNA competing endogenous RNA network in IR-hepG2 cells ameliorated by APBBR decreasing ROS levels: a systematic analysis

Background

Radix Astragali (Astragalus membranaceus var. mongholicus (Bunge)) and Coptis chinensis (Coptis chinensis var. angustiloba) are two commonly prescribed traditional Chinese herbs for diabetes. Astragalus Polysaccharide (AP) and Berberine (BBR) are active ingredients of these two herbs respectively and they are scientifically proved to have immunomodulatory and anti-inflammatory effects. They are also known for their antidiabetic potential by ameliorating insulin resistance (IR). AP and BBR have shown different advantages in treating diabetes according to previous reports. However, very few studies focus on the combined activities of the two potential antidiabetic ingredients. In this study, we discovered that reactive oxygen species (ROS) accumulated in IR-hepG2 cells and APBBR can decrease ROS level in model group significantly. We conjectured that APBBR can ameliorate IR in hepG2 cells by decreasing ROS level. In order to verify this hypothesis, we obtained phenotype and transcriptome information of IR-HepG2 cells and explore the underlying mechanism of the combination of AP and BBR(APBBR) activity on the relationship between ROS change in IR at whole-transcriptome level, so as to shed new light to efficacy and application of APBBR in treating diabetes.

Methods

The IR cell model was established with high-level insulin intervention. Glucose content, HepG2 cell viability as well as ROS level was detected to study the effect of IR-hepG2 cell phenotype. Unbiased genome-wide RNA sequencing was used to investigate alterations in experimental groups. Then, GO and KEGG functional enrichment was performed to explore the function and pathway of target genes. Venn analysis found out the differentially expressed lncRNAs that had close relationship with IR and ROS. Finally, we screened out candidate lncRNAs and these target genes to construct interaction network of differentiated lncRNA–miRNA–mRNA by according to the principle of competitive endogenous RNA (ceRNA).

Results

The biochemical experiments showed that APBBR administration could improve the proliferation activity of IR-HepG2 cells and decrease ROS level in model cells. The GO and KEGG functional enrichment analyses demonstrated several mRNAs remarkably enriched in biological processes and signaling pathways related to ROS production and IR progression. Interaction network suggest that APBBR ameliorates IR in HepG2 cells by regulating the expression of multiple genes and activating relevant signaling pathway to decrease ROS level. Thus, we demonstrated that APBBR ameliorated IR in hepG2 cells via the ROS-dependent pathway.

Phytopharmacology and Clinical Updates of Berberis Species Against Diabetes and Other Metabolic Diseases

The incidences of diabetic mellitus and other metabolic diseases such as hypertension and hyperlipidemia are increasing worldwide; however, the current treatment is not able to control the rapidly increasing trend in diabetes mortality and morbidity. Studies related to the effectiveness of extracts and pure compounds obtained from plants have shown promising responses in preclinical and clinical studies related to these metabolic diseases. Plants belonging to the genus Berberis (Family: Berberidaceae) are widely distributed with nearly 550 species worldwide. Extracts and compounds obtained from Berberis species, especially Berberine alkaloid, showed effectiveness in the management of diabetes and other metabolic diseases. Various pharmacological experiments have been performed to evaluate the effects of Berberis extracts, berberine, and its natural and chemically synthesized derivatives against various cell and animal disease models with promising results. Various clinical trials conducted so far also showed preventive effects of Berberis extracts and berberine against metabolic diseases. The present review focuses on i) research updates on traditional uses, ii) phytopharmacology and clinical studies on Berberis species, and iii) active metabolites in the prevention and treatment of diabetes and other metabolic diseases with a detailed mechanism of action. Furthermore, the review critically analyzes current research gaps in the therapeutic use of Berberis species and berberine and provides future recommendations.

Berberine for prevention of dementia associated with diabetes and its comorbidities: A systematic review

BACKGROUND

A growing number of epidemiological studies indicate that metabolic syndrome (MetS) and its associated features play a key role in the development of certain degenerative brain disorders, including Alzheimer's disease and vascular dementia. Produced by several different medicinal plants, berberine is a bioactive alkaloid with a wide range of pharmacological effects, including antidiabetic effects. However, it is not clear whether berberine could prevent the development of dementia in association with diabetes.

OBJECTIVE

To give an overview of the therapeutic potential of berberine as a treatment for dementia associated with diabetes.

SEARCH STRATEGY

Database searches A and B were conducted using PubMed and ScienceDirect. In search A, studies on berberine's antidementia activities were identified using "berberine" and "dementia" as search terms. In search B, recent studies on berberine's effects on diabetes were surveyed using "berberine" and "diabetes" as search terms.

INCLUSION CRITERIA

Clinical and preclinical studies that investigated berberine's effects associated with MetS and cognitive dysfunction were included.

DATA EXTRACTION AND ANALYSIS

Data from studies were extracted by one author, and checked by a second; quality assessments were performed independently by two authors.

RESULTS

In search A, 61 articles were identified, and 22 original research articles were selected. In search B, 458 articles were identified, of which 101 were deemed relevant and selected. Three duplicates were removed, and a total of 120 articles were reviewed for this study. The results demonstrate that berberine exerts beneficial effects directly in the brain: enhancing cholinergic neurotransmission, improving cerebral blood flow, protecting neurons from inflammation, limiting hyperphosphorylation of tau and facilitating β-amyloid peptide clearance. In addition, evidence is growing that berberine is effective against diabetes and associated disorders, such as atherosclerosis, cardiomyopathy, hypertension, hepatic steatosis, diabetic nephropathy, gut dysbiosis, retinopathy and neuropathy, suggesting indirect benefits for the prevention of dementia.

CONCLUSION

Berberine could impede the development of dementia via multiple mechanisms: preventing brain damages and enhancing cognition directly in the brain, and indirectly through alleviating risk factors such as metabolic dysfunction, and cardiovascular, kidney and liver diseases. This study provided evidence to support the value of berberine in the prevention of dementia associated with MetS.

Interaction of Nuclear Receptor Subfamily 4 Group A Member 1 (Nr4a1) and Liver Linase B1 (LKB1) Mitigates Type 2 Diabetes Mellitus by Activating Monophosphate-Activated Protein Kinase (AMPK)/Sirtuin 1 (SIRT1) Axis and Inhibiting Nuclear Factor-kappa B (NF-κB) Activation

BACKGROUND Nuclear receptor subfamily 4 group A member 1 (Nr4a1) has been increasingly investigated in association with type 2 diabetes mellitus (T2DM). This study aimed to explore its efficacy with liver kinase B1 (LKB1) and potential signaling pathways in T2DM. MATERIAL AND METHODS A T2DM model in rats was established by high-fat diet and injection of 30 mg/kg streptozotocin. The ectopic expression of Nr4a1 or in combination with LKB1 was performed in T2DM rats to probe their effects on T2DM. Then, the weight and indicators of blood lipid and blood glucose in normal rats and T2DM rats were measured. The volume change of adipocytes and the size of lipid droplets in white adipose tissue (WAT) were observed by hematoxylin-eosin staining and oil red O staining, respectively. We also measured levels of Nr4a1, LKB1, and adenosine monophosphate-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/Nuclear factor-kappa B (NF-kappaB) axis-related proteins. RESULTS In T2DM rats, Nr4a1 was highly expressed, and body weight, blood lipid and blood glucose were increased, and the volume of adipocytes and the size of lipid droplets in WAT were increased, which were all reversed by low expression of Nr4a1. After treatment with Nr4a1 and LKB1 together, T2DM rats showed decreased levels of blood lipid, blood glucose, and reduced volume of adipocytes and lipid droplet size in WAT, with activated AMPK/SIRT1 signaling pathway and inhibited NF-kappaB. CONCLUSIONS Our results highlight that interaction of Nr4a1 and LKB1 can mitigate T2DM by activating the AMPK/SIRT1 signaling pathway and inhibiting NF-kappaB activation. This may offer new insight for T2DM treatment.

Berberine Attenuates Hyperglycemia by Inhibiting the Hepatic Glucagon Pathway in Diabetic Mice

Dysregulated glucagon drives hyperfunction in hepatic glucose output, which is the main cause of persistent hyperglycemia in type 2 diabetes. Berberine (Zhang et al., 2010) has been used as a hypoglycemic agent, yet the mechanism by which BBR inhibits hepatic gluconeogenesis remains incompletely understood. In this study, we treated diabetic mice with BBR, tested blood glucose levels, and then performed insulin, glucose lactate, and glucagon tolerance tests. Intracellular cAMP levels in hepatocytes were determined by ELISA, hepatic gluconeogenetic genes were assayed by RT-qPCR, and the phosphorylation of CREB, which is the transcriptional factor controlling the expression of gluconeogenetic genes, was detected by western blot. BBR reduced blood glucose levels, improved insulin and glucose tolerance, and suppressed lactate- and glucagon-induced hepatic gluconeogenesis in ob/ob and STZ-induced diabetic mice. Importantly, BBR blunted glucagon-induced glucose production and gluconeogenic gene expression in hepatocytes, presumably through reducing cAMP, which resulted in the phosphorylation of CREB. By utilizing a cAMP analogue, adenylate cyclase (AC), to activate cAMP synthetase, and an inhibitor of the cAMP degradative enzyme, phosphodiesterase (PDE), we revealed that BBR accelerates intracellular cAMP degradation. BBR reduces the intracellular cAMP level by activating PDE, thus blocking activation of downstream CREB and eventually downregulating gluconeogenic genes to restrain hepatic glucose production.

Effect of He Qi San on DNA Methylation in Type 2 Diabetes Mellitus Patients with Phlegm-blood Stasis Syndrome

This study was performed to elucidate the potential influence of He Qi San (HQS) on glucose and lipid metabolism in type 2 diabetes mellitus (T2DM) patients with phlegm-blood stasis syndrome (PBSS), and to determine DNA methylation changes. Sixty T2DM patients with PBSS were randomly divided into control and HQS groups. The control group received conventional treatments, and the HQS group received conventional treatments plus HQS. Glucose metabolism (FPG, 2hPG, FINS, and HbA1c) and lipid metabolism indexes (TG, TC and LDL-C) were determined. Genes with differential DNA methylation were subjected to GO and KEGG analyses. Glucose and lipid metabolism indexes in both groups were reduced, but were much more pronounced in the HQS group. Differential promoter CpG methylation regions were identified in 682 genes, including 426 genes with high-CpG promoters, 150 genes with intermediate CpG promoters, and 106 genes with low CpG promoters. Genes with differential DNA methylation were mainly enriched in the AMPK and insulin signaling pathways, terpenoid backbone biosynthesis, and renin secretion. We concluded that HQS remarkably improved indexes of glucose and lipid metabolism in T2DM patients with PBSS through regulating the DNA methylation of genes in the AMPK and insulin signaling pathways and terpenoid backbone biosynthesis.

Combined Use of Astragalus Polysaccharide and Berberine Attenuates Insulin Resistance in IR-HepG2 Cells via Regulation of the Gluconeogenesis Signaling Pathway

Insulin resistance (IR) is likely to induce metabolic syndrome and type 2 diabetes mellitus (T2DM). Gluconeogenesis (GNG) is a complex metabolic process that may result in glucose generation from certain non-carbohydrate substrates. Chinese herbal medicine astragalus polysaccharides and berberine have been documented to ameliorate IR, and combined use of astragalus polysaccharide (AP) and berberine (BBR) are reported to synergistically produce an even better effect. However, what change may occur in the GNG signaling pathway of IR-HepG2 cells in this synergistic effect and whether AP-BBR attenuates IR by regulating the GNG signaling pathway remain unclear. For the first time, we discovered in this study that the optimal time of IR-HepG2 cell model formation was 48 h after insulin intervention. AP-BBR attenuated IR in HepG2 cells and the optimal concentration was 10 mg. AP-BBR reduced the intracellular H₂O₂ content with no significant effect on apoptosis of IR-HepG2 cells. In addition, a rapid change was observed in intracellular calcium current of the IR-HepG2 cell model, and AP-BBR intervention attenuated this change markedly. The gene sequencing results showed that the GNG signaling pathway was one of the signaling pathways of AP-BBR to attenuate IR in IR-Hepg2 cells. The expression of p-FoxO1^Ser256 and PEPCK protein was increased, and the expression of GLUT2 protein was decreased significantly in the IR-HepG2 cell model, and both of these effects could be reversed by AP-BBR intervention. AP-BBR attenuated IR in IR-HepG2 cells, probably by regulating the GNG signaling Pathway.

Natural Alkaloids Intervening the Insulin Pathway: New Hopes for Anti-Diabetic Agents?

BACKGROUND

Accumulating experimental data supports the capacity of natural compounds to intervene in complicated molecular pathways underlying the pathogenesis of certain human morbidities. Among them, diabetes is now a world's epidemic associated with increased risk of death; thus, the detection of novel anti-diabetic agents and/or adjuvants is of vital importance. Alkaloids represent a diverse group of natural products with a range of therapeutic properties; during the last 20 years, published research on their anti-diabetic capacity has been tremendously increased.

PURPOSE

To discuss current concepts on the anti-diabetic impact of certain alkaloids, with special reference to their molecular targets throughout the insulin-signaling pathway.

METHODOLOGY

Upon in-depth search in the SCOPUS and PUBMED databases, the literature on alkaloids with insulin secretion/sensitization properties was critically reviewed.

RESULTS

In-vitro and in-vivo evidence supports the effect of berberine, trigonelline, piperine, oxymatrine, vindoneline, evodiamine and neferine on insulin-signaling and related cascades in beta-cells, myocytes, adipocytes, hepatocytes and other cells. Associated receptors, kinases, hormones and cytokines, are affected in terms of gene transcription, protein expression, activity and/or phosphorylation. Pathophysiological processes associated with insulin resistance, beta-cell failure, oxidative stress and inflammation, as well as clinical phenotype are also influenced.

DISCUSSION

Growing evidence suggests the ability of specific alkaloids to intervene in the insulin-signal transduction pathway, reverse molecular defects resulting in insulin resistance and glucose intolerance and improve disease complications, in-vitro and in-vivo. Future indepth molecular studies are expected to elucidate their exact mechanism of action, while large clinical trials are urgently needed to assess their potential as anti-diabetic agents.

Small molecule IVQ, as a prodrug of gluconeogenesis inhibitor QVO, efficiently ameliorates glucose homeostasis in type 2 diabetic mice

Gluconeogenesis is a major source of hyperglycemia in patients with type 2 diabetes mellitus (T2DM), thus targeting gluconeogenesis to suppress glucose production is a promising strategy for anti-T2DM drug discovery. In our preliminary in vitro studies, we found that a small-molecule (E)-3-(2-(quinoline-4-yl)vinyl)-1H-indol-6-ol (QVO) inhibited the hepatic glucose production (HGP) in primary hepatocytes. We further revealed that QVO suppressed hepatic gluconeogenesis involving calmodulin-dependent protein kinase kinase β- and liver kinase B1-adenosine monophosphate-activated protein kinase (AMPK) pathways as well as AMPK-independent mitochondrial function-related signaling pathway. To evaluate QVO's anti-T2DM activity in vivo, which was impeded by the complicated synthesis route of QVO with a low yield, we designed and synthesized 4-[2-(1H-indol-3-yl)vinyl]quinoline (IVQ) as a prodrug with easier synthesis route and higher yield. IVQ did not inhibit the HGP in primary hepatocytes in vitro. Pharmacokinetic studies demonstrated that IVQ was quickly converted to QVO in mice and rats following administration. In both db/db and ob/ob mice, oral administration of IVQ hydrochloride (IVQ-HCl) (23 and 46 mg/kg every day, for 5 weeks) ameliorated hyperglycemia, and suppressed hepatic gluconeogenesis and activated AMPK signaling pathway in the liver tissues. Furthermore, IVQ caused neither cardiovascular system dysfunction nor genotoxicity. The good druggability of IVQ has highlighted its potential in the treatment of T2DM and the prodrug design for anti-T2DM drug development.

Rhizoma coptidis as a Potential Treatment Agent for Type 2 Diabetes Mellitus and the Underlying Mechanisms: A Review

Diabetes mellitus, especially type 2 diabetes mellitus (T2DM), has become a significant public health burden. Rhizoma coptidis (RC), known as Huang Lian, is widely used for treating diabetes in China. The bioactive compounds of RC, especially alkaloids, have the potential to suppress T2DM-induced lesions, including diabetic vascular dysfunction, diabetic heart disease, diabetic hyperlipidemia, diabetic nephropathy, diabetic encephalopathy, diabetic osteopathy, diabetic enteropathy, and diabetic retinopathy. This review summarizes the effects of RC and its bioactive compounds on T2DM and T2DM complications. Less research has been conducted on non-alkaloid fractions of RC, which may exert synergistic action with alkaloids. Moreover, we summarized the pharmacokinetic properties and structure-activity relationships of RC on T2DM with reference to extant literature and showed clearly that RC has potential therapeutic effect on T2DM.

Adenovirus-mediated expression of SIK1 improves hepatic glucose and lipid metabolism in type 2 diabetes mellitus rats

Aim

In this study, we investigated the role and mechanism of Salt-induced kinase 1 (SIK1) in regulation of hepatic glucose and lipid metabolism in a high-fat food (HFD) and streptozocin (STZ)-induced type 2 diabetes mellitus (T2DM) rat model.

Methods

A diabetic rat model treated with HFD plus low-dose STZ was developed and was transduced to induce a high expression of SIK1 in vivo via a tail-vein injection of a recombinant adenoviral vector. The effects on hepatic glucogenetic and lipogenic gene expression, systemic metabolism and pathological changes were then determined.

Results

In T2DM rats, SIK1 expression was reduced in the liver. Overexpression of SIK1 improved hyperglycaemia, hyperlipidaemia and fatty liver, reduced the expression of cAMP-response element binding protein (CREB)-regulated transcription co-activator 2 (CRTC2), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase), pS577 SIK1, sterol regulatory element binding-protein-1c (SREBP-1c) and its target genes, including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), and increased the expression of SIK1, pT182 SIK1 and pS171 CRTC2 in diabetic rat livers with the suppression of gluconeogenesis and lipid deposition.

Conclusion

SIK1 plays a crucial role in the regulation of glucose and lipid metabolism in the livers of HFD/STZ-induced T2DM rats, where it suppresses hepatic gluconeogenesis and lipogenesis by regulating the SIK1/CRTC2 and SIK1/SREBP-1c signalling pathways. Strategies to activate SIK1 kinase in liver would likely have beneficial effects in patients with T2DM and nonalcoholic fatty liver disease (NAFLD).

Effects of berberine on blood glucose in patients with type 2 diabetes mellitus: a systematic literature review and a meta-analysis

We conducted a systematic review and meta-analysis to evaluate the effect of Berberine on glucose in patients with type 2 diabetes mellitus and identify potential factors may modifying the hypoglycemic effect. We searched PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure, and Wanfang Database to identify randomized controlled trials that investigated the effect of Berberine. We calculated weighted mean differences (WMD) and 95% confidence interval (CI) for fasting plasma glucose (FPG), postprandial plasma glucose (PPG) and glycated haemoglobin (HbA1c) levels. Twenty-eight studies were identified for analysis, with a total of 2,313 type 2 diabetes mellitus (T2DM) patients. The pool data showed that Berberine treatment was associated with a better reduction on FPG (WMD = -0.54 mmol/L, 95% CI: -0.77 to -0.30), PPG (WMD = -0.94 mmol/L, 95% CI: -1.27 to -0.61), and HbA1c (WMD = -0.54 mmol/L, 95% CI: -0.93 to -0.15) than control groups. Subgroup-analyses indicated that effects of Berberine on blood glucose became unremarkable as the treatment lasted more than 90 days, the daily dosage more than 2 g/d and patients aged more than 60 years. The efficiency of Berberine combined with hypoglycaemics is better than either Berberine or hypoglycaemic alone. The dosage and treatment duration of Berberine and patients' age may modify the effect.

AMPK activation is involved in hypoglycemic and hypolipidemic activities of mogroside-rich extract from Siraitia grosvenorii (Swingle) fruits on high-fat diet/streptozotocin-induced diabetic mice

AMPK is involved in hypoglycemic and hypolipidemic activities of mogrosides from Siraitia grosvenorii (Swingle) fruits on diabetic mice.

Curcumin restrains hepatic glucose production by blocking cAMP/PKA signaling and reducing acetyl CoA accumulation in high-fat diet (HFD)-fed mice

OBJECTIVE

This study is designed to investigate whether curcumin reduces excessive hepatic glucose production (HGP) via regulation of second messenger cAMP.

METHODS

High-fat diet (HFD)-fed mice were orally administrated of metformin (200 mg/kg) or curcumin (50 mg/kg) daily for 10 weeks. Meanwhile, we stimulated mouse primary hepatocytes with palmitate (PA).

RESULTS

Curcumin reduced hepatic cAMP accumulation by preserving PDE4B induction, thereby suppressing gluconeogenesis via blocking cAMP/PKA activation. Curcumin reduced lipid deposition by reducing free fatty acid uptake and prevented acetyl CoA accumulation by combating mitochondrial oxidation. As a result from inhibiting acetyl CoA accumulation, curcumin protected pyruvate dehydrogenase (PDH) activity and inhibited pyruvate carboxylase (PC), limiting the shift of mitochondrial pyruvate from oxidation to gluconeogenesis via the carboxylation.

CONCLUSION

Curcumin reduced cAMP accumulation by preserving PDE4B activity and inhibited acetyl CoA production by reducing mitochondrial fatty acid oxidation, thereby restraining pyruvate-driven hepatic glucose production.

Berberine Reduces Pyruvate-driven Hepatic Glucose Production by Limiting Mitochondrial Import of Pyruvate through Mitochondrial Pyruvate Carrier 1

BACKGROUND

Mitochondrial pyruvate import via mitochondrial pyruvate carrier (MPC) is a central step in hepatic gluconeogenesis. Berberine inhibits hepatic gluconeogenesis, but the mechanism is incompletely understood. This study aims to investigate whether berberine could reduce excessive hepatic glucose production (HGP) by limiting mitochondrial import of pyruvate through MPC1.

METHODS

High-fat diet (HFD) feeding augmented HGP. The effects of berberine on hepatic fatty acid oxidation, sirtuin3 (SIRT3) induction and mitochondrial pyruvate carrier 1 (MPC1) function were examined.

FINDINGS

HFD feeding increased hepatic acetyl coenzyme A (acetyl CoA) accumulation with impaired pyruvate dehydrogenase (PDH) activity and increased pyruvate carboxylase (PC) induction. Berberine reduced acetyl CoA accumulation by limiting fatty acid oxidation and prevented mitochondrial pyruvate shift from oxidation to gluconeogenesis through carboxylation. Upon pyruvate response, SIRT3 binded to MPC1 and stabilized MPC1 protein via deacetylation modification, facilitating mitochondrial import of pyruvate. Berberine preserved the acetylation of MPC1 by suppression of SIRT3 induction and impaired MPC1 protein stabilization via protein degradation, resultantly limiting mitochondrial pyruvate supply for gluconeogenesis.

INTERPRETATION

Berberine reduced acetyl CoA contents by limiting fatty acid oxidation and increased MPC1 degradation via preserving acetylation, thereby restraining HGP by blocking mitochondrial import of pyruvate. These findings suggest that limitation of mitochondrial pyruvate import might be a therapeutic strategy to prevent excessive hepatic glucose production.

The Pathogenesis of Diabetes Mellitus by Oxidative Stress and Inflammation: Its Inhibition by Berberine

A substantial knowledge on the pathogenesis of diabetes mellitus (DM) by oxidative stress and inflammation is available. Berberine is a biologically active botanical that can combat oxidative stress and inflammation and thus ameliorate DM, especially type 2 DM. This article describes the potential of berberine against oxidative stress and inflammation with special emphasis on its mechanistic aspects. In diabetic animal studies, the modified levels of proinflammatory cytokines and oxidative stress markers were observed after administering berberine. In renal, fat, hepatic, pancreatic and several others tissues, berberine-mediated suppression of oxidative stress and inflammation was noted. Berberine acted against oxidative stress and inflammation through a very complex mechanism consisting of several kinases and signaling pathways involving various factors, including NF-κB (nuclear factor-κB) and AMPK (AMP-activated protein kinases). Moreover, MAPKs (mitogen-activated protein kinases) and Nrf2 (nuclear factor erythroid-2 related factor 2) also have mechanistic involvement in oxidative stress and inflammation. In spite of above advancements, the mechanistic aspects of the inhibitory role of berberine against oxidative stress and inflammation in diabetes mellitus still necessitate additional molecular studies. These studies will be useful to examine the new prospects of natural moieties against DM.

The Signaling Pathways Involved in the Antiatherosclerotic Effects Produced by Chinese Herbal Medicines

Cardiovascular diseases (CVDs) are considered to be the predominant cause of death in the world. Chinese herb medicines (CHMs) have been widely used for the treatment of CVDs in Asian countries for thousands of years. One reason of high efficacy of CHMs in treating CVDs is attributed to their inhibition in atherosclerosis (AS) development, a critical contributor to CVDs occurrence. Cumulative studies have demonstrated that CHMs alleviate atherogenesis via mediating pathophysiologic events involved in AS. However, there is deficiency in the summaries regarding antiatherogenic signal pathways regulated by CHMs. In this review, we focus on the signal cascades by which herb medicines and relevant extractives, derivatives, and patents improve proatherogenic processes including endothelium dysfunction, lipid accumulation, and inflammation. We mainly elaborate the CHMs-mediated signaling pathways in endothelial cells, macrophages, and vascular smooth muscle cells of each pathogenic event. Moreover, we briefly describe the other AS-related factors such as thrombosis, autophagy, immune response, and noncoding RNAs and effects of CHMs on them in the way of cascade regulation, which is helpful to further illustrate the molecular mechanisms of AS initiation and progression and discover newly effective agents for AS management.

Cellular stress response mechanisms of Rhizoma coptidis: a systematic review

Rhizoma coptidis has been used in China for thousands of years with the functions of heating dampness and purging fire detoxification. But the underlying molecular mechanisms of Rhizoma coptidis are still far from being fully elucidated. Alkaloids, especially berberine, coptisine and palmatine, are responsible for multiple pharmacological effects of Rhizoma coptidis. In this review, we studied on the effects and molecular mechanisms of Rhizoma coptidis on NF-κB/MAPK/PI3K–Akt/AMPK/ERS and oxidative stress pathways. Then we summarized the mechanisms of these alkaloid components of Rhizoma coptidis on cardiovascular and cerebrovascular diseases, diabetes and diabetic complications. Evidence presented in this review implicated that Rhizoma coptidis exerted beneficial effects on various diseases by regulation of NF-κB/MAPK/PI3K–Akt/AMPK/ERS and oxidative stress pathways, which support the clinical application of Rhizoma coptidis and offer references for future researches.

Natural products, an important resource for discovery of multitarget drugs and functional food for regulation of hepatic glucose metabolism

Imbalanced hepatic glucose homeostasis is one of the critical pathologic events in the development of metabolic syndromes (MSs). Therefore, regulation of imbalanced hepatic glucose homeostasis is important in drug development for MS treatment. In this review, we discuss the major targets that regulate hepatic glucose homeostasis in human physiologic and pathophysiologic processes, involving hepatic glucose uptake, glycolysis and glycogen synthesis, and summarize their changes in MSs. Recent literature suggests the necessity of multitarget drugs in the management of MS disorder for regulation of imbalanced glucose homeostasis in both experimental models and MS patients. Here, we highlight the potential bioactive compounds from natural products with medicinal or health care values, and focus on polypharmacologic and multitarget natural products with effects on various signaling pathways in hepatic glucose metabolism. This review shows the advantage and feasibility of discovering multicompound-multitarget drugs from natural products, and providing a new perspective of ways on drug and functional food development for MSs.

Barberry in the treatment of obesity and metabolic syndrome: possible mechanisms of action

Obesity is a consequence of an imbalance between energy intake and energy expenditure. It affects people of both genders and all age groups, ethnicity and socioeconomic groups, and in developed and developing countries. Obesity is often accompanied by the metabolic syndrome (MetS). MetS is characterized by a clustering of cardiovascular risk factors, including high blood pressure, adiposity, dyslipidemia and glucose intolerance, which together increase the risk of atherosclerotic cardiovascular disease, type 2 diabetes mellitus and other causes of mortality. Nowadays, there is a growing interest in the use of plant-based agents instead of synthetic drugs to manage chronic diseases such as MetS; one such example is Berberis vulgaris. B. vulgaris contains isoquinonline alkaloids such as berberine, berberrubine and berbamine. Recent studies have proved that berberine exhibits pharmacological activities and positive effects on the risk factors of obesity and MetS. We have reviewed original articles related to the possible molecular mechanisms of action of berberine on obesity and MetS. Berberine suppresses adipocyte differentiation and decreases obesity. It also regulates glucose metabolism via decreasing insulin resistance and increasing insulin secretion. Other effects of berberine include antihyperlipidemic and antihypertensive activities and endothelial protection.

Effects of type 2 diabetes mellitus on the pharmacokinetics of berberine in rats

CONTEXT

Berberine is an active alkaloid isolated from Rhizoma coptidis [Coptis chinensis Franch. (Ranunculaceae)] that is widely used for the treatment of diabetes, hyperlipidemia and hypertension. However, the pharmacokinetics of berberine in normal rats and type 2 diabetes mellitus (T2DM) model rats are not clear.

OBJECTIVE

This study compares the pharmacokinetics of berberine between normal and T2DM model rats.

MATERIALS AND METHODS

The T2DM model rats were fed with high fat diet for 4 weeks, induced by low-dose (30 mg/kg) streptozotocin for 72 h and validated by determining the peripheral blood glucose level. Rats were orally treated with berberine at a dose of 20 mg/kg and then berberine concentration in rat plasma was determined by employing a sensitive and rapid LC-MS/MS method.

RESULTS

The significantly different pharmacokinetic behaviour of berberine was observed between normal and T2DM model rats. When compared with the normal group, C_max, t_1/2 and AUC_(0-t) of berberine were significantly increased in the model group (17.35 ± 3.24 vs 34.41 ± 4.25 μg/L; 3.95 ± 1.27 vs 9.29 ± 2.75 h; 151.21 ± 23.96 vs 283.81 ± 53.92 μg/h/L, respectively). In addition, oral clearance of berberine was significantly decreased in the model group (134.73 ± 32.15 vs 62.55 ± 16.34 L/h/kg).

DISCUSSION AND CONCLUSION

In T2DM model rats, the pharmacokinetic behaviour of berberine was significantly altered, which indicated that berberine dosage should be modified in T2DM patients.