Hydro-Alcoholic Cinnamon Extract, Enhances Glucose Transporter Isotype-4 Translocation from Intracellular Compartments into the Cytoplasmic Membrane of C2C12 Myotubes

Natural activators of AMPK signaling: potential role in the management of type-2 diabetes

Adenosine 5'-monophosphate-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase involved in the homeostasis of cellular energy. AMPK has developed as an appealing clinical target for the diagnosis of multiple metabolic diseases such as diabetes mellitus, obesity, inflammation, and cancer. Genetic and pharmacological studies indicate that AMPK is needed in response to glucose deficiency, dietary restriction, and increased physical activity for preserving glucose homeostasis. After activation, AMPK influences metabolic mechanisms contributing to enhanced ATP production, thus growing processes that absorb ATP simultaneously. In this review, several natural products have been discussed which enhance the sensitivity of AMPK and alleviate sub complications or different pathways by which such AMPK triggers can be addressed. AMPK Natural products as potential AMPK activators can be developed as alternate pharmacological intervention to reverse metabolic disorders including type 2 diabetes.

Efficacy of Young Cinnamomum zeylanicum Blume Bark on Hyperglycemia and PTPase Activity in Type 2 Diabetes

Diabetes is a major public health concern and natural easy-going remedies are being searched. Since Cinnamomum zeylanicum Blume has a low coumarin concentration and possible insulin-enhancing properties, it is preferred over all other cinnamon species. Although similar research has been done on humans, there have been very few studies on this particular species, and none among South Asians. Moreover, no human trial that properly described their intervening agent (C. zeylanicum) and checked its efficacy at the molecular level along with clinical variables was conducted. Therefore, the current research aimed to explore the effects of C. zeylanicum on the glycemic index, lipid profile, and expression of the protein tyrosine phosphatase 1 B (PTP1B) enzyme in the peripheral blood mononuclear cells (PBMC) in type 2 diabetes. We examined the presence of bioactive compounds in young C. zeylanicum bark (Alba grade) from native Sri Lanka using gas chromatography-mass spectrometry, high-performance thin-layer chromatography, and thin-layer chromatography before introducing it in the clinical study where trans-Cinnamaldehyde was found to be a major chemical constituent (>60%). Then, from January 2020 to March 2022, a randomized double-blinded placebo-controlled trial was carried out in the Diabetic Clinic at AIIMS Rishikesh. A total of 154 diabetic patients were enrolled and were taken either cinnamon or placebo capsules (1.5 g/day) for 120 days on an empty stomach with warm water along with their conventional treatment. Reduction in fasting blood glucose levels in the cinnamon group was found -35.50% (95% CI, -173 to 58.4), whereas in the placebo group change was 5.00% (95% CI, -165 to 224). For glycosylated hemoglobin, it differed -0.85% (95% CI, -8.2 to 1.6) in the cinnamon group compared to the placebo where it was found 0.15% (95% CI, -6.1 to 5.5). PTP1B expression in PBMC was determined from pre- and post-trial blood samples using the Western Blot, and significant inhibition was also observed (p=0.039). The study result depicts, C. zeylanicum is emerging as a beneficial plant for type 2 diabetes in Northern India and could be used as an adjunctive treatment rather than as a standalone managerial remedy.

The evolving roles of alarin in physiological and disease conditions, and its future potential clinical implications

Alarin is a member of the galanin family of neuropeptides that is widely expressed in the central nervous system and peripheral tissues in humans and rodents. It was initially isolated fifteen years ago in ganglionic cells of human neuroblastoma. Subsequently, it was demonstrated to be broadly distributed in the blood vessels, skin, eyes, peripheral and central nervous systems, thymus, gastrointestinal tract, and endocrine organs of different species. Alarin is a 25 amino acid neuropeptide derived from the alternative splicing of the GALP gene, missing exon 3. It is found to be involved in several physiological functions that include feeding behavior, energy homeostasis, glucose homeostasis, body temperature, and reproduction. It has also vasoactive, anti-inflammatory, anti-edema, and antimicrobial activities. However, the physiological effects of alarin have not been fully elucidated and the receptors that mediate these effects are not currently known. Unearthing the novel biological effects of alarin and its unidentified receptors will therefore be a task in future biomedical research. In addition, alarin is involved in various disease conditions, such as metabolic syndrome, obesity, insulin resistance, type 2 diabetes, diabetic retinopathy, hypertension, cardiac fibrosis, polycystic ovarian syndrome, and depression. Thus, alarin may serve as a promising tool for future pharmacological treatment and diagnosis. But further research is awaited to confirm whether alarin has a protective or pathological role in these diseases. This article provides a comprehensive review on the evolving implications of alarin in a variety of physiological and disease conditions, and its future perspectives.

Hydro-alcoholic extract of Morus nigra reduces fasting blood glucose and HbA1c% in diabetic patients, probably via competitive and allosteric interaction with alpha-glucosidase enzyme; a clinical trial and in silico analysis

OBJECTIVES

1-Deoxynojirimycin (1-DNJ), the main active component found in Morus nigra (black mulberry) is reported to be effective in controlling diabetes. We have evaluated the effect of hydro-alcoholic extract of M. nigra leaves on the fasting blood glucose (FBS) and hemoglobin A1c% (HbA1c%) in diabetic patients. Furthermore, we compared the interaction of 1-DNJ and glucose molecules with the alpha-glucosidase enzyme, which has a critical role in the lysis of glucose-based polymers in human cells.

METHODS

4% hydro-alcoholic extract was prepared from black mulberry leaves. Patients in treatment (n=50) and control (n=50) groups received 3 mL extract or placebo in water, respectively, and three times a day. Fasting blood glucose and HbA1c% were evaluated before and after three months of evaluation. Potential binding sites of 1-DNJ or glucose on the enzyme glucosidase found by docking study. Docking scores were obtained using an energy minimization method by Molegro Virtual Docker software. The Mean ± SD of each variable was compared between groups at the 95% significant level.

RESULTS

Age mean ± SD was equal to 54.79 ± 9.203 (38-69) years. There was no significant difference between intervention and placebo groups considering FBS (p=0.633) but was for HbA1c% (p=0.0011), before treatment. After three months, both FBS and HbA1c% were significantly reduced in patients under mulberry leaves extract-treatment. FBS changed was from 182.23 ± 38.65 to 161.23 ± 22.14 mg/dL in treatment group (p<0.001) and from 178.45 ± 39.46 to 166.23 ± 29.64 mg/dL in control group (p<0.001). HbA1c was changed from 7.23 ± 0.25 to 6.13 ± 0.61% in treatment group (p<0.001) and from 7.65 ± 0.85 to 7.12 ± 0.33% in control group (p=0.854). Docking results showed that 1-DNJ binds more efficiently, and with a significant score than glucose, to human alpha-glucosidase.

CONCLUSIONS

This clinical trial and virtual analysis showed that a hydro-alcoholic extract of black mulberry (M. nigra) leaf may be efficient in reducing the blood glucose and HbA1c% in diabetic patients. Furthermore, docking studies propose a competitive and allosteric regulation for herbal ingredients. Drug-development could be based on the presented idea in this report.

Metformin downregulates miR223 expression in insulin-resistant 3T3L1 cells and human diabetic adipose tissue

AIMS AND DESIGNS

Metformin, an anti-diabetic drug, is the first line medication for the treatment of type 2 diabetes mellitus and some studies show its relationship with micro-RNAs. This study set up to determine the effect of metformin on miR223 expression and content of AKT/GLUT4 proteins in insulin resistant signaling in 3T3L1 cells and adipocyte of human diabetic patients.

MATERIALS AND METHODS

Subcutaneous adipose tissues were taken from newly diagnosed diabetic patients (HOMA-IR > 1.8), before and after three months treatment with 500 mg of metformin twice a day. Cellular homogenate was prepared and miR223 expression and AKT/GLUT4 protein expression were determined by quantitative real-time PCR and western blotting. The results were compared to insulin resistant 3T3L1 adipocytes that were treated with 10 mM Metformin.

RESULTS

MiR223 expression was significantly overexpressed both in insulin-resistant 3T3L1 adipocytes compared to non-insulin resistant adipocytes and in human diabetic adipose tissue, compared to non-diabetics (P value < 0.01). Metformin treatment downregulated miR223 expression in both adipocytes and human diabetic adipose tissue. In contrast the IRS/PI3-K/AKT pathway signaling components, Akt and GLUT4 increased in insulin-resistant 3T3L1 adipocytes and human diabetic adipose tissue after three months of metformin treatment.

CONCLUSIONS

Metformin reduced insulin resistance in adipocytes by reduction of miR223 expression and improving of IRS/Akt/GLUT4 signaling pathways. Plasma miR223 expression of human diabetic patients was reduced by metformin treatment. These results point to a novel mechanism of miR223 in insulin resistance.

Olive Leaf Polyphenols (OLPs) Stimulate GLUT4 Expression and Translocation in the Skeletal Muscle of Diabetic Rats

Skeletal muscles are high-insulin tissues responsible for disposing of glucose via the highly regulated process of facilitated glucose transporter 4 (GLUT4). Impaired insulin action in diabetes, as well as disorders of GLUT4 vesicle trafficking in the muscle, are involved in defects in insulin-stimulated GLUT4 translocation. Since the Rab GTPases are the main regulators of vesicular membrane transport in exo- and endo-cytosis, in the present work, we studied the effect of olive leaf polyphenols (OLPs) on Rab8A, Rab13, and Rab14 proteins of the rat soleus muscle in a model of streptozotocin (SZT)-induced diabetes (DM) in a dose-dependent manner. Glucose, cholesterol, and triglyceride levels were determined in the blood, morphological changes of the muscle tissue were captured by hematoxylin and eosin histological staining, and expression of GLUT4, Rab8A, Rab13, and Rab14 proteins were analyzed in the rat soleus muscle by the immunofluorescence staining and immunoblotting. OLPs significantly reduced blood glucose level in all treated groups. Furthermore, significantly reduced blood triglycerides were found in the groups with the lowest and highest OLPs treatment. The dynamics of activation of Rab8A, Rab13, and Rab14 was OLPs dose-dependent and more effective at higher OLP doses. Thus, these results indicate a beneficial role of phenolic compounds from the olive leaf in the regulation of glucose homeostasis in the skeletal muscle.

The Extracts of Cinnamon and Clove as Potential Biofungicides against Strawberry Grey Mould

Biofungicides from plants are a possibility for the biocontrol of fungal diseases, as chemical products may be harmful to the environment and humans. Strawberry is one of the many plants infected by grey mould (Botrytis cinerea), and innovative methods of biocontrol against B. cinerea are under investigation. Clove (Syzygium aromaticum L.) and cinnamon (Cinnamomum cassia L.) accumulate natural compounds, such as eugenol and cinnamaldehyde, which provide antimicrobial and antifungal properties; thus, extracts of these plants could be possibly used as biofungicides. During this study, the inhibition of B. cinerea by clove and cinnamon extracts was evaluated in vitro on Petri plates and detached strawberry leaves; additionally, the chemical composition of volatiles was identified. Clove extract consisted of 52.88% eugenol, and cinnamon consisted of 74.67% cinnamaldehyde. The efficacy of the extracts on detached strawberry leaves showed that 12 mL L⁻¹ concentration of clove extract was effective in suppressing the grey mould infection. Clove and cinnamon extracts showed an equal ability to inhibit B. cinerea on Petri plates. However, the results of the detached strawberry leaves assay showed that clove extract was more effective as a biocontrol product. Overall, clove extract expressed a high potential for application in biofungicides formulations.

Reduced obesity, diabetes, and steatosis upon cinnamon and grape pomace are associated with changes in gut microbiota and markers of gut barrier

Increasing evidence suggests that polyphenols have a significant potential in the prevention and treatment of risk factors associated with metabolic syndrome. The objective of this study was to assess the metabolic outcomes of two polyphenol-containing extracts from cinnamon bark (CBE) and grape pomace (GPE) on C57BL/6J mice fed a high-fat diet (HFD) for 8 wk. Both CBE and GPE were able to decrease fat mass gain and adipose tissue inflammation in mice fed a HFD without reducing food intake. This was associated with reduced liver steatosis and lower plasma nonesterified fatty acid levels. We also observed a beneficial effect on glucose homeostasis, as evidenced by an improved glucose tolerance and a lower insulin resistance index. These ameliorations of the overall metabolic profile were associated with a significant impact on the microbial composition, which was more profound for the GPE than for the CBE. At the genus level, Peptococcus were decreased in the CBE group. In the GPE-treated group, several key genera that have been previously found to be linked with HFD, metabolic effects, and gut barrier integrity were affected: we observed a decrease of Desulfovibrio, Lactococcus, whereas Allobaculum and Roseburia were increased. In addition, the expression of several antimicrobial peptides and tight junction proteins was increased in response to both CBE and GPE supplementation, indicating an improvement of the gut barrier function. Collectively, these data suggest that CBE and GPE can ameliorate the overall metabolic profile of mice on a high-fat diet, partly by acting on the gut microbiota.

Central alarin ameliorated insulin resistance of adipocytes in type 2 diabetic rats

Alarin, a regulatory peptide, belongs to the galanin family and plays the same regulatory roles as galanin in orexigenic activity and energy metabolism. Our previous studies had found that galanin might facilitate insulin sensitivity via activation of its central receptors. To date, little is known about whether central alarin may exert similar effects on insulin sensitivity. In order to investigate this, alarin and its specific antagonist, alarin 6-25Cys, were administered into the cerebral ventricles of type 2 diabetic rats (T2DR) to evaluate the changes in insulin resistance. The results indicated that central treatment with alarin significantly increased the body weight of animals, the 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose uptake, the plasma adiponectin levels, the glucose infusion rates in hyperinsulinemic-euglycemic clamp tests, the vesicle-associated membrane protein 2 as well as glucose transporter 4 (GLUT4 (SLC2A4)) protein and mRNA levels, and the ratios of GLUT4 contents in plasma membranes to total cell membranes in adipocytes, but reduced blood glucose and plasma retinol-binding protein 4 levels. These effects of alarin may be inhibited by pretreatment with alarin 6-25Cys. The above-mentioned results suggest that the central alarin projective system may facilitate insulin sensitivity and glucose uptake via the increase in GLUT4 content and GLUT4 translocation from intracellular pools to plasma membranes in T2DR.

Dietary stimulators of GLUT4 expression and translocation in skeletal muscle: a mini-review

Chronic insulin resistance can lead to type II diabetes mellitus, which is also directly influenced by an individual's genetics as well as their lifestyle. Under normal circumstances, insulin facilitates glucose uptake in skeletal muscle and adipose tissue by stimulating glucose transporter 4 (GLUT4) translocation and activity. GLUT4 activity is directly correlated with the ability to clear elevated blood glucose and insulin sensitivity. In diabetes, energy excess and prolonged hyperinsulinemia suppress muscle and adipose response to insulin, in part through reduced GLUT4 membrane levels. This work uniquely describes much of the experimental data demonstrating the effects of various dietary components on GLUT4 expression and translocation in skeletal muscle. These observations implicate several individual dietary chemicals as potential adjuvant therapies in the maintenance of diabetes and insulin resistance.