Berberine stimulates glucose transport through a mechanism distinct from insulin

Efficacy evaluation of Berberis aristata and Silybum marianum fixed dose combination on glycaemic and insulin resistance parameters in adult population: a systematic review and meta-analysis of randomized controlled trials

Background

Diabetes is one of the most prevalent metabolic diseases with high rate of morbidity and mortality. The increased level of blood glucose level and increased insulin resistance is the hallmark of diabetes. Currently, various non-pharmacological and pharmacological therapeutic options are used for lowering the glucose level and improving the insulin activity. The current systematic review and meta-analysis study was conducted to evaluate the efficacy of Berberis aristata and Silybum marianum fixed dose nutraceutical combination on serum glucose and glycated haemoglobin level and insulin resistance parameters.

Main Body

Randomized controlled trials, identified from three online databases, evaluating the efficacy of Berberis aristata and Silybum marianum fixed dose combination were identified and evaluated as per pre-defined protocol. Quality of studies was evaluated using PEDro scale, and risk of bias was assessed using Cochrane Risk of Bias Tool. Pooled effect was reported as mean difference (MD) and 95% confidence interval, while the complete study was conducted as per PRISMA and Cochrane guidelines. After complete literature screening and evaluation process, seven studies were included in the final analysis. Data of 825 participants (active group: 416 participants and control group: 409 participants) were utilized for the statistical analysis. All included studies (except one) were of good quality. Supplementation of fixed dose combination significantly reduced glucose level (MD: − 5.26 mg/dl; p = 0.02) and glycated haemoglobin (HbA1c) level (MD: − 0.69%; p < 0.0001) as compared to control therapy, while greater insulin resistance reduction was observed in active group and the difference approached significance (MD: − 0.64 HOMA-IR score; p = 0.08). Risk of bias analysis revealed some concerns regarding biasness (mainly due to randomization, outcome measurement and selected reporting biasness). All included studies had moderate risk of biasness. Sensitivity analysis revealed effect of particular study on overall heterogeneity observed, while neither significant publication bias nor any missing study was observed.

Conclusion

The results of current study suggest that B. aristata and S. marianum fixed dose combination is effective in improving glycaemic and insulin parameters and can be effective in diabetic population. The observed sensitivity of certain studies on overall heterogeneity and the moderate risk of biasness warrants further well-designed clinical studies to strengthen the results of current study.

Berberine: Pharmacological Features in Health, Disease and Aging

BACKGROUND

Berberine is the main active compound of different herbs and is defined as an isoquinoline quaternary botanical alkaloid found in barks and roots of numerous plants. It exhibits a wide range of pharmacological effects, such as anti-obesity and antidiabetic effects. Berberine has antibacterial activity against a variety of microbiota, including many bacterial species, protozoa, plasmodia, fungi, and trypanosomes.

OBJECTIVE

This review describes the role of berberine and its metabolic effects. It also discusses how it plays a role in glucose metabolism, fat metabolism, weight loss, how it modulates the gut microbiota, and what are its antimicrobial properties along with its potential side effects with maximal tolerable dosage.

METHODS

Representative studies were considered and analyzed from different scientific databases, including PubMed and Web of Science, for the years 1982-2022.

RESULTS

Literature analysis shows that berberine affects many biochemical and pharmacological pathways that theoretically yield a positive effect on health and disease. Berberine exhibits neuroprotective properties in various neurodegenerative and neuropsychological ailments. Despite its low bioavailability after oral administration, berberine is a promising tool for several disorders. A possible hypothesis would be the modulation of the gut microbiome. While the evidence concerning the aging process in humans is more limited, preliminary studies have shown positive effects in several models.

CONCLUSION

Berberine could serve as a potential candidate for the treatment of several diseases. Previous literature has provided a basis for scientists to establish clinical trials in humans. However, for obesity, the evidence appears to be sufficient for hands-on use.

Addressing the preventive and therapeutic perspective of berberine against diabetes

Diabetes has emerged as one the leading detrimental factors for human life expectancy worldwide. The disease is mainly considered as outcome of dysregulation in glucose metabolism, resulting in consistent high glucose concentration in blood. At initial stages, the diabetes particularly type 2 diabetes, is manageable by lifestyle interventions such as regular physical activity and diet with less carbohydrates. However, in advance stage, regular intake of external insulin dose and medicines like metformin are recommended. The long-term consumption of metformin is associated with several side effects such as nausea, vomiting, diarrhoea, lectic acidosis etc., In this scenario, several plant-based medicines have shown promising potential for the prevention and treatment of diabetes. Berberine is the bioactive compound present in the different plant parts of berberis family. Biochemical studies have shown that berberine improve insulin sensitivity and insulin secretion. Additionally, berberine induces glucose metabolism by activating AMPK signaling and inhibition of inflammation. A series of studies have demonstrated the antidiabetic potential of berberine at in vitro, pre-clinical and clinical trials. This review provides comprehensive details of preventive and therapeutic potential of berberine against diabetes.

Overall and Sex-Specific Effect of Berberine on Glycemic and Insulin-Related Traits: a Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Berberine is widely available as a nutraceutical supplement for improving glucose metabolism. Berberine affects sex hormones, raising the possibility that its effects on glycemic traits and insulin sensitivity have sex disparity which has been overlooked.

OBJECTIVE

To assess the overall and sex-specific effects of berberine on glycemic- and insulin-related traits.

METHODS

We identified randomized trials of berberine versus placebo from Medline, Embase, CNKI, clinical trial registries and previous systematic reviews. Mean differences were estimated using inverse-variance weighting with random effects models. Subgroup analyses were conducted by sex, diabetes diagnosis, trial duration, berberine dose and ethnicity.

RESULTS

We identified 20 eligible studies (n = 1761). Berberine lowered fasting glucose (-0.52 mmol/L, 95% CI -0.72 to -0.33; 18 studies, n = 1522), HbA1c (-4.48 mmol/mol, 95% CI -6.53 to -2.44, 7 studies, n = 756), fasting insulin (-2.36 mU/L, 95% CI -3.64 to -1.08, 11 studies, n = 966), HOMA-IR (-0.85, 95% CI -1.16 to -0.53,12 studies, n = 1065), and 2-h postprandial glucose (-1.81 mmol/L, 95% CI -2.37 to -1.24, 4 studies, n = 501). Effects on fasting glucose and HOMA-IR showed potential differences by sex, with larger reductions in women than in men. Comparing 4 studies conducted in women to one study conducted in men, the mean difference was -0.21 mmol/L (95% CI -0.41 to -0.00) for fasting glucose and -0.97 (95% CI -1.84 to -0.10) for HOMA-IR. We also found larger reductions in fasting glucose in participants with diabetes and in Asians.

CONCLUSION

Berberine is effective in improving glucose metabolism and may result in larger effects on fasting glucose in women, in people with diabetes and in Asians, but subgroup comparisons remain to be replicated given the limited number of studies. Berberine can be considered as a complementary intervention in individuals who may benefit from modest improvements in glucose metabolism and who prefer taking a nutraceutical.

STUDY REGISTRATION

PROSPERO (CRD42022345172).

Efficacy and safety of HIMABERB® Berberine on glycemic control in patients with prediabetes: double-blind, placebo-controlled, and randomized pilot trial

BACKGROUND

Prediabetes and diabetes involve alterations in glucose homeostasis, including increased fasting blood glucose and impaired glucose tolerance. Berberine has been identified as a potential regulator of glucose homeostasis with implications on the management of type 2 diabetes mellitus (DM). Given a paucity of data on berberine in prediabetes, evaluation of its effect in individuals with prediabetes may prove clinically valuable.

OBJECTIVE

The present pilot study aimed to investigate the effect of daily oral berberine on markers of glycemic control and insulin resistance among individuals with prediabetes.

METHODS

A randomized, double-blinded, placebo-controlled trial was conducted for 12 weeks among 34 individuals with prediabetes as defined by the American Diabetes Association (fasting plasma glucose (FPG) between 5.6 and 6.9 mmol/L, glycosylated hemoglobin (HbA1c) between 5.7% and 6.4%, or 2-hour 75-gram oral glucose tolerance test (2 h-OGTT) between 7.8 and 11.1 mmol/L). HIMABERB® 500 mg was given three times daily to the treatment group, and placebo was administered three times daily to the control group. Glycemic control markers and physical parameters were evaluated for both groups on days 0, 28, 56, and 84. The glycemic control markers assessed included FPG, fasting insulin (FI), 2 h-OGTT, HbA1c, and homeostatic model assessment-insulin resistance (HOMA-IR). The observed outcomes were analyzed using independent t-test statistics to determine the significance of differences over time after treatment initiation and between treatment and control groups.

RESULTS

Significant decreases in all markers of glycemic control were observed in the treatment group at intermediate time points and the endpoint of the study compared to baseline levels and to the control group. For the treatment group, FPG decreased from 6.75 ± 0.23 mmol/L to 5.33 ± 0.28 mmol/L, FI from 9.81 ± 0.36 to 7.88 ± 0.52 mmol/L, 2 h-OGTT from 10.44 ± 0.52 to 8.12 ± 0.40 mmol/L, HbA1c from 6.40% ± 0.20-5.43% ± 0.21%, and HOMA-IR from 3.61 ± 0.31 to 2.41 ± 0.14. The decreases in glycemic control markers compared to the control group were clinically and statistically significant (p<10- 5). No severe adverse effects, kidney or liver toxicity were detected.

CONCLUSION

After 12 weeks, berberine (HIMABERB®) intervention in individuals with prediabetes significantly reduced glycemic control markers, with mean FPG and 2 h-OTGG being reduced to below prediabetic thresholds, supporting the investigation of the use of HIMABERB® for delaying progression to diabetes mellitus.

TRIAL REGISTRATION

http://ctri.nic.in (CTRI/2021/12/038751) (20/12/2021).

Berberine suppressed sarcopenia insulin resistance through SIRT1-mediated mitophagy

Abnormal mitochondrial function resulting in inadequate energy supply leads to sarcopenia and IR, suggesting that maintaining mitochondrial homeostasis by regulating mitophagy may be a promising strategy for sarcopenia IR therapy. Herein, we constructed sarcopenia mice model, which was treated with berberine and/or SIRT1/mitophagy inhibitors, and the activity of SIRT1/mitophagy signaling pathway was identified. Then, muscle tissue, blood biochemical index, inflammatory factors, GTT, and ITT were detected. We found that berberine treatment increased the body weight and alleviated d-galactose-induced weight loss in mice. SIRT1/mitophagy inhibitors suppressed the effects of berberine in the treatment of sarcopenia. The effect of berberine on the increase of muscle tissue, improving metabolic disorders, reducing the expression of inflammatory factors, and suppressing sarcopenia insulin resistance (IR) were reversed by SIRT1/mitophagy inhibitors. Our study establishes proof-of-concept to distinct the effect of berberine in sarcopenia IR, and provides strong evidence to support the hypothesis that berberine-induced SIRT1 triggers mitochondrial autophagy pathway and suppresses IR in sarcopenia.

Vindoline Exhibits Anti-Diabetic Potential in Insulin-Resistant 3T3-L1 Adipocytes and L6 Skeletal Myoblasts

Type 2 diabetes mellitus (T2DM) emerged as a major health care concern in modern society, primarily due to lifestyle changes and dietary habits. Obesity-induced insulin resistance is considered as the major pathogenic factor in T2DM. In this study, we investigated the effect of vindoline, an indole alkaloid of Catharanthus roseus on insulin resistance (IR), oxidative stress and inflammatory responses in dexamethasone (IR inducer)-induced dysfunctional 3T3-L1 adipocytes and high-glucose-induced insulin-resistant L6-myoblast cells. Results showed that dexamethasone-induced dysfunctional 3T3-L1 adipocytes treated with different concentrations of vindoline significantly enhanced basal glucose consumption, accompanied by increased expression of GLUT-4, IRS-1 and adiponectin. Similarly, vindoline-treated insulin-resistant L6 myoblasts exhibited significantly enhanced glycogen content accompanied with upregulation of IRS-1 and GLUT-4. Thus, in vitro studies of vindoline in insulin resistant skeleton muscle and dysfunctional adipocytes confirmed that vindoline treatment significantly mitigated insulin resistance in myotubes and improved functional status of adipocytes. These results demonstrated that vindoline has the potential to be used as a therapeutic agent to ameliorate obesity-induced T2DM-associated insulin resistance profile in adipocytes and skeletal muscles.

A Descriptive Review of the Action Mechanisms of Berberine, Quercetin and Silymarin on Insulin Resistance/Hyperinsulinemia and Cardiovascular Prevention

Insulin resistance (IR) and the associated hyperinsulinemia are early pathophysiological changes which, if not well treated, can lead to type 2 diabetes, endothelial dysfunction and cardiovascular disease. While diabetes care is fairly well standardized, the prevention and treatment of IR lacks a single pharmaceutical approach and many lifestyle and dietary interventions have been proposed, including a wide range of food supplements. Among the most interesting and well-known natural remedies, alkaloid berberine and the flavonol quercetin have particular relevance in the literature, while silymarin-the active principle of the Silybum marianum thistle-was traditionally used for lipid metabolism disorders and to sustain liver function. This review describes the major defects of insulin signaling leading to IR and the main properties of the three mentioned natural substances, their molecular targets and synergistic action mechanisms. The actions of berberine, quercetin and silymarin are partially superimposable as remedies against reactive oxygen intermediates generated by a high-lipid diet and by NADPH oxidase, which is triggered by phagocyte activation. Furthermore, these compounds inhibit the secretion of a battery of pro-inflammatory cytokines, modulate intestinal microbiota and are especially able to control the various disorders of the insulin receptor and post-receptor signaling systems. Although most of the evidence on the effects of berberine, quercetin and silymarin in modulating insulin resistance and preventing cardiovascular disease derive from experimental studies on animals, the amount of pre-clinical knowledge strongly suggests the need to investigate the therapeutic potential of these substances in human pathology.

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.

Can Berberine Serve as a New Therapy for Parkinson's Disease?

Parkinson's disease (PD) is a neurodegenerative disorder characterized by dopaminergic neurodegeneration and deposition of alpha-synuclein. Mechanisms associated with PD etiology include oxidative stress, apoptosis, autophagy, and abnormalities in neurotransmission, to name a few. Drugs used to treat PD have shown significant limitations in their efficacy. Therefore, recent focus has been placed on the potential of active plant ingredients as alternative, complementary, and efficient treatments. Berberine is an isoquinoline alkaloid that has shown promise as a pharmacological treatment in PD, given its ability to modulate several molecular pathway associated with the disease. Here, we review contemporary knowledge supporting the need to further characterize berberine as a potential treatment for PD.

Berberine Modulates Macrophage Activation by Inducing Glycolysis

Classical activation of macrophage and monocyte differentiation induced by β-glucan is accompanied with metabolic change in glucose. However, the role of the metabolic rewiring in monocyte/macrophage activation remains elusive. In this study, we show that berberine induces aerobic glycolysis by blocking the tricarboxylic acid cycle and modulates cytokine responses in bone marrow-derived macrophages (BMDMs) from mice and human PBMC. 13-Methyberberine had activities on glucose metabolism and BMDM activation similar to those of berberine, whereas other tested derivatives lost both activities. Glucose transporter (GLUT)1 expression and total cellular hexokinase activity increased gradually in BMDMs in the presence of berberine. In the contrast, LPS upregulated GLUT1 and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) levels in 6 h. Extracellular glucose levels and replacing glucose with galactose in culture medium affected the cytokine secretion of BMDMs. Berberine alleviated enteritis of Salmonella typhimurium infection and protected mice against endotoxic shock. In mice i.p. injected with LPS, the increase of serum TNF-α and the drop of blood glucose were attenuated by berberine treatment. These data together demonstrated that macrophage activation was closely related with glucose metabolism.

Evaluation on Antidiabetic Properties of Medicinal Plants from Myanmar

Objectives

To explore the effective and safe medicines for treating diabetes.

Methods

Hydroalcoholic extracts of 130 medicinal plants belonging to 66 families were evaluated using porcine pancreatic lipase (PPL) inhibition and glucose uptake methods together with a literature review.

Results

The extracts of 22 species showed the PPL inhibition activity; 18 extracts of 15 species stimulated glucose uptake in 3T3-L1 adipocytes. Among them, Mansonia gagei J.R. Drumm., Mesua ferrea L., and Centella asiatica (L.) Urb. exhibited both activities. The extracts of Caladium lindenii (André) Madison rhizomes and Azadirachta indica A. Juss. leaves presented the utmost lipase inhibitory activity with IC₅₀ of 6.86 ± 0.25 and 11.46 ± 0.06 μg/mL, respectively. The extracts of Coptis teeta Wall. rhizomes and Croton tiglium L. seeds stimulated the maximum glucose uptake. Ten species are reported to have antidiabetic activity for the first time. Flavonoids and triterpenoids are the dominant antidiabetic compounds in selected medicinal plants from Myanmar.

Conclusions

P. zeylanica, L. cubeba, H. crenulate, M. gagei, C. teeta, and M. ferrea are worthy to advance further study according to their strong antidiabetic activities and limited research on effects in in vivo animal studies, unclear chemical constitutes, and safety.

A patent review of berberine and its derivatives with various pharmacological activities (2016-2020)

INTRODUCTION

Berberine (BBR), as one of the outstanding representatives of isoquinoline alkaloids, has been used as an antibacterial drug for a long time in China since ancient times. Currently, a large number of studies have been reported that berberine has a wide spectrum of pharmacological activities, such as anti-tumor, anti-inflammatory, hypoglycemic, hypolipidemic, anti-obesity, and the like.

AREAS COVERED

This review systematically discussed important patents on berberine and berberine derivatives in terms of pharmacological activity between 2016 and 2020. These patents were mainly searched through the European Patent Office database and Web of Science. These berberine patents (~41) cover a wide range of applications, mainly including antitumor, anti-inflammatory, antibacterial, anti-metabolic disorder, and other newly reported pharmacological activities.

EXPERT OPINION

Berberine is an important lead compound with great potential for optimization in drug development. However, there is a lack of research related to the biomolecular targets of BBR, which directly restricts the development of berberine in the pharmaceutical field. The problems involved with poor bioavailability and cytotoxicity are also worth considering in the development of berberine-based drugs. Accordingly, the increasing number of patents involving biomolecular targets in BBR's patent applications will be published as its related pharmacological mechanisms are further deciphered.

Protocatechuic acid influences immune-metabolic changes in the adipose tissue of pregnant women with gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with immune metabolic changes that increase women's risk of developing metabolic disorders later in life. Nutritional intervention is a crucial component in reducing the burden of these pathological features. We examined whether protocatechuic acid (PCA), a major metabolite of anthocyanins abundant in plant food, is able to exert insulin-mimetic activity and modulate inflammation in the visceral adipose tissue (VAT) obtained at delivery, from pregnant women with GDM or normal glucose tolerance (NGT). PCA stimulated glucose uptake in the VAT from both GDM and NGT women. This capability was associated with increased phosphorylation of p38 mitogen-activated protein kinase (p38MAPK), as further demonstrated by the inhibitory effect of SB203580, a p38MAPK inhibitor, on PCA-induced glucose uptake. The GDM-VAT expressed lower adiponectin levels and PCA stimulated adiponectin release in the NGT-VAT and, albeit to a lower extent, in the GDM-VAT. Higher levels of IL6 and TNFα were secreted by the GDM-VAT compared with the NGT one, and PCA had no effects on them. PCA reduced the overexpression of vasoactive intestinal peptide receptor 2 (VPAC2) in the GDM-VAT. Further studies are needed to establish whether and how anthocyanins and food rich in these compounds may contribute to prevent or delay metabolic disorders in women with GDM.

A Citrullus colocynthis fruit extract acutely enhances insulin-induced GLUT4 translocation and glucose uptake in adipocytes by increasing PKB phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCE

Citrullus colocynthis (L.) Schrad is a common fruit in traditional medicine and used as remedy against various diseases, especially diabetes. Up to now, its anti-diabetic effects have been fully attributed to its enhancement of pancreatic insulin secretion. Whether C. colocynthis also ameliorates insulin action in peripheral tissues has not been investigated.

AIM OF THE STUDY

In the present study, using 3T3-L1 adipocytes as cell model, we have investigated whether colocynth fruit extracts affect insulin action.

MATERIALS AND METHODS

Various extracts were prepared from the C. colocynthis fruit and screened using a cell-based 96 well plate GLUT4 translocation assay. Promising extracts were further studied for their effects on glucose uptake and cell viability. The effect on insulin signal transduction was determined by Western blot and the molecular composition was established by LC-MS.

RESULTS

The ethyl acetate fractions of aqueous non-defatted extracts of seed and pulp, designated Sna1 and Pna1, acutely enhanced insulin-induced GLUT4 translocation. In accordance, both extracts increased insulin-stimulated cellular glucose uptake. Pna1, which displayed greater effects on GLUT4 and glucose uptake than Sna1, was further investigated and was demonstrated to increase GLUT4 translocation without changing the half-maximum dose (ED50) of insulin, nor changing GLUT4 translocation kinetics. At the molecular level, Pna1 was found to enhance insulin-induced PKB phosphorylation without changing phosphorylation of the insulin receptor. Pna1 appeared not to be toxic to cells and, like insulin, restored cell viability during serum starvation. By investigating the molecular composition of Pna1, nine compounds were identified that made up 87% of the mass of the extract, one of which is likely to be responsible for the insulin-enhancing effects of Pna1.

CONCLUSIONS

The C. colocynthis fruit possesses insulin-enhancing activity. This activity may explain in part its anti-diabetic effects in traditional medicine. It also identifies the C. colocynthis as a source of a potential novel insulin enhancer that may prove to be useful to reduce hyperglycemia in type 2 diabetes.

Modular and Divergent Syntheses of Protoberberine and Protonitidine Alkaloids

A modularly convergent and divergent strategy was established for the family synthesis of both protoberberine and protonitidine alkaloids. The robust, scalable, and flexible synthetic route featured a collective preparation of protoberberine and protonitidine alkaloids from a common isoquinoline assembled from pyridyne as the key synthon, which was based on the selective N-C or C-C cyclization via distinct processes. Through the strategy, 20 protoberberine alkaloids, 5 protonitidine alkaloids, and 11 analogues with diverse substituents were comprehensively aquired.

Adipose Tissue SIRT1 Regulates Insulin Sensitizing and Anti-Inflammatory Effects of Berberine

Berberine (BBR), which is an active component of Coptis chinensis Franch, has been reported to improve glucose metabolism and insulin resistance in animal and human studies, predominantly via activation of the 5′-adenosine monophosphate kinase (AMPK) pathway and suppression of the inflammation response. However, the mechanisms underlying the effects of BBR on AMPK and inflammation remain unclear. In this present study, we found that BBR upregulated SIRT1 expression in 3T3L-1 adipocytes and adipose tissue. Inhibition of SIRT1 blunted the BBR-induced increase in glucose consumption and uptake in adipocytes. The BBR-induced activation of the AMPK pathway and AKT phosphorylation in adipocytes and adipose tissue were also attenuated by inhibition or knockout of Sirt1. The BBR-induced improvement of systemic insulin sensitivity was impaired by Sirt1 knockout in HFD-induced obese mice. The suppressing effects of BBR on systemic and local inflammatory responses, such as serum concentrations and expression of inflammatory cytokines, phosphorylation of c-Jun N-terminal kinase (JNK) and IKKβ, and the accumulation of F4/80-positive macrophages in adipose tissue were also attenuated in Sirt1 knockout mice. The BBR-induced decrease in PGC-1α acetylation was reversed by inhibition or knockout of Sirt1 in adipocytes and adipose tissue. Together, these results indicate that adipose tissue SIRT1 is a key regulator of the insulin sensitizing and anti-inflammatory effects of BBR, which contributes to the improvement of metabolic dysregulation.

Berberine augments hypertrophy of colonic patches in mice with intraperitoneal bacterial infection

Colonic patches, the counterparts of Peyer's patches in the small intestine, are dynamically regulated lymphoid tissues in the colon that have an important role in defensing against microbial infections. Berberine is an isoquinoline alkaloid extracted from medicinal herbs including Rhizoma coptidis and has long been used for the treatment of infectious gastroenteritis, but its impact on the colonic lymphoid tissues (such as colonic patches) is unknown. In this study, we aimed to investigate whether berberine had any influences on the colonic patches in mice with bacterial infection. The results showed that oral berberine administration in bacterial infected mice substantially enhanced the hypertrophy of colonic patches, which usually possessed the features of two large B-cell follicles with a separate T-cell area. Moreover, the colonic patches displayed follicular dendritic cell networks within the B-cell follicles, indicative of mature colonic patches containing germinal centers. Concomitant with enlarged colonic patches, the cultured colon of infected mice treated with berberine secreted significantly higher levels of interleukin-1β (IL-1β), IL-6, TNF-α, and CCL-2, while NLRP3 inhibitor MMC950 or knockout of NLRP3 gene abrogated berberine-induced hypertrophy of colonic patches, suggesting the involvement of the NLRP3 signaling pathway in this process. Functionally, oral administration of berberine ameliorated liver inflammation and improved formed feces in the colon. Altogether, these results indicated that berberine was able to augment the hypertrophy of colonic patches in mice with bacterial infection probably through enhancing local inflammatory responses in the colon.

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.

Beta-Blockers and Berberine: A Possible Dual Approach to Contrast Neuroblastoma Growth and Progression

The use of nutraceuticals during cancer treatment is a long-lasting debate. Berberine (BBR) is an isoquinoline quaternary alkaloid extracted from a variety of medicinal plants. BBR has been shown to have therapeutic effects in different pathologies, particularly in cancer, where it affects pathways involved in tumor progression. In neuroblastoma, the most common extracranial childhood solid tumor, BBR, reduces tumor growth by regulating both stemness and differentiation features and by inducing apoptosis. At the same time, the inhibition of β-adrenergic signaling leads to a reduction in growth and increase of differentiation of neuroblastoma. In this review, we summarize the possible beneficial effects of BBR in counteracting tumor growth and progression in various types of cancer and, in particular, in neuroblastoma. However, BBR administration, besides its numerous beneficial effects, presents a few side effects due to inhibition of MAO A enzyme in neuroblastoma cells. Therefore, herein, we proposed a novel therapeutic strategy to overcome side effects of BBR administration consisting of concomitant administration of BBR together with β-blockers in neuroblastoma.

Dietary berberine regulates lipid metabolism in muscle and liver of black sea bream (Acanthopagrus schlegelii) fed normal or high-lipid diets

The present study investigated the influence of berberine (BBR) supplementation in normal and high-lipid (HL) diets on lipid metabolism and accumulation in black sea bream (Acanthopagrus schlegelii). BBR was supplemented at 50 mg/kg to control (Con, 11·1 % crude lipid) and high-lipid (HL, 20·2 % crude lipid) diets and named as ConB and HLB, respectively. After the 8-week feeding trial, fish body length and specific growth rate were significantly reduced by HL diets (P < 0·05). Muscle and whole-body crude lipid contents were significantly influenced by both BBR supplementation and dietary lipid level. Fish fed the HLB diet had significantly lower serum TAG, LDL-cholesterol contents and alanine aminotransferase activity compared with the HL group. The HL group presented vast lipid accumulation in the liver, and hypertrophied hepatocytes along with large lipid droplets, and translocation of nuclear to the cell periphery. These abnormalities in black sea bream were alleviated in the HLB group. BBR supplementation in the HL diet significantly down-regulated the hepatic expression levels of acetyl-CoA carboxylase α, sterol regulatory element-binding protein-1, 6-phosphogluconate dehydrogenase, glucose 6-phosphate dehydrogenase and pparγ, whereas the lipoprotein lipase, hormone-sensitive lipase and carnitine palmitoyltransferase 1a expression levels were significantly up-regulated. However, the expression levels of these genes showed opposite trends in muscle (except for pparγ). In conclusion, dietary BBR supplementation in the HL diet reduced hepatic lipid accumulation by down-regulating lipogenesis gene expression and up-regulating lipolysis gene expression, and it increased muscle lipid contents with opposite trends of the mechanism observed in the liver.

The effect of berberine supplementation on obesity indices: A dose- response meta-analysis and systematic review of randomized controlled trials

BACKGROUND

and purpose: Clinical studies investigating the effects of berberine supplementation on anthropometric indices in humans have generated inconsistent results. Thus, the objective of this systematic review and meta-analysis was to clarify the effects of berberine supplementation on obesity indices in human subjects.

METHODS

Several online medical databases were systematically searched up to February 2019. All clinical trials exploring the effects of berberine supplementation on indices of obesity were included. The combined weighted mean difference (WMD) of eligible studies was assessed using a random-effects model. We evaluated publication bias by using the Egger's test.

RESULTS

Overall, 10 studies were included. The combined outcomes suggested a significant influence of berberine administration on body mass index (BMI) (WMD: -0.29 kg/m², 95% CI: -0.51 to -0.08, p = 0.006) and waist circumference (WC) (WMD: -2.75 cm, 95% CI: -4.88 to -0.62, p = 0.01). However, berberine supplementation yielded no significant decline in body weight (BW) (WMD: -0.11 kg, 95% CI: -0.99 to 0.76, p = 0.79). Following the dose-response evaluation, berberine intake was found to significantly reduce BMI (r = -0.02) and WC (r = -0.72) based on treatment duration.

CONCLUSION

The results of the current study support the use of berberine supplementation for the improvement of obesity indices.

The Effect of Berberine on Reproduction and Metabolism in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Control Trials

Purpose

To assess the efficacy and safety of berberine on reproductive endocrine and metabolic outcomes in women with polycystic ovary syndrome (PCOS).

Methods

PubMed (from 1950), the Cochrane Library, the CNKI (from 1979), the VIP (from 1989), and the Wanfang Data (from 1990) and the reference lists of the retrieved articles were searched for randomized controlled trials in human beings with the search terms including "polycystic ovary syndrome/PCOS" and "berberine/BBR/Huangliansu (in Chinese)/Xiao bojian (in Chinese)" till 30 May 2019. Relevant indicators were collected and the data were analyzed by using RevMan 5.3 software.

Results

Eventually, a total of 12 randomized controlled trials were included in this systematic review. Our study suggested that berberine had similar live birth rates compared with placebo or metformin and lower live birth rates (RR: 0.61, 95% CI: 0.44 to 0.82) compared with letrozole. There was a significant difference between berberine and placebo and between berberine and no treatment in terms of decreasing total testosterone and luteinizing hormone to follicle-stimulating hormone (LH/FSH) ratio (8 RCTs, 577 participants, MD: -0.34, 95% CI: -0.47 to -0.20; 3 RCTs, 179 participants, MD: -0.44, 95% CI: -0.68 to -0.21, respectively). Berberine was associated with decreasing total cholesterol (3 RCTs, 201 participants; MD: -0.44, 95% CI: -0.60 to -0.29), waist circumference (3 RCTs, 197 participants, MD: -2.74, 95% CI: -4.55 to -0.93), and waist-to-hip ratio (4 RCTs, 258 participants, MD: -0.04, 95% CI: -0.05 to -0.03) compared with metformin, but not with improved BMI (4 RCTs, 262 participants, MD: -0.03, 95% CI: -0.46 to 0.39). Berberine did not increase the incidence of gastrointestinal adverse events (3 RCTs, 567 participants, RR: 1.01, 95% CI: 0.76 to 1.35) or serious events during pregnancy (RR: 0.98, 95% CI: 0.70 to 1.37) compared with placebo.

Conclusion

This review found no solid evidence that berberine could improve live birth or other clinical outcomes in women with PCOS. However, berberine appeared to be more efficacious for improving insulin resistance and dyslipidemia and decreasing androgen levels and LH/FSH ratio in women with PCOS when compared with metformin.

Effect of methyl tert-butyl ether on adipogenesis and glucose metabolism in vitro and in vivo

Methyl tert-butyl ether (MTBE), as a widely used gasoline additive, is suspected of being environmentally toxic. MTBE accumulates mainly in adipose tissue, but its effect on obesity or obesity-related metabolic disorders has not been well understood yet. Therefore, we examined the effect of MTBE on the adipose function and the related metabolic processes with both 3T3-L1 cell line and C57BL/6J mice model. We found that exposure to MTBE at the environmental relevant concentration (100 μmol/L) could significantly induce differentiation of preadipocyte and disturb insulin-stimulated glucose uptake of mature adipocyte. The in vivo observation in male mice showed a positive correlation of visceral white adipose tissue (vWAT) expansion and cell size increase with MTBE treatment in 14 weeks. Glucose tolerance and insulin sensitivity tests demonstrated that MTBE at 1000 μg/(kg·day) disturbed the systemic glucose metabolism in a gender-specific manner, which might be partly attributed to the alterations of gut microbiota community at genus level with respect to Akkermansia, Clostridium XlVb, and Megamonas. In summary, our study characterized the effect of MTBE on adipose tissue function and glucose homeostasis in vitro and in vivo, and revealed that systemic disorders of the glucose metabolism might be modulated by the related gut microbiota.

Amorphous solid dispersion of Berberine mitigates apoptosis via iPLA2β/Cardiolipin/Opa1 pathway in db/db mice and in Palmitate-treated MIN6 β-cells

Aims: Berberine (BBR) improves beta-cell function in Type 2 diabetes (T2D) because of its anti-apoptotic activity, and our laboratory developed a new preparation named Huang-Gui Solid Dispersion (HGSD) to improve the oral bioavailability of BBR. However, the mechanism by which BBR inhibits beta-cell apoptosis is unclear. We hypothesized that the Group VIA Ca²⁺-Independent Phospholipase A₂ (iPLA₂β)/Cardiolipin(CL)/Opa1 signaling pathway could exert a protective role in T2D by regulating beta-cell apoptosis and that HGSD could inhibit β-cell apoptosis through iPLA₂β/CL/Opa1 upregulation.

Methods: We examined how iPLA₂β and BBR regulated apoptosis and insulin secretion through CL/Opa1 in vivo and in vitro. In in vitro studies, we developed Palmitate(PA)-induced apoptotic cell death model in mouse insulinoma cells (MIN6). iPLA₂β overexpression and silencing technology were used to examine how the iPLA₂β/CL/Opa1 interaction may play an important role in BBR treatment. In in vivo studies, db/db mice were used as a diabetic animal model. The pancreatic islet function and morphology, beta-cell apoptosis and mitochondrial injury were examined to explore the effects of HGSD. The expression of iPLA₂β/CL/Opa1 was measured to explore whether the signaling pathway was damaged in T2D and was involved in HGSD treatment.

Results: The overexpression of iPLA₂β and BBR treatment significantly attenuated Palmitate- induced mitochondrial injury and apoptotic death compared with Palmitate-treated MIN6 cell. In addition, iPLA₂β silencing could simultaneously partly abolish the anti-apoptotic effect of BBR and decrease CL/Opa1 signaling in MIN6 cells. Moreover, HGSD treatment significantly decreased beta-cell apoptosis and resulted in the upregulation of iPLA₂β/CL/Opa1 compared to those of the db/db mice.

Conclusion: The results indicated that the regulation of iPLA₂β/CL/Opa1 by HGSD may prevent beta-cell apoptosis and may improve islet beta-cell function in Type 2 diabetic mice and in palmitate-treated MIN6 cells.

Berberine hydrochloride protects against cytokine-induced inflammation through multiple pathways in undifferentiated C2C12 myoblast cells

Obesity is associated with skeletal muscle insulin resistance and the development of metabolic syndrome. Undifferentiated skeletal muscle cells are sensitive to oxidative stress. Berberine hydrochloride (BBR) improves insulin resistance and exhibits anti-inflammatory properties. However, the underlying mechanism and the cell signaling pathways involved remain largely elusive. We therefore investigated the anti-inflammatory effects of BBR and the signaling pathways using skeletal C2C12 myoblast cells. Undifferentiated C2C12 myoblast cells were treated with interleukin-1β alone or in combination with tumor necrosis factor-α in the presence or absence of BBR. We found that BBR reduced the cytokine-induced expression of inducible nitric oxide synthase and stress-related kinases including p-38 mitogen-activated protein kinase, nuclear factor kappa B (NF-κB), and stress-activated protein kinases/Jun amino-terminal kinases (SAPK/JNK) in C2C12 myoblast cells. Furthermore, BBR reversed cytokine-mediated suppression of AMP-activated protein kinase (AMPKα), sirtuin-1 (SIRT-1), and PPAR-γ coactivator-1α (PGC-1α). In addition, cytokine-induced reduction of mitochondrial marker proteins and function were rescued after BBR treatment. Catalase, an antioxidant enzyme, was elevated after BBR treatment. Our results demonstrate that BBR ameliorates cytokine-induced inflammation. The anti-inflammatory effect of BBR in skeletal progenitor cells is mediated through pathways including activation of the AMPKα-SIRT-1-PGC-1α, inhibition of the mitogen-activated protein kinase 4 (MKK4)-SAPK/JNK-C-JUN, as well as protection of mitochondrial bioenergetics. BBR may be a potential medication for metabolic syndrome.

Utility of alkaloids as chemical and biomarkers for quality, efficacy, and safety assessment of botanical ingredients

BACKGROUND

Selecting the appropriate chemical and bio-markers for monitoring the quality, efficacy, and safety is critical for efficient and reliable assessment of traditional medicines derived from botanical sources. Chemical markers have been implicated primarily in establishing the analytical methodologies aiming at verification of the botanical sources of the raw materials, the extracts, and the finished products such as botanical dietary supplements and nutraceuticals. In addition, they have been employed in differentiation between crude or raw (unprocessed) and processed plant extracts, and identification as well as determination of potential toxicants and adulterants in herbal medicines. Additionally, these chemical markers are utilized for selection of efficient methods for extraction of plants. Further, biomarkers have been exploited in determination of the pharmacokinetic properties of bioactive herbal constituents. Alkaloids, unlike other plant constituents, are uniquely characterized by having basic properties, and possessing substantial and diverse pharmacological effects. These features make alkaloids attractive components for functioning as chemical and biomarkers in determining the quality of botanical ingredients where this class of phytochemicals prevail or is responsible for lending biological effects.

PURPOSE

The aim of the review is to exhibit the function of alkaloids as biomarkers and chemical markers in the evaluation of quality, efficacy, and safety of medicinal herbs and their commercial products.

METHODS

Literature acquisition was accomplished using the most commonly accessed scholarly search engines including SciFinder, PubMed, and Google Scholar. Secondly, the full-texts which are relevant to the topic were included in this review. This was followed by a thorough and detailed analysis of the collected information.

RESULTS

The literature search with main emphasis on the roles of alkaloids in the evaluation of quality, efficacy and safety of herbal medicines was evaluated to provide all succinct information in one place. Compilation of such critical information is expected to help the reader to appreciate alkaloids as important markers in the quality control of herbal drugs and products.

CONCLUSION

The current review article covers the fundamental roles played by alkaloids as chemical and biomarkers in assessing the essential parameters of the quality of botanical ingredients, as briefly described earlier. The utilization of alkaloids as biomarkers to determine the efficacy-linked pharmacokinetic parameters is limited to reviewing studies on human subjects.

Apolipoprotein A-I enhances insulin-dependent and insulin-independent glucose uptake by skeletal muscle

Therapeutic interventions that increase plasma high density lipoprotein (HDL) and apolipoprotein (apo) A-I levels have been reported to reduce plasma glucose levels and attenuate insulin resistance. The present study asks if this is a direct effect of increased glucose uptake by skeletal muscle. Incubation of primary human skeletal muscle cells (HSKMCs) with apoA-I increased insulin-dependent and insulin–independent glucose uptake in a time- and concentration-dependent manner. The increased glucose uptake was accompanied by enhanced phosphorylation of the insulin receptor (IR), insulin receptor substrate-1 (IRS-1), the serine/threonine kinase Akt and Akt substrate of 160 kDa (AS160). Cell surface levels of the glucose transporter type 4, GLUT4, were also increased. The apoA-I-mediated increase in glucose uptake by HSKMCs was dependent on phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt, the ATP binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-B1). Taken together, these results establish that apoA-I increases glucose disposal in skeletal muscle by activating the IR/IRS-1/PI3K/Akt/AS160 signal transduction pathway. The findings suggest that therapeutic agents that increase apoA-I levels may improve glycemic control in people with type 2 diabetes.

Polyherbal dietary supplementation for prediabetic adults: study protocol for a randomized controlled trial

Background

Prediabetes describes a state of hyperglycemia outside of normal limits that does not meet the criteria for diabetes diagnosis, is generally symptomless, and affects an estimated 38% of adults in the United States. Prediabetes typically precedes the diagnosis of type 2 diabetes, which accounts for increased morbidity and mortality. Although the use of dietary and herbal supplements is popular worldwide, and a variety of single herbal medicines have been examined for glycemic management, the potential of increasingly common polyherbal formulations to return glycemic parameters to normal ranges among adults with prediabetes remains largely unexplored. The purpose of this study is to evaluate the efficacy of a commercially available, polyherbal dietary supplement on glycemic and lipid parameters in prediabetic individuals.

Methods

In this multi-site, double-blinded, randomized controlled clinical trial, 40 participants with prediabetes will be randomized to either a daily oral polyherbal dietary supplement (GlucoSupreme™ Herbal; Designs for Health®, Suffield, CT, USA; containing cinnamon bark (Cinnamomum cassia), banaba leaf (Lagerstroemia speciosa standardized to 1% corosolic acid), kudzu root (Pueraria lobata standardized to 40% isoflavones), fenugreek seed (Trigonella foenum-graceum standardized to 60% saponins), gymnema leaf (Gymnema sylvestre standardized to 25% gymnemic acid), American ginseng root (Panax quinquefolius standardized to 5% ginsenosides), and berberine HCl derived from bark (Berberis aristata)) or placebo for 12 weeks. Short-, medium-, and comparatively long-term markers of glycemic control (blood glucose and fasting insulin, fructosamine, and glycated hemoglobin/A1c, respectively), and other glycemic parameters (GlycoMark, β-cell function, and insulin sensitivity/resistance) will be obtained. Lipid profile (total cholesterol, LDL, HDL, and triglycerides), inflammation (hs-CRP), progression to type 2 diabetes mellitus, as well as safety indices (ALT, AST) will be obtained. An intention-to-treat analysis will be used to assess changes in study outcomes.

Discussion

Treatment options for adults with prediabetes are currently limited. This study aims to evaluate the safety and efficacy of a commercially available dietary supplement in the popular, but as yet insufficiently studied, category of polyherbal formulas for the management of glycemic parameters and other biomarkers associated with prediabetes.

Trial registration

ClinicalTrials.gov, ID: NCT03388762. Retrospectively registered on 4 January 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3032-6) contains supplementary material, which is available to authorized users.

A Review of Antiplatelet Activity of Traditional Medicinal Herbs on Integrative Medicine Studies

Thrombotic events mainly occurred by platelet activation and aggregation. The vascular occlusion causes serious disease states such as unstable angina, ischemic stroke, and heart attack. Due to the pervading of thrombotic diseases, new antiplatelet drugs are necessary for preventing and treating arterial thrombosis without adverse side effects. Traditional medicinal herbs have been used for the treatment of human ailments for a long time. The clinically useful and safe products from traditional medicinal herbs were identified and developed in numerous pharmacological approaches. A complementary system of traditional medicinal herbs is a good candidate for pharmacotherapy. However, it still has a limitation in its function and efficacy. Thus, it is necessary to study the mode of action of traditional medicinal herbs as alternative therapeutic agents. In this review, we focused on our current understanding of the regulatory mechanisms of traditional medicinal herbs in antiplatelet activity and antithrombotic effect of traditional medicinal herbs on platelet function.

Berberine promotes glucose uptake and inhibits gluconeogenesis by inhibiting deacetylase SIRT3

OBJECTIVE

Many studies have confirmed the glucose-lowering effect of berberine in type 2 diabetes patients. Although the mechanism of action of berberine involves the improvement of insulin sensitivity, its hypoglycemic mechanism remains elusive. Here we show a new mechanism by which berberine antagonizes glucagon signaling and find that SIRT3 is involved in the hypoglycemic effect of berberine.

METHODS

Gene knockout and overexpression were used to assess the inhibitory effect of berberine on SIRT3. Downstream signaling pathways and the hypoglycemic effect of SIRT3 were evaluated by immunoblotting and metabolic monitoring.

RESULTS

We found that berberine led to mitochondrial dysfunction and AMP accumulation by inhibiting deacetylase SIRT3. We confirmed that AMP accumulation activated the AMPK signaling pathway and further promoted glucose uptake. Simultaneously, AMP accumulation reduced cyclic AMP (cAMP) levels and abrogated the phosphorylation of critical protein targets of protein kinase A (PKA). Furthermore, we found that phosphoenolpyruvate carboxykinase 1 (PEPCK1) is a key gluconeogenesis enzyme that can be stabilized by glucagon. Berberine caused significant PEPCK1 ubiquitination and degradation by antagonizing glucagon and was accompanied by high levels of PEPCK1 acetylation. Interestingly, berberine-induced glucagon inhibition is independent of AMPK activation. The in vivo data from sirt3 knockout mice were further confirmed by the in vitro experiments.

CONCLUSIONS

Berberine promotes glucose uptake and inhibits gluconeogenesis by inhibiting SIRT3, and regulating mitochondria-related pathways may provide a novel approach to the development of antidiabetic drugs.

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.

Rhinacanthins-rich Extract Enhances Glucose Uptake and Inhibits Adipogenesis in 3T3-L1 Adipocytes and L6 Myotubes

Background:

Obesity is one of the imperative dynamics in the incidence and intensification of type 2 diabetes mellitus (T2DM). Rhinacanthus nasutus leaf extracts are previously reported for their antidiabetic and antiobesity potential.

Objective:

The present study was performed to evaluate glucose uptake stimulatory and antiadipogenic activities of a standardized rhinacanthins-rich extract (RRE) and its marker compounds namely rhinacanthin-C (RC), rhinacanthin-D (RD), and rhinacanthin-N (RN) in 3T3-L1 and L6 cells.

Materials and Methods:

RRE was prepared by a green extraction process, and the marker compounds (RC, RD, and RN) were isolated from the RRE using a silica gel column chromatography. Glucose uptake stimulation in both 3T3-L1 and L6 cells was performed by quantification of residual glucose in the media using glucose oxidase kit. Antiadipogenic activity in 3T3-L1 adipocytes was performed by intracellular lipids quantification using oil red O dye.

Results:

At the highest effective dose, RRE (20 μg/mL) exhibited satisfactory glucose uptake stimulatory effect in 3T3-L1 adipocytes that equivalent to RN (20 μg/mL) and the positive control insulin (0.58 μg/mL) but higher than RC (20 μg/mL) and RD (20 μg/mL). In addition, treatments of L6 myotubes showed that RRE (2.5 μg/mL) exhibited potent and equivalent glucose uptake stimulation (>80%) to RC (2.5 μg/mL) and the standard drugs, insulin (2.90 μg/mL) and metformin (219.5 μg/mL), but higher than RD (2.5 μg/mL) and RN (2.5 μg/mL). Furthermore, RRE (20 μg/mL) exhibited potent antiadipogenic effect in 3T3-L1 adipocytes, which equivalent to RC (20 μg/mL) but higher than RD (20 μg/mL) and RN (20 μg/mL).

Conclusions:

The undertaken study suggests that RRE could be used as an effective remedy in the treatment of obesity-associated T2DM.

SUMMARY

Rhinacanthins-rich extract and its marker compounds showed potent glucose uptake stimulatory activity in 3T3-L1 adipocytes and L6 myotubes

Rhinacanthins-rich extract and rhinacanthin-C showed comparable antiadipogenic effect in 3T3-L1 adipocytes

RRE could be used as an effective remedy in the treatment of obesity-associated T2DM.

Abbreviations used: T2DM: Type-2 diabetes mellitus; RRE: Rhinacanthins-rich extract; RC: Rhinacanthin-C; RD: Rhinacanthin-D; RN: Rhinacanthin-N; α-MEM: α-Minimum essential medium; DMEM: Dulbecco's modified Eagle's medium; HS: Horse serum; FBS: Fetal bovine serum; BSA: Bovine serum albumin; IBMX: 3-isobutyl-1-methylxanthine; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; GO: Glucose oxidase; NMR: Nuclear magnetic resonance; HPLC: High-performance liquid chromatography.

Effectiveness and safety of bifidobacteria and berberine in people with hyperglycemia: study protocol for a randomized controlled trial

Background

Berberine is one of the most important examples of a Chinese traditional medicine that has hypoglycemic effects but there have been no randomized controlled trials of the drug in a larger sample. In addition, the use of probiotic biotherapy to maintain an appropriate intestinal flora may represent an effective early intervention for hyperglycemia. Unfortunately, there has been a shortage of relevant research on this possibility at the population level. This study was designed to determine the hypoglycemic effect and safety of both bifidobacteria and berberine administration to newly diagnosed patients with pre-diabetes or diabetes mellitus.

Methods/design

This is a multicenter, double-blind, randomized, and parallel-controlled study that includes a run-in period of 2 weeks and a treatment period of 16 weeks, which will be conducted between June 2015 and October 2018. The 300 randomized patients will be assigned to the following four groups for 16 weeks’ treatment: Bifidobacterium, berberine, Bifidobacterium combined berberine, and placebo control groups. The primary outcome is the absolute value of fasting plasma glucose compared with baseline after 16 weeks of treatment.

Discussion

This is the first randomized controlled trial to determine the hypoglycemic effect and safety of both bifidobacteria and berberine administration to newly diagnosed patients with pre-diabetes or diabetes mellitus. It may provide support for the use of berberine and bifidobacteria in the treatment of diabetes.

Trial registration

ClinicalTrials.gov, ID: NCT03330184. Retrospectively registered on 18 October 2017.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-018-2438-5) contains supplementary material, which is available to authorized users.

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.

Dihydrosanguinarine Enhances Glucose Uptake in Mouse 3T3-L1 Cells

Recently, more studies have aimed at identifying selective peroxisome proliferator-activated receptor gamma (PPARγ) modulators that transactivate the expression of PPARγ-dependent genes as partial agonists to improve diabetic symptoms with fewer side effects compared to classic PPARγ agonists such as thiazolidinediones. We found that dihydrosanguinarine (DHS) treatment induced preadipocyte differentiation and lipid droplet accumulation in 3T3-L1 cells, but this effect is weaker than that elicited by the full PPARγ agonist troglitazone. Furthermore, this effect was reduced by the addition of a PPARγ antagonist, indicating the involvement of PPARγ signaling. Our results suggest that the stimulatory effects of DHS on adipocyte differentiation and insulin sensitivity are mediated by suppressing adenosine monophosphate-activated protein kinase (AMPK) alpha, upregulating the expression of PPARγ and its target genes (particularly Glut-4 and adiponectin) and reducing PPARγ phosphorylation. DHS significantly enhanced the glucose uptake in 3T3-L1 adipocytes without observable cytotoxicity at the effective concentration (5 μM) applied.

Pear pomace ethanol extract improves insulin resistance through enhancement of insulin signaling pathway without lipid accumulation

BACKGROUND/OBJECTIVES

The anti-diabetic activity of pear through inhibition of α-glucosidase has been demonstrated. However, little has been reported about the effect of pear on insulin signaling pathway in obesity. The aims of this study are to establish pear pomace 50% ethanol extract (PPE)-induced improvement of insulin sensitivity and characterize its action mechanism in 3T3-L1 cells and high-fat diet (HFD)-fed C57BL/6 mice.

MATERIALS/METHODS

Lipid accumulation, monocyte chemoattractant protein-1 (MCP-1) secretion and glucose uptake were measure in 3T3-L1 cells. Mice were fed HFD (60% kcal from fat) and orally ingested PPE once daily for 8 weeks and body weight, homeostasis model assessment of insulin resistance (HOMA-IR), and serum lipids were measured. The expression of proteins involved in insulin signaling pathway was evaluated by western blot assay in 3T3-L1 cells and adipose tissue of mice.

RESULTS

In 3T3-L1 cells, without affecting cell viability and lipid accumulation, PPE inhibited MCP-1 secretion, improved glucose uptake, and increased protein expression of phosphorylated insulin receptor substrate 1 [p-IRS-1, (Tyr⁶³²)], p-Akt, and glucose transporter type 4 (GLUT4). Additionally, in HFD-fed mice, PPE reduced body weight, HOMA-IR, and serum lipids including triglyceride and LDL-cholesterol. Furthermore, in adipose tissue, PPE up-regulated GLUT4 expression and expression ratio of p-IRS-1 (Tyr⁶³²)/IRS, whereas, down-regulated p-IRS-1 (Ser³⁰⁷)/IRS.

CONCLUSIONS

Our results collectively show that PPE improves glucose uptake in 3T3-L1 cells and insulin sensitivity in mice fed a HFD through stimulation of the insulin signaling pathway. Furthermore, PPE-induced improvement of insulin sensitivity was not accompanied with lipid accumulation.

Jiangtang Xiaozhi Recipe () prevents diabetic retinopathy in streptozotocin-induced diabetic rats

OBJECTIVE

To evaluate the prevention effect of diabetic retinopathy of Jiangtang Xiaozhi Recipe (, JXR) in streptozotocin (STZ)-induced diabetic rats.

METHODS

Sprague-Dawley rats were randomly divided into normal control group and diabetic group. Rats in the diabetic group were induced by intraperitoneal administration of STZ (50 mg/kg), and subdivided into 5 groups. Rats in the diabetic control group were given saline; four treatment groups were given metformin (300 mg/kg), JXR (2, 4 and 8 g/kg) respectively for 8 weeks, while rats in the normal control group were injected with citrate buffer and given the same volume of vehicle. Body weight and food intake were measured every week. The hypoglycaemic effects were determined by testing fasting blood glucose (FBG) every other week, and hemoglobin A1c (HbA1c), insulin, and glucagon at the end of the treatment. The preventive effects of JXR on STZ-induced diabetic rats were determined by histopathological examination with hematoxylin and eosin staining, and periodic acid-schiff staining. The effects were further evaluated by serum superoxide dismutase (SOD) activity and malondialdehyde (MDA).

RESULTS

High-dose JXR significantly reduced FBG and HbA1c level at the 8th week of administration (P<0.01, P<0.05). JXR significantly increased insulin level (P<0.05), and decreased glucagon level (P<0.05). JXR showed the antioxidant defense with increased SOD activity and decreased MDA contents in diabetic rats. Histopathological studies revealed that there were no basement membrane thickening and mild destruction in the treated groups. Morphometric measurements of retina microvascular showed that acellular capillary and capillary density decreased in treated rats while pericyte and endothelial cell increasing after the treatment.

CONCLUSION

JXR have protective effect of diabetic retinopathy and its mechanism may be associated with the obvious hypoglycemic and antioxidant effect.

Two New Oleanane-type Triterpenoids from Methanolyzed Saponins of Momordica cochinchinensis

Two new oleanane-type triterpenoid saponins (1 and 2) were isolated from the methanolyzed total saponins of the seeds of Momordica cochinchinensis (Lour.) Spreng, together with 16 known compounds (3—18). Their structures were elucidated on the basis of detailed spectroscopic, including ID and 2D NMR, mass spectrometric, methanolysis and LC-MS analysis. All the isolates were tested for their cytotoxic activities against five human cancer cell lines (HL-60, SMMC-7721, PANC-1, A-549, and SW-480) and the glucose uptake activity. The known compound 6 exhibited toxic effects against HL-60 with an IC50 value of 18.1 μM, while 10 showed cytotoxicity against SMMC-7721 and A-549 cell lines, with IC50 values of 34.4 and 32.8 μM, respectively. In addition, the new compound 2 showed glucose uptake activity with a glucose consumption value of 0.29 μM at 10 μM concentration.

Berberine prevents progression from hepatic steatosis to steatohepatitis and fibrosis by reducing endoplasmic reticulum stress

The histological spectrum of nonalcoholic fatty liver diseases (NAFLD) ranges from hepatic steatosis to steatohepatitis and fibrosis. Berberine (BBR) is known for its therapeutic effect on obesity, hyperglycaemia and dyslipidaemia; however, its effect on NAFLD has yet to be thoroughly explored. Db/db mice and methionine-choline-deficient diet-fed mice were administered BBR via gavage. We found that BBR-treated mice were more resistant to steatosis in the liver than vehicle-treated mice and that BBR significantly reduced hepatic inflammation, fibrosis and lipid peroxides. The beneficial effect of BBR was associated with suppressing endoplasmic reticulum (ER) stress. Additionally, BBR decreased the free fatty acid-induced lipid accumulation and tunicamycin-induced ER stress in primary hepatocytes and hepatocyte cell lines. We demonstrated that BBR exhibited chaperone activity, reduced protein aggregation in vitro and alleviated tunicamycin-induced triglyceride and collagen deposition in vivo. Finally, we showed that BBR could reverse ER stress-activated lipogenesis through the ATF6/SREBP-1c pathway in vitro. These results indicated that BBR may be a new therapeutic strategy against hepatic steatosis and non-alcoholic steatohepatitis.