Targeting metabolic syndrome: candidate natural agents

Natural products for managing metabolic syndrome: a scoping review

Introduction

Metabolic syndrome comprises a collection of metabolic disorders stemming from factors like genetic predisposition, inadequate nutrition, stress, decreased physical activity, aging, and ethnicity. Although traditional pharmaceutical treatments exist for metabolic syndrome, their limited popularity is attributed to high costs and adverse effects. Consequently, natural products with fewer side effects have been explored for managing this condition. This literature review aims to explore the role of natural products including herbs, botanicals, vitamins, minerals, probiotics, and dietary supplements in managing metabolic syndrome.

Methods

This scoping review was conducted in five steps, involving the formulation of a research question, the retrieval and extraction of relevant studies, the selection of pertinent studies, the organization of information into tables, and the reporting of results. Data was collected from various databases including Embase, Science Direct, PubMed, Google Scholar, Scopus, and Web of Science, with a focus on studies published from 2010 to the present, available in English and with full-text accessibility.

Results

We identified 1,259 articles, screened their titles, abstracts, and full texts, ultimately incorporating 169 pertinent articles into this review (comprising 90 review articles, 32 trial articles, 6 in vitro articles, 38 in vivo articles, 1 experimental article and 2 observational articles). The study's outcomes revealed that natural products, encompassing plants and their derivatives, vitamins and supplements, as well as probiotics, can exert a beneficial influence on metabolic syndrome by regulating blood sugar, blood pressure, lipid profiles, obesity, and abnormal cholesterol and triglyceride levels.

Conclusion

The current study underscores the significance of natural products in addressing metabolic syndrome. Consequently, it is advisable to conduct further extensive research to assess the efficacy of these products, potentially integrating them into treatment regimens for individuals with metabolic syndrome.

Natural products for managing metabolic syndrome: a scoping review

Introduction

Metabolic syndrome comprises a collection of metabolic disorders stemming from factors like genetic predisposition, inadequate nutrition, stress, decreased physical activity, aging, and ethnicity. Although traditional pharmaceutical treatments exist for metabolic syndrome, their limited popularity is attributed to high costs and adverse effects. Consequently, natural products with fewer side effects have been explored for managing this condition. This literature review aims to explore the role of natural products including herbs, botanicals, vitamins, minerals, probiotics, and dietary supplements in managing metabolic syndrome.

Methods

This scoping review was conducted in five steps, involving the formulation of a research question, the retrieval and extraction of relevant studies, the selection of pertinent studies, the organization of information into tables, and the reporting of results. Data was collected from various databases including Embase, Science Direct, PubMed, Google Scholar, Scopus, and Web of Science, with a focus on studies published from 2010 to the present, available in English and with full-text accessibility.

Results

We identified 1,259 articles, screened their titles, abstracts, and full texts, ultimately incorporating 169 pertinent articles into this review (comprising 90 review articles, 32 trial articles, 6 in vitro articles, 38 in vivo articles, 1 experimental article and 2 observational articles). The study’s outcomes revealed that natural products, encompassing plants and their derivatives, vitamins and supplements, as well as probiotics, can exert a beneficial influence on metabolic syndrome by regulating blood sugar, blood pressure, lipid profiles, obesity, and abnormal cholesterol and triglyceride levels.

Conclusion

The current study underscores the significance of natural products in addressing metabolic syndrome. Consequently, it is advisable to conduct further extensive research to assess the efficacy of these products, potentially integrating them into treatment regimens for individuals with metabolic syndrome.

Effectiveness of anthocyanins rich foods on cardiometabolic factors in individuals with metabolic syndrome: a systematic review and meta-analysis

PURPOSE

The aim of this systematic review with meta-analysis was to determine whether anthocyanin-rich foods are effective to improve cardiometabolic markers in individuals with metabolic syndrome (MetS), compared with placebo or control interventions.

METHODS

We searched MEDLINE, CENTRAL, Embase, LILACS, CINAHL, and Web of Science from their inception up to March 2022. We include clinical trials (randomized clinical trials, controlled clinical trials, and cross-over trials) with anthocyanin-rich foods versus placebo or control intervention that assessment cardiometabolic factors.

RESULTS

We found 14 clinical trials that met the eligibility criteria, and we included 10 studies for the quantitative synthesis. For anthocyanin-rich foods versus control interventions, the mean difference (MD) for low-density lipoprotein (LDL) was - 7.98 mg/dL (CI = - 15.20 to - 0.77, GRADE: Very low). For homeostatic model assessment for insulin resistance (HOMA-IR), the MD was 0.04 (CI = 0.08 to 0.16, GRADE: Moderate). The MD for interleukin 6 was 0.00 pg/mL (CI = - 0.01 to 0.00, GRADE: Low). For tumor necrosis factor alpha (TNF-α), the standardized mean difference (SMD) was - 0.52 pg/mL (CI = 0.85 to 0.19 GRADE: Very low) when compared with the control interventions. The certainty of the evidence for the other outcomes it is very low.

CONCLUSION

Our findings suggest that anthocyanin-rich foods could improve certain cardiometabolic markers (e.g., TC, TG, LDL, and TNF-α) among individuals with MetS (with very low quality evidence according to GRADE), compared with placebo or other control interventions.

PROSPERO REGISTRATION NUMBER

CRD42020187287.

Chlorogenic acid improves anti-lipogenic activity of metformin by positive regulating of AMPK signaling in HepG2 cells

Metformin improves lipid profile, however, combination therapy is developing to increase its effectiveness and reduce the deleterious effects of metformin. Chlorogenic acid (CGA) has exhibited lipid-lowering effects. This study aimed to investigate the combined effect of metformin and CGA on lipid accumulation, as well as to elucidate the engaged mechanism in HepG2 cells. To find the non-lethal doses of metformin and CGA, MTT assay was performed. High Glucose (HG) at 33 mM was used to induce lipogenesis in HepG2 cells. Following treatment with different concentrations of metformin and CGA, total lipid content (Oil Red O-staining), triglyceride level, the genes expression of SREBP-1c and FAS, and phosphorylation of AMPK and ACC were measured. Both Metformin and CGA decreased HG-induced lipid accumulation individually, by decreasing total lipid content and triglyceride level. The lowest effective doses of metformin and CGA were 0.25 mM and 5 μM, respectively, which significantly reduced SREBP-1c and FAS genes expression. The combination of these concentrations reinforced these effects. The phosphorylation of AMPK and ACC were more increased by metformin in combination with CGA than both individually. Our findings suggest that CGA synergistically enhances metformin lipid reducing action via the regulating of involved factors in fatty acid synthesis. Therefore, co-administration of metformin with CGA may have further medical value in treating lipid metabolism disorders.

Resveratrol in Treating Diabetes and Its Cardiovascular Complications: A Review of Its Mechanisms of Action

Diabetes mellitus (DM) is one of the most prevalent chronic diseases worldwide. High morbidity and mortality caused by DM are closely linked to its complications in multiple organs/tissues, including cardiovascular complications, diabetic nephropathy, and diabetic neuropathy. Resveratrol is a plant-derived polyphenolic compound with pleiotropic protective effects, ranging from antioxidant and anti-inflammatory to hypoglycemic effects. Recent studies strongly suggest that the consumption of resveratrol offers protection against diabetes and its cardiovascular complications. The protective effects of resveratrol involve the regulation of multiple signaling pathways, including inhibition of oxidative stress and inflammation, enhancement of insulin sensitivity, induction of autophagy, regulation of lipid metabolism, promotion of GLUT4 expression, and translocation, and activation of SIRT1/AMPK signaling axis. The cardiovascular protective effects of resveratrol have been recently reviewed in the literature, but the role of resveratrol in preventing diabetes mellitus and its cardiovascular complications has not been systematically reviewed. Therefore, in this review, we summarize the pharmacological effects and mechanisms of action of resveratrol based on in vitro and in vivo studies, highlighting the therapeutic potential of resveratrol in the prevention and treatment of diabetes and its cardiovascular complications.

Ligustrum japonicum Thunb. Fruits Exert Antiosteoporotic Properties in Bone Marrow-Derived Mesenchymal Stromal Cells via Regulation of Adipocyte and Osteoblast Differentiation

Ligustrum japonicum fruits have been used as a part of traditional medicinal practices and supplements in Korea and Japan. It has been reported to possess various bioactivities, but its antiosteoporotic potential and active substances have not been reported yet. The present study followed an ALP activity and lipid accumulation-guided screening of L. japonicum fruits for antiosteoporotic compounds and isolated salidroside as an active compound. Antiosteoporotic effects of L. japonicum fruits and salidroside were examined in mesenchymal stromal cells by their ability to enhance osteoblast formation by increased ALP activity and osteogenic marker gene expression while suppressing adipogenesis by inhibition of lipid accumulation and adipocyte marker gene expressions. Results showed that salidroside was able to enhance osteoblast differentiation via Wnt/BMP signaling pathway overactivation and suppress the PPARγ-mediated adipocyte differentiation, both through the MAPK pathway. In conclusion, L. japonicum fruits were suggested to possess antiosteoporotic activities and to be a source of antiosteoporotic substances such as salidroside.

Discovery of C-9 Modified Berberine Derivatives as Novel Lipid-Lowering Agents

Berberine (BBR), a kind of quaternary ammonium benzylisoquinoline alkaloids with multiple pharmacological activities, has been regarded as a promising lipid-lowering agent in the field of drug repurposing. Particularly, the chemical modification at the C-9 position of BBR can remarkably improve its lipid-lowering efficacy. In this study, thirteen novel BBR derivatives were rationally designed, synthesized, and evaluated by preliminary pharmacological tests. The results showed that most compounds exhibited more potent hypolipidemic activities when compared with BBR and simvastatin. Among these compounds, compound 2h-1 and 2h-2 exhibited better activity profiling in these four tests involving with inhibition of total cholesterol (TCHO), triglyceride (TG), and low-density lipoprotein cholesterol (LDLC) and the increase of high-density lipoprotein cholesterol (HDLC). Correspondingly, the BBR analogs with 9-O-cinnamic moiety probably exhibited potent lipid-lowering activity, and should be exploited as an important versatile template for the development of BBR-like lipid-lowering agents.

A review of saponin intervention in metabolic syndrome suggests further study on intestinal microbiota

Metabolic syndrome (MetS) is a series of symptoms including insulin resistance, obesity, dyslipidemia, elevated fasting blood glucose levels, and hepatic steatosis. As a key criterion in MetS, the onset of insulin resistance is related to abnormal levels of circulating free fatty acids and adipokines. It has been discovered in recent years that metabolites and pathogen-associated molecular patterns of intestinal/gut microbiota are also important factors that cause insulin resistance and MetS. Saponins are the main components of many botanicals and traditional Chinese medicines (TCMs), such as ginseng, platycodon, licorice, and alfalfa. They have poor bioavailability, but can be transformed into secondary glycosides and aglycones by intestinal microbiota, further being absorbed. Based on in vivo and in vitro data, we found that saponins and their secondary metabolites have a preventive effect on MetS, and the effective targets are distributed in the intestine and other organs in human body. Intestinal targets involve pancreatic lipase, dietary cholesterol, and intestinal microbiota. Other targets include central appetite, nuclear receptors such as PPAR and LXR, AMPK signaling pathway and adipokines levels, etc. In view of the poor bioavailability of saponins, it is inferred that targets for prototype-saponins to interfere with MetS is mainly located in the intestine, and the activation of other targets may be related to secondary glycosides and aglycones transformed from saponins by intestinal flora. We suggest that the role of intestinal microbiota in saponin intervention in MetS should be further investigated.

3,5-dicaffeoyl‑epi-quinic acid from Atriplex gmelinii enhances the osteoblast differentiation of bone marrow-derived human mesenchymal stromal cells via WnT/BMP signaling and suppresses adipocyte differentiation via AMPK activation

BACKGROUND

Impaired bone formation is one of the reasons behind osteoporosis. Alterations in the patterns of mesenchymal stromal cell differentiation towards adipocytes instead of osteoblasts contribute to osteoporosis progression. Natural anti-osteoporotic agents are effective and safe alternatives for osteoporosis treatment.

PURPOSE

In this context, 3,5-dicaffeoyl‑epi-quinic acid (DCEQA) which is a derivative of chlorogenic acid with reported bioactivities was studied for its osteogenic differentiation enhancing potential in vitro.

METHODS

Anti-osteoporotic effects of DCEQA were investigated in human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) which were induced to differentiate into osteoblasts or adipocytes with or without DCEQA treatment. Changes in the osteogenic and adipogenic markers such as ALP activity and lipid accumulation, respectively, were observed along with differentiation-specific activation of mitogen activated protein kinase (MAPK) pathways.

RESULTS

At 10 μM concentration, DCEQA increased the proliferation of bone marrow-derived human mesenchymal stromal cells (hBM-MSCs) during osteoblast differentiation. The expression of osteogenic markers ALP, osteocalcin, Runx2, BMP2 and Wnt 10a was upregulated by DCEQA treatment. The ALP activity and extracellular mineralization were also increased. DCEQA elevated the phosphorylation levels of p38 and JNK MAPKs as well as the activation of β-catenin and Smad1/5. DCEQA suppressed the lipid accumulation and downregulated expression of adipogenic markers PPARγ, C/EBPα and SREBP1c in adipo-induced hBM-MSCs. DCEQA also decreased the phosphorylation of p38 and ERK MAPKs and stimulated the activation of AMPK in hBM-MSC adipocytes.

CONCLUSION

DCEQA was suggested to enhance osteoblast differentiation via stimulating Wnt/BMP signaling. The adipocyte differentiation inhibitory effect of DCEQA was suggested to arise from its ability to increase AMPK phosphorylation. Overall, DCEQA was shown to possess osteogenesis enhancing and adipogenesis inhibitory properties which might facilitate its use against osteoporotic conditions.

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.

Development of a Novel Anti-Obesity Compound with Inhibiting Properties on the Lipid Accumulation in 3T3-L1 Adipocytes

Background:

Obesity as a developing global challenge can be characterized by increase in adipocyte number and size arising from adipogenesis. Control of adipogenesis, as a potential strategy, can prevent and manage obesity. So far, the effectiveness of herbal medicine and active ingredients therapies for obesity and metabolic syndrome treatment has been investigated. In this study, a novel combination of berberine, catechin, and capsaicin was developed, and their effect on 3T3-L1 adipocytes was investigated.

Methods:

The effect of active ingredient on the cell viability was assessed by MTT assay. Adipocytes were treated with various concentrations of berberine (3 and 6.25 μM), catechin (6.25 and 12.5 μM), and capsaicin (6.25 and 12.5 μM) alone and in combination.

Results:

All active ingredients did not affect the cell viability by MTT assay at different concentrations. The dual and triple combinations of three active ingredients showed excellent potential as anti-obese without any toxicity. The inhibitory effect of berberine, catechin, and capsaicin on the differentiation of 3T3-L1 preadipocytes was found to be dose-dependent. These results indicate that catechin in both doses may have a stronger effect than the two other active ingredients on the intracellular lipid accumulation. Also, the triple combination of the aforementioned ingredients showed better responses than their dual combination.

Conclusion:

This work is the first report to simultaneously investigate these three active ingredients in a single, dual, and triple formats. The berberine, catechin, and capsaicin co-treatment inhibits the adipogenesis during the differentiation process. This compound can be a prospective therapy for obesity and relevant diseases such as dyslipidemia.

Soybean extract increases telomerase reverse transcriptase protein expression in pancreatic β-cells of diabetes mellitus-induced rats

BACKGROUND A number of studies on the benefits of soybean (Glycine max (L.) Merr) in the treatment of diabetes mellitus (DM) have already been conducted; however, the effects of soybean extracts on telomerase reverse transcriptase (TERT) expression in improving telomerase activity in pancreatic cells is currently unknown. This study was aimed to evaluate the effects of soybean extracts on TERT protein expression in the pancreatic β-cells of rats with DM.  METHODS Sixty male Sprague-Dawley rats were randomly divided into six groups: (1) negative control (N); (2) DM rats induced by alloxan (DMA); (3) DM rats with glibenclamide (DMG; positive control); (4) DM rats with 1 mg/kgBW/day soybean extract (DM1E); (5) DM rats with 5 mg/kgBW/day soybean extract (DM5E); (6) DM rats with 25 mg/kgBW/day soybean extract (DM25E). The treatments were carried out over 28 days. The measured variables included fasting blood glucose (FBG) level, TERT protein expression, and the number of pancreatic β-cells.  RESULTS All parameters were measured against the diabetes control group. The FBG levels in rats DM1E, DM5E, and DM25E were significantly reduced on the 28th day (p < 0.05). TERT protein expression and the number of pancreatic β-cells (DM25E) also showed significant improvements compared to DM rats (p < 0.05).  CONCLUSIONS Soybean extracts can increase TERT protein expression in pancreatic β-cells in diabetes-induced rats. 

Evaluation of Polyphenolic Compounds and Pharmacological Activities in Hairy Root Cultures of Ligularia fischeri Turcz. f. spiciformis (Nakai)

A considerable amount of bioactive compounds have been used for the biopharmaceutical engineering to help human health and nutrition. Hairy root culture (HRC) or transgenic root is a favourable alternative technique for phytochemical production. Ligularia fischeri is a significant source of pharmaceutically important active compounds with an enormous range of health care applications. HRC of L. fischeri was developed using Agrobacterium rhizogenes for the production of polyphenolic compounds with antioxidant, antimicrobial, antidiabetic, anticancer and anti-inflammatory pharmaceutical activities. Hairy roots (HRs) were selected by morphological assessment, genetic and molecular analyses. The maximum accumulation of fresh mass (94.15 g/L) and dry mass (9.45 g/L) was recorded in MS liquid medium supplemented with 30 g/L sucrose at 28 days. Furthermore, HRs successfully produced numerous polyphenolic compounds, including six hydroxycinnamic acids, seven flavonols, seven hydroxybenzoic acids, vanillin, resveratrol, pyrogallol, homogentisic, and veratric acids, which were identified by UHPLC analysis. HRs produced higher total phenolic (185.65 mg/g), and flavonoid (5.25 mg/g) contents than non-transformed roots (125.55 mg/g and 3.75 mg/g). As a result of these metabolic changes, pharmaceutical activities were found higher in HRs than non-transformed roots (NTRs). The present study indicates that HRC has the potential to increase the content of beneficial polyphenolic compounds with higher potential pharmaceutical activities. To the best of our knowledge, the present study is the first report on enhancing the production of polyphenolic compounds with pharmaceutical activities from the HRCs of L. fischeri.

Pathobiological mechanisms underlying metabolic syndrome (MetS) in chronic obstructive pulmonary disease (COPD): clinical significance and therapeutic strategies

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and is currently the 4th largest cause of death in the world. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities (e.g. skeletal muscle wasting, ischemic heart disease, cognitive dysfunction) and infective viral and bacterial acute exacerbations (AECOPD). Current pharmacological treatments for COPD are relatively ineffective and the development of effective therapies has been severely hampered by the lack of understanding of the mechanisms and mediators underlying COPD. Since comorbidities have a tremendous impact on the prognosis and severity of COPD, the 2015 American Thoracic Society/European Respiratory Society (ATS/ERS) Research Statement on COPD urgently called for studies to elucidate the pathobiological mechanisms linking COPD to its comorbidities. It is now emerging that up to 50% of COPD patients have metabolic syndrome (MetS) as a comorbidity. It is currently not clear whether metabolic syndrome is an independent co-existing condition or a direct consequence of the progressive lung pathology in COPD patients. As MetS has important clinical implications on COPD outcomes, identification of disease mechanisms linking COPD to MetS is the key to effective therapy. In this comprehensive review, we discuss the potential mechanisms linking MetS to COPD and hence plausible therapeutic strategies to treat this debilitating comorbidity of COPD.

Treatment With Naringenin Elevates the Activity of Transcription Factor Nrf2 to Protect Pancreatic β-Cells From Streptozotocin-Induced Diabetes in vitro and in vivo

Chronic hyperglycemia and unusually high oxidative stress are the key contributors for diabetes in humans. Since nuclear factor E2-related factor 2 (Nrf2) controls the expression of antioxidant- and detoxification genes, it is hypothesized that targeted activation of Nrf2 using phytochemicals is likely to protect pancreatic β-cells, from oxidative damage, thereby mitigates the complications of diabetes. Naringenin is one such activator of Nrf2. However, it is currently not known whether the protective effect of naringenin against streptozotocin (STZ) induced damage is mediated by Nrf2 activation. Hence, the potential of naringenin to activate Nrf2 and protect pancreatic β-cells from STZ-induced damage in MIN6 cells is studied. In MIN6 cells, naringenin could activate Nrf2 and its target genes GST and NQO1, thereby inhibit cellular apoptosis. In animals, administration of 50 mg/kg body weight naringenin, for 45 days, significantly decreased STZ-induced blood glucose levels, normalized the lipid profile, and augmented the levels of antioxidants in pancreatic tissues. Immunohistochemical analysis measuring the number of insulin-positive cells in pancreas showed restoration of insulin expression similar to control animals. Furthermore, naringenin promoted glycolysis while inhibiting gluconeogenesis. In conclusion, naringenin could be a good anti-diabetic agent, which works by promoting Nrf2 levels and by decreasing cellular oxidative stress.

Beneficial Effects of an Aged Black Garlic Extract in the Metabolic and Vascular Alterations Induced by a High Fat/Sucrose Diet in Male Rats

Aged black garlic (ABG) is a functional food with antioxidant and anti-inflammatory properties. Recent studies also report its beneficial metabolic effects in a context of obesity or diabetes, although the mechanisms involved are poorly understood. The aim of this work was to analyze the effects of an ABG extract in the vascular and metabolic alterations induced by a high-fat/sucrose diet in rats. For this purpose, male Sprague–Dawley rats were fed either a standard chow (controls; n = 12) or a high-fat/sucrose diet (HFD; n = 24) for 16 weeks. From week 8 on, half of the HFD rats were treated with a commercial ABG extract concentrated in S-allyl cysteine and melanoidins (ABG10+®; 250 mg/kg daily by gavage; 5 mL/kg). ABG10+®-treated rats showed lower mean caloric intake, body weight, triglycerides, low density lipoprotein cholesterol (LDL-c), insulin and leptin serum concentrations and higher high density lipoprotein cholesterol (HDL-c) and adiponectin serum concentrations than non-treated rats. In the hypothalamus, ABG10+® treatment induced an increase in the gene expression of proopiomelanocortin (POMC) and a decrease in leptin receptor (ObR) mRNA levels. No significant changes were found in visceral adipose tissue except for an overexpression of β3-adrenergic receptor (β3-ADR) in ABG-treated rats. In subcutaneous adipose tissue, ABG10+® treatment decreased adipose weight and downregulated the gene expression of PPAR-γ, LPL, ObR and HSL. In brown adipose tissue, an overexpression of InsR, GLUT-4, UCP-1 and β3-ADR in ABG10+®-treated rats was found, whereas PPAR-γ mRNA levels were significantly decreased. Regarding vascular function, ABG10+® treatment attenuated the obesity-induced vasoconstriction in response to potassium chloride both in presence/absence of perivascular adipose tissue (PVAT). On the contrary, aorta segments from ABG-treated rats showed and improved relaxation in response to acetylcholine only when PVAT was present, with this fact possible being related to the decreased gene expression of proinflammatory cytokines in this tissue. In conclusion, ABG10+® administration partially improves the metabolic and vascular alterations induced by a high-fat/high-sucrose diet in rats through modifications in the gene expression of proteins and neuropeptides involved in inflammation, fat metabolism and food intake regulation. Further studies are required to assess the bioavailability of ABG between rats and humans.

Antihyperglycemic and Antilipidemic Effects of the Ethanol Extract Mixture of Ligularia fischeri and Momordica charantia in Type II Diabetes-Mimicking Mice

The extract of the Momordica charantia fruit (MCE) is recognized as an alternative treatment for diabetes. The extract of Ligularia fischeri leaves (LFE) is traditionally used as a folk medicine for treating inflammatory diseases in Korea as well. In this study, we investigated the synergistic effect of MCE combined with LFE on antihyperglycemic and antihyperlipidemic potentials. Based on the α-glucosidase inhibitory effect and promotion of adipocyte differentiation in the 3T3-L1 cell line, the MLM was prepared with MCE:LFE (8:2 weight:weight). MLM showed the synergistic effects in the promotion of the glucose uptake rate, suppression of dipeptidyl peptidase-4 (DPP-4) mRNA expression, upregulation of an insulin receptor substrate and glucose transporter type-4 expression, and an increase in insulin-associated signaling in C2C12 cells. In addition, the efficacy of peroxisome proliferator-activated receptor-γ agonism and glucose uptake rate by MLM supplementation was significantly enhanced in vitro. Then, the antihyperglycemic and antihyperlipidemic effects of MCE, LFE, and MLM at the dose of 50, 100, and 200 mg/kg/day (n = 6 per each group) were determined in streptozotocin (STZ)-insulted mice fed an atherogenic diet (ATH) for 4 weeks. In addition, MLM (50, 100, and 200 mg/kg/day, n = 5 per each group) was supplemented in ATH-fed db/db mice for 10 weeks. Compared with MCE or LFE alone, MLM supplementation led to a more significant reduction of glucose levels in both STZ/ATH and db/db/ATH mice as well as lowered lipid profiles in STZ/ATH mice. In addition, the stimulation of islet of Langerhans regeneration was more pronounced by MLM supplementation in both mice models. In conclusion, antihyperglycemic and antihyperlipidemic effects were strengthened by the combined extracts of L. fischeri and M. charantia (MLM) in diabetes-mimicking mice.

Evaluation of antidiabetic activity of biologically synthesized silver nanoparticles using Pouteria sapota in streptozotocin-induced diabetic rats

BACKGROUND

Medicinal plants and green synthesis of silver nanoparticles (AgNPs) have proven to be good sources of agents effective in the treatment of diabetes mellitus. The present study focused on the green synthesis of AgNPs from the aqueous leaf extract of Pouteria sapota in order to evaluate the in vitro and in vivo antidiabetic properties of this extract and the synthesized AgNPs.

METHODS

The AgNPs were biologically synthesized under ambient conditions from an aqueous leaf extract of P. sapota using the hot percolation method and were characterized using spectroscopic methods, X-ray diffraction, and scanning electron microscopy. The in vitro antidiabetic activity of the aqueous leaf extract and AgNPs was confirmed by non-enzymatic glycosylation of hemoglobin, glucose uptake by yeast cells following exposure of cells to 5 or 10 mmol/L glucose solution, and inhibition of α-amylase. Further, in vivo antidiabetic activity was assessed in streptozotocin-induced rats. Rats were treated with aqueous leaf extract (100 mg/kg) or AgNPs (10 mg/kg) for 28 days. Following treatment, rats were killed for biochemical and histopathological analysis of kidney and liver samples.

RESULTS

A significant reduction in blood sugar levels was noted in rats treated with leaf extract or AgNPs. Results of in vitro and in vivo analyses in rats treated with leaf extract or AgNPs show that both the extract and the biologically synthesized AgNPs have antidiabetic activity.

CONCLUSION

The aqueous leaf extract of P. sapota and AgNPs exhibited efficient antidiabetic activity in the rat model of diabetes and therefore could have potential for development for medical applications in the future.

Genistein: A Novel Anthocyanin Synthesis Promoter that Directly Regulates Biosynthetic Genes in Red Cabbage in a Light-Dependent Way

Genistein (GNT), an isoflavone, is used in the clinical treatment of various health disorders. GNT is found in primary food source plants and some medical plants. However, studies on the functions of GNT in plants are rarely reported. In this study, we demonstrated that GNT plays an important role in promoting anthocyanin accumulation in red cabbage. GNT solutions (10, 20, 30, 40, and 50 mg/L) as foliar fertilizers were applied to red cabbage. Consequently, anthocyanin accumulation in red cabbage increased in a light-dependent manner. GNT solution at 30 mg/L exhibited the optimal effect on anthocyanin accumulation, which was twice that of the control. Quantitative real-time PCR analysis indicated that GNT application upregulated the expression of all structural genes, contributing to anthocyanin biosynthesis under light conditions. Under dark conditions, GNT exerted no significant promotive effect on anthocyanin accumulation; only early biosynthetic genes of anthocyanin biosynthesis responded to GNT. The promotive effect of GNT on anthocyanin biosynthesis is directly attributable to the regulation of structural gene expression. Transcription factors exhibited no response to GNT. The levels of anthocyanin in red cabbage positively correlated with the enzyme activities of antioxidant systems. This finding correlation suggested that the promotive effect of GNT on anthocyanin levels was correlated with improved antioxidant activity in the red cabbage.

Astilbin improves potassium oxonate-induced hyperuricemia and kidney injury through regulating oxidative stress and inflammation response in mice

Astilbin is a flavonoid compound derived from the rhizome of Smilax china L. The effects and possible molecular mechanisms of astilbin on potassium oxonate-induced hyperuricemia mice were investigated in this study. Different dosages of astilbin (5, 10, and 20mg/kg) were administered to induce hyperuricemic mice. The results demonstrated that the serum uric acid (Sur) level was significantly decreased by increasing the urinary uric acid (Uur) level and fractional excretion of urate (FEUA) with astilbin, related with suppressing role in meditation of Glucose transporter 9 (GLUT9), Human urate transporter 1 (URAT1) expression and up-regulation of ABCG2, Organic anion transporter 1/3 (OAT1/3) and Organic cation transporter 1 (OCT1). In addition, kidney function parameters, including serum creatinine (Scr) and blood urea nitrogen (BUN) were restored in astilbin-treated hyperuricemic rats. Further investigation indicated that astilbin prevented the renal damage against the expression of Thioredoxin-interacting protein (TXNIP) and its related inflammation signal pathway, including NLR pyrin domain-containing 3/Nuclear factor κB (NLRP3/NF-κB), which is associated with the up-regulation of interleukin-1β (IL-1β) and interleukin-18 (IL-18), and also presented a renal protective role by suppression oxidative stress. Moreover, astilbin inhibited activation of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) cascade and over-expression of suppressor of cytokine signaling 3 (SOCS3) in the kidneys of potassium oxonate-induced mice. These findings provide potent evidence and therapeutic strategy for astilbin as a safe and promising compound in the development of a disease-modifying drug due to its function against hyperuricaemia and renal injury induced by potassium oxonate.

Genistein supplementation prevents weight gain but promotes oxidative stress and inflammation in the vasculature of female obese ob/ob mice

Obesity, a state of chronic low-grade inflammation, is strongly associated with the development of hypertension and diabetes. Superoxide, a free radical elevated in obese individuals, promotes hypertension through scavenging the endogenous vasodilator nitric oxide. The hypothesis was a genistein-enriched diet would promote weight loss and reduce oxidative stress and inflammation in the vasculature of intact female ob/ob mice. Aortas and mesenteric arteries were isolated from female ob/ob mice fed genistein-free (0mg genistein/kg diet; n=6), standard chow (200-300mg genistein/kg diet; n=11) or genistein-enriched (600mg genistein/kg diet; n=9) diets for 4weeks. Sections of isolated vessels were labeled with the superoxide indicator dihydroethidium and fluorescence was measured by confocal microscopy. Protein expression of the inflammatory marker inducible nitric oxide synthase (iNOS) was measured in the perivascular adipose tissue (PVAT) surrounding each vessel and plasma concentrations of superoxide dismutase (SOD) were quantified. Genistein-enriched diet promoted less weight gain compared to animals fed standard chow (P=.008). Standard chow promoted increased superoxide in the aorta (P=.030) and mesenteric arteries (P=.024) compared to a diet devoid of genistein. At all tested concentrations, genistein significantly increased iNOS expression in mesenteric artery PVAT (vs. standard chow, P<.001; vs. genistein-enriched, P=.002) and tended to increase iNOS within the aortic PVAT (standard chow, P=.075) compared to the genistein-free group. Plasma SOD activity was significantly downregulated in genistein-enriched animals as compared to those fed a genistein-free diet (P=.028). In summary, although genistein prevents weight gain, it promotes vascular oxidative stress and inflammation in obese ovarian-intact female mice.

Microcirculatory effects of zinc on fructose-fed hamsters

BACKGROUND AND AIMS

Fructose is a major dietary component directly related to vascular dysfunction and diseases such as obesity, diabetes, and hypertension. Zinc is considered a non-pharmacological alternative for treating diabetes due to its antioxidant and hyperglycemia-lowering effects in diabetic animals. Therefore, the aim of this study was to evaluate the effects of dietary zinc supplementation on the microcirculatory parameters of fructose-fed hamsters.

METHODS AND RESULTS

Male hamsters (Mesocricetus auratus) were fed drinking water substituted by 10% fructose solution for 60 days, whereas control animals were fed drinking water alone. Their microcirculatory function was evaluated using cheek pouch preparation, as well as their blood glucose and serum insulin levels. Their microcirculatory responses to acetylcholine (ACh, an endothelium-dependent vasodilator) and to sodium nitroprusside (SNP, an endothelium-independent vasodilator) as well as the increase in macromolecular permeability induced by 30 min of ischemia/reperfusion (I/R) were noted. Endothelium-dependent vasodilation was significantly increased in control animals with high zinc supplementation compared to the groups without zinc supplementation. Zinc was able to protect against plasma leakage induced by I/R in all control and fructose-fed groups, although the microvascular permeability was higher in animals fed drinking water substituted by 10% fructose solution compared to those fed filtered drinking water alone.

CONCLUSION

Our results indicate that dietary zinc supplementation can improve microvascular dysfunction by increasing endothelial-dependent dilatation and reducing the increase in macromolecular permeability induced by I/R in fructose-fed animals.

Resveratrol exerts anti-obesity effects in high-fat diet obese mice and displays differential dosage effects on cytotoxicity, differentiation, and lipolysis in 3T3-L1 cells

Studies on resveratrol in a wide range of concentrations on obese mice and adipose cells are necessary to comprehend its range of diverse and contradictory effects. In this study, we examined the anti-obesity effects of resveratrol on high-fat diet (HFD)-induced obese mice at dosages ranging from 1 to 30 mg/kg treatment for 10 wk. We also evaluated the effects of resveratrol on cytotoxicity, proliferation, adipogenic differentiation, and lipolysis of 3T3-L1 cells at concentrations ranging from 0.03 to 100 μM. In HFD obese mice, resveratrol treatment for 10 wk without decreased calories intake significantly attenuated HFD-induced weight gain in a dose-dependent manner. Resveratrol treatment also protected against HFD-induced lipid deposition in adipose tissues and liver. In cultured 3T3-L1 preadipocytes, high dosage (10 to 100 μM) resveratrol treatment produced cytotoxicity in both preadipocytes and mature adipocytes. In contrast, low concentration resveratrol treatment (1 to 10 μM) significantly inhibited the capacity of 3T3-L1 cells differentiated into mature adipocytes. Low dose resveratrol treatment also downregulated peroxisome proliferator-activated receptor gamma (PPARγ) and perilipin protein expressions in differentiated adipocytes. Additionally, tumor necrosis factor alpha (TNFα)-induced lipolysis was inhibited by low concentration resveratrol treatment in mature adipocytes. At concentrations of 10-100 μM, resveratrol exerted cytotoxicity. In contrast, at concentrations of 1-10 μM resveratrol inhibited adipogenic differentiation in preadipocytes and suppressed lipolysis in mature adipocytes. Our results suggest that resveratrol possessed anti-obesity effects by induction of cytotoxicity at high dosage and that it influences preadipocyte differentiation and mature adipocyte lipolysis at low concentration.

Berberine and Its Role in Chronic Disease

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. It is found in such plants as Berberis [e.g. Berberis aquifolium (Oregon grape), Berberis vulgaris (barberry), Berberis aristata (tree turmeric)], Hydrastis canadensis (goldenseal), Xanthorhiza simplicissima (yellowroot), Phellodendron amurense ^[2] (Amur corktree), Coptis chinensis (Chinese goldthread), Tinospora cordifolia, Argemone mexicana (prickly poppy) and Eschscholzia californica (Californian poppy). In vitro it exerts significant anti-inflammatory and antioxidant activities. In animal models berberine has neuroprotective and cardiovascular protective effects. In humans, its lipid-lowering and insulin-resistance improving actions have clearly been demonstrated in numerous randomized clinical trials. Moreover, preliminary clinical evidence suggest the ability of berberine to reduce endothelial inflammation improving vascular health, even in patients already affected by cardiovascular diseases. Altogether the available evidences suggest a possible application of berberine use in the management of chronic cardiometabolic disorders.

Metabolites as novel biomarkers for childhood obesity-related traits in Mexican-American children

BACKGROUND/OBJECTIVES

Although newer approaches have identified several metabolites associated with obesity, there is paucity of such information in paediatric populations, especially among Mexican-Americans (MAs) who are at high risk of obesity. Therefore, we performed a global serum metabolite screening in MA children to identify biomarkers of childhood obesity.

METHODS

We selected 15 normal-weight, 13 overweight and 14 obese MA children (6-17 years) and performed global serum metabolite screening using ultra-performance liquid chromatography/quadruple orthogonal acceleration time of flight tandem micro mass spectrometer. Metabolite values were analysed to assess mean differences among groups using one-way analysis of variance, to test for linear trend across groups and to examine Pearson's correlations between them and seven cardiometabolic traits (CMTs): body mass index, waist circumference, systolic blood pressure, diastolic blood pressure, homeostasis model of assessment-insulin resistance, triglycerides and high-density lipoprotein cholesterol.

RESULTS

We identified 14 metabolites exhibiting differences between groups as well as linear trend across groups with nominal statistical significance. After adjustment for multiple testing, mean differences and linear trends across groups remained significant (P < 5.9 × 10(-5) ) for L-thyronine, bradykinin and naringenin. Of the examined metabolite-CMT trait pairs, all metabolites except for 2-methylbutyroylcarnitine were nominally associated with two or more CMTs, some exhibiting significance even after accounting for multiple testing (P < 3.6 × 10(-3) ).

CONCLUSIONS

To our knowledge, this study - albeit pilot in nature - is the first study to identify these metabolites as novel biomarkers of childhood obesity and its correlates. These findings signify the need for future systematic investigations of metabolic pathways underlying childhood obesity.

Resveratrol improves high-fructose-induced vascular dysfunction in rats

High levels of fructose in the diet results in metabolic abnormalities and vascular disorders. In this study, the effect of resveratrol (RES) on vascular relaxation and contraction responses was examined in the aorta of high-fructose (HFr)-fed rats. mRNA expressions of aortic sirtuin 1 (SIRT1), GLUT5, and aldolase B were also investigated. Rats were given fructose (30%) and (or) RES (50 mg·L−1) in their drinking water for 8 weeks. In the HFr-fed rats, plasma levels of arginine and the ratio of arginine:asymmetric dimethylarginine (ADMA) decreased, whereas leptin levels increased. Decreased relaxation and increased contractile responses were detected in aortic rings. However, the aortic expressions of SIRT1, GLUT5, and aldolase B remained unchanged. RES treatment restored HFr-induced vascular dysfunction without improvements in insulin resistance. Treatment of HFr-fed rats with RES increased plasma levels of arginine and the l-arginine:ADMA ratio, and decreased plasma levels of leptin. RES increased SIRT1 expression, but decreased the expression of GLUT5 and aldolase B in aortas from HFr-fed rats. These results suggest that RES contributes to the restoration of HFr-induced vascular dysfunction in rats, at least in part, by up-regulation of SIRT 1 and down-regulation of GLUT5 and aldolase B in the aorta. Moreover, RES may have a positive influence on vasculature by partly restoring the plasma arginine:ADMA ratio and leptin levels.

Xanthohumol lowers body weight and fasting plasma glucose in obese male Zucker fa/fa rats

Obesity contributes to increased risk for several chronic diseases including cardiovascular disease and type 2 diabetes. Xanthohumol, a prenylated flavonoid from hops (Humulus lupulus), was tested for efficacy on biomarkers of metabolic syndrome in 4 week old Zucker fa/fa rats, a rodent model of obesity. Rats received daily oral doses of xanthohumol at 0, 1.86, 5.64, and 16.9 mg/kg BW for 6 weeks. All rats were maintained on a high fat (60% kcal) AIN-93G diet for 3 weeks to induce severe obesity followed by a normal AIN-93G (15% kcal fat) diet for the last 3 weeks of the study. Weekly food intake and body weight were recorded. Plasma cholesterol, glucose, insulin, triglyceride, and monocyte chemoattractant protein-1 (MCP-1) levels were assessed using commercial assay kits. Plasma and liver tissue levels of XN and its metabolites were determined by liquid-chromatography tandem mass spectrometry. Plasma and liver tissue levels of xanthohumol were similar between low and medium dose groups and significantly (p<0.05) elevated in the highest dose group. There was a dose-dependent effect on body weight and plasma glucose levels. The highest dose group (n=6) had significantly lower plasma glucose levels compared to the control group (n=6) in male but not female rats. There was also a significant decrease in body weight for male rats in the highest dose group (16.9 mg/kg BW) compared to rats that received no xanthohumol, which was also not seen for female rats. Plasma cholesterol, insulin, triglycerides, and MCP-1 as well as food intake were not affected by treatment. The findings suggest that xanthohumol has beneficial effects on markers of metabolic syndrome.

Pleiotropic effects of genistein in metabolic, inflammatory, and malignant diseases

Genistein is a soy-derived biologically active isoflavone that exhibits diverse health-promoting effects. An increasing body of evidence shows that genistein influences lipid homeostasis and insulin resistance, counteracts inflammatory cytokines, and possesses antidiabetic properties. Genistein also impedes cancer progression by promoting apoptosis, inducing cell cycle arrest, modulating intracellular signaling pathways, and inhibiting angiogenesis and metastasis of neoplastic cells. This review summarizes the pleiotropic functions of genistein in common health disorders such as metabolic syndrome, chronic inflammatory diseases, and cancer. In the current era of uncontrolled health expenditure, a focus on the clinical development of nutritional agents with the capacity to prevent a variety of common health disorders is needed. As a micronutrient that exerts multifaceted effects ranging from antidiabetic to anticarcinogenic functions, genistein should be clinically developed further for use in the prevention and treatment of a variety of health disorders.

Dietary isoflavone intake, urinary isoflavone level, and their relationship with metabolic syndrome diagnostic components in korean postmenopausal women

Recent studies have suggested that natural agents such as isoflavones, resveratrol, and anthocyanin have beneficial effects on metabolic syndrome-related disorders. The objective of this study was to evaluate dietary isoflavone intake, urinary isoflavone level, and their relationship with the risk of metabolic syndrome (MetS) among Korean postmenopausal women. The subjects included 46 MetS and 60 controls. The MetS risk score was determined by adding the number of risk factors such as waist circumference, blood pressure (BP) and levels of triglyceride (TG), HDL-cholesterol, and glucose. Dietary isoflavone intake was not significantly different between the MetS and control groups; however, the urinary daidzein level was significantly higher in the MetS subjects compared to that of the controls. Subjects with high TG had higher urinary daidzein and isoflavone (daidzein + genistein) levels than those without such abnormalities. But, the MetS risk score showed no significant correlation with urinary daidzein, genistein, and isoflavone excretions.

Cardiac dysfunction and oxidative stress in the metabolic syndrome: an update on antioxidant therapies

The metabolic syndrome (MetS) is a cluster of risk factors including obesity, insulin resistance, dyslipidemia, elevated blood pressure and glucose intolerance. The MetS increases the risk for cardiovascular disease (CVD) and type 2 diabetes. Each component of the MetS causes cardiac dysfunction and their combination carries additional risk. The mechanisms underlying cardiac dysfunction in the MetS are complex and might include lipid accumulation, increased fibrosis and stiffness, altered calcium homeostasis, abnormal autophagy, altered substrate utilization, mitochondrial dysfunction and increased oxidative stress. Mitochondrial and extra-mitochondrial sources of reactive oxygen species (ROS) and reduced antioxidant defense mechanisms characterize the myocardium of humans and animals with the MetS. The mechanisms for increased cardiac oxidative stress in the MetS are not fully understood but include increased fatty acid oxidation, mitochondrial dysfunction and enhanced NADPH oxidase activity. Therapies aimed to reduce oxidative stress and enhance antioxidant defense have been employed to reduce cardiac dysfunction in the MetS in animals. In contrast, large scale clinical trials using antioxidants therapies for the treatment of CVD have been disappointing because of the lack of efficacy and undesired side effects. The focus of this review is to summarize the current knowledge about the mechanisms underlying cardiac dysfunction in the MetS with a special interest in the role of oxidative stress. Finally, we will update the reader on the results obtained with natural antioxidant and mitochondria-targeted antioxidant therapies for the treatment of CVD in the MetS.

Berberine on metabolic and cardiovascular risk factors: an analysis from preclinical evidences to clinical trials

INTRODUCTION

Type 2 diabetes mellitus and hypercholesterolemia have proven to give an increased incidence of cardiovascular diseases (CVD). Recent studies have suggested that the natural alkaloid berberine could have pharmacological activities potentially useful in diabetes and hypercholesterolemia management.

AREAS COVERED

The aim of this review is to evaluate the metabolic properties of the natural alkaloid berberine, and its potential application to the treatment of diabetes and CVD prevention.

EXPERT OPINION

Berberine proved to be effective in improving glycemic control and lipid profile. The modern investigation on berberine pharmacological activity is actually developing and numerous scientific evidences are actually in progress and reported in international congresses. The near future perspective is the isolation or neo-synthesis of berberine analogs with a higher bioavailability. The anti-hyperlipidemic and anti-diabetic effects of berberine have to be related to markers of improvement in organ damage in humans; longer trials are needed to better evaluate the safety profile of the molecule, when administered alone or in association with other anti-hyperlipidemic or anti-diabetic drugs, especially in the European population.

Resveratrol attenuates oxidative stress and prevents steatosis and hypertension in obese rats programmed by early weaning

We hypothesized that resveratrol, a natural phytoalexin found in grapes, can prevent oxidative stress, obesity and its related disturbances in obese rats programmed by early weaning. Lactating Wistar rats were separated into two groups: early weaning (EW) - dams who were wrapped with a bandage to interrupt the lactation in the last 3 days of lactation; control - dams whose pups had free access to milk during all lactation. At the 150th day, EW offspring were randomly subdivided into EW+resveratrol (EW+Res) - resveratrol (30 mg/kg/day); EW+vehicle (EW) - rats that received 0.5% (w/v) aqueous methylcellulose. The control group received vehicle. Rats were treated by gavage daily for 30 days. EW offspring developed hyperphagia, higher body weight, visceral obesity, higher systolic (SBP) and diastolic blood pressure (DBP) (+15% and +20%, respectively; P<.05) and higher serum triglycerides (TG) and low-density lipoprotein but lower high-density lipoprotein (+55%, +33% and -13%, respectively; P<.05). Resveratrol normalized food intake, SBP and DBP and prevented obesity and dyslipidemia in EW+Res. EW rats had higher plasma and liver thiobarbituric-acid-reactive substances (TBARS) and lower plasma superoxide dismutase (SOD) and liver glutathione peroxidase activities (+51%, +18%, -58%, -31%, respectively; P<.05), and resveratrol normalized both plasma and liver TBARS and increased the activity of SOD and catalase in plasma. EW rats presented liver steatosis and higher liver TG, and resveratrol prevented these hepatic alterations. In conclusion, this study demonstrated a potential therapeutic use of resveratrol in preventing obesity and oxidative stress and reducing the risk of hypertension, dyslipidemia and steatosis in adult rats programmed by early weaning.

Investigation of the anxiolytic effects of naringenin, a component of Mentha aquatica, in the male Sprague-Dawley rat

This was a prospective, randomized, between-subjects experimental study to investigate the anxiolytic effects of naringenin, a component of mentha aquatica, and its potential interaction with the benzodiazepine binding site on the γ-aminobutyric acid (GABAA) receptor in the rat. Fifty-five rats were assigned to one of 5 groups with 11 rats per group: control, naringenin, midazolam, midazolam with naringenin, and flumazenil with naringenin. The elevated plus maze measured the behavioral components of anxiety and motor movements. Our data suggest that naringenin does not produce anxiolysis by modulation of the GABAA receptor; however, the findings indicate that naringenin decreases motor movements (P < .05).

Antidiabetic properties of berberine: from cellular pharmacology to clinical effects

Berberine is an alkaloid that is highly concentrated in the roots, rhizomes, and stem bark of various plants. It affects glucose metabolism, increasing insulin secretion, stimulating glycolysis, suppressing adipogenesis, inhibiting mitochondrial function, activating the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway, and increasing glycokinase activity. Berberine also increases glucose transporter-4 (GLUT-4) and glucagon-like peptide-1 (GLP-1) levels. On GLP-1 receptor activation, adenylyl cyclase is activated, and cyclic adenosine monophosphate is generated, leading to activation of second messenger pathways and closure of adenosine triphosphate-dependent potassium channels. Increased intracellular potassium causes depolarization, and calcium influx through the voltage-dependent calcium channels occurs. This intracellular calcium increase stimulates the migration and exocytosis of the insulin granules. In glucose-consuming tissues, such as adipose, or liver or muscle cells, berberine affects both GLUT-4 and retinol-binding protein-4 in favor of glucose uptake into cells; stimulates glycolysis by AMPK activation; and has effects on the peroxisome proliferator-activated receptor γ molecular targets and on the phosphorylation of insulin receptor substrate-1, finally resulting in decreased insulin resistance. Moreover, recent studies suggest that berberine could have a direct action on carbohydrate metabolism in the intestine. The antidiabetic and insulin-sensitizing effect of berberine has also been confirmed in a few relatively small, short-term clinical trials. The tolerability is high for low dosages, with some gastrointestinal complaints appearing to be associated with use of high dosages.