Glibenclamide: an old drug with a novel mechanism of action?

Strain-release driven reactivity of a chiral SuFEx reagent provides stereocontrolled access to sulfinamides, sulfonimidamides, and sulfoximines

Efforts aimed at enriching the chemical and structural diversity of small molecules have invigorated synthetic exploration in the last two decades. Spatially defined molecular functionality serves as the foundation to construct unique chemical space to further advance discovery science. The chiral SuFEx reagent t-BuSF provides a modular platform for the stereocontrolled bifunctionalization of sulfur. Here we report a third functional feature of t-BuSF enabled by carbamoyl torsional strain-release that further expands the S(IV) and S(VI) chemical space accessible as showcased in over seventy examples, multiple applications in medicinal chemistry, organocatalysis, and diversity-oriented synthesis. The methods presented herein allow for rapid asymmetric diversification around a stereodefined sulfur center with readily available building blocks, improving upon the current state-of-the-art for sulfinyl and sulfonimidoyl synthesis.

A simulation study on the antiarrhythmic mechanisms of established agents in myocardial ischemia and infarction

Patients with myocardial ischemia and infarction are at increased risk of arrhythmias, which in turn, can exacerbate the overall risk of mortality. Despite the observed reduction in recurrent arrhythmias through antiarrhythmic drug therapy, the precise mechanisms underlying their effectiveness in treating ischemic heart disease remain unclear. Moreover, there is a lack of specialized drugs designed explicitly for the treatment of myocardial ischemic arrhythmia. This study employs an electrophysiological simulation approach to investigate the potential antiarrhythmic effects and underlying mechanisms of various pharmacological agents in the context of ischemia and myocardial infarction (MI). Based on physiological experimental data, computational models are developed to simulate the effects of a series of pharmacological agents (amiodarone, telmisartan, E-4031, chromanol 293B, and glibenclamide) on cellular electrophysiology and utilized to further evaluate their antiarrhythmic effectiveness during ischemia. On 2D and 3D tissues with multiple pathological conditions, the simulation results indicate that the antiarrhythmic effect of glibenclamide is primarily attributed to the suppression of efflux of potassium ion to facilitate the restitution of [K+]o, as opposed to recovery of IKATP during myocardial ischemia. This discovery implies that, during acute cardiac ischemia, pro-arrhythmogenic alterations in cardiac tissue's excitability and conduction properties are more significantly influenced by electrophysiological changes in the depolarization rate, as opposed to variations in the action potential duration (APD). These findings offer specific insights into potentially effective targets for investigating ischemic arrhythmias, providing significant guidance for clinical interventions in acute coronary syndrome.

Evaluation of the Antidiabetic Activities of the Fruit of Parquetina nigrescens (Afzel.) Bullock and In Silico Identification of Its Antidiabetic Agent

The study investigated the antidiabetic potentials of the fruit extract of Parquetina nigrescens with the aim of justifying its folkloric antidiabetic usage in some part of Nigeria. Acute toxicity test of the plant extract was assessed using Lorke's method. Its antidiabetic activities were assayed in α-amylase, α-glucosidase, glucose, and streptozotocin-induced diabetic rats' models at various doses with acarbose and glibenclamide (5 mg/kg) as positive controls. Molecular docking studies were performed to identify the antidiabetic constituent of the extract and elucidate its possible mechanism of action. The estimated median lethal dose (LD50) of the extract was above 5000 mg/kg. In the α-amylase, α-glucosidase study, the extract elicited concentration-dependent activity similar to acarbose. In the glucose-induced hyperglycaemic model, 200 mg/kg of the extract was the most effective dose with comparable (P > .05) antihyperglycaemic activity to glibenclamide (5 mg kg) at 1 to 4 h. Also in the streptozotocin-induced diabetic rats model, 100 and 200 mg/kg of the extract gave comparable (P > 0.05) activity on days 4 to 14 that were significantly better than that of glibenclamide on days 4 to 7. The n-hexane and ethylacetate fractions of the extract, both at 200 mg/kg were the most active with comparable activity to glibenclamide at all time points. The molecular docking studies identified isorhoifolin as the best binder against alpha amylase with binding energy (-9.1 kcal/mol), alpha glucosidase (-9.4 kcal/mol), sodium-glucose cotransporter-2 (-9.5 kcal/mol), peroxisome proliferator activated receptor gamma (-10.3 kcal/mol), 11β-Hydroxysteroid dehydrogenase (-10.8 kcal/mol), and dipeptidyl peptidase IV (-9.4 kcal/mol). The results of the antidiabetic study of P nigrescence fruit extract justified its usage in ethnomedicne in diabetes management.

Mitochondrial Volume Regulation and Swelling Mechanisms in Cardiomyocytes

Mitochondrion, known as the "powerhouse" of the cell, regulates ion homeostasis, redox state, cell proliferation and differentiation, and lipid synthesis. The inner mitochondrial membrane (IMM) controls mitochondrial metabolism and function. It possesses high levels of proteins that account for ~70% of the membrane mass and are involved in the electron transport chain, oxidative phosphorylation, energy transfer, and ion transport, among others. The mitochondrial matrix volume plays a crucial role in IMM remodeling. Several ion transport mechanisms, particularly K+ and Ca2+, regulate matrix volume. Small increases in matrix volume through IMM alterations can activate mitochondrial respiration, whereas excessive swelling can impair the IMM topology and initiates mitochondria-mediated cell death. The opening of mitochondrial permeability transition pores, the well-characterized phenomenon with unknown molecular identity, in low- and high-conductance modes are involved in physiological and pathological increases of matrix volume. Despite extensive studies, the precise mechanisms underlying changes in matrix volume and IMM structural remodeling in response to energy and oxidative stressors remain unknown. This review summarizes and discusses previous studies on the mechanisms involved in regulating mitochondrial matrix volume, IMM remodeling, and the crosstalk between these processes.

Pharmacological Characterization of a Recombinant Mitochondrial ROMK2 Potassium Channel Expressed in Bacteria and Reconstituted in Planar Lipid Bilayers

In the inner mitochondrial membrane, several potassium channels that play a role in cell life and death have been identified. One of these channels is the ATP-regulated potassium channel (mitoK_ATP). The ROMK2 potassium channel is a potential molecular component of the mitoK_ATP channel. The current study aimed to investigate the pharmacological modulation of the activity of the ROMK2 potassium channel expressed in Escherichia coli bacteria. ROMK2 was solubilized in polymer nanodiscs and incorporated in planar lipid bilayers. The impact of known mitoK_ATP channel modulators on the activity of the ROMK2 was characterized. We found that the ROMK2 channel was activated by the mitoK_ATP channel opener diazoxide and blocked by mitoK_ATP inhibitors such as ATP/Mg²⁺, 5-hydroxydecanoic acid, and antidiabetic sulfonylurea glibenclamide. These results indicate that the ROMK2 potassium protein may be a pore-forming subunit of mitoK_ATP and that the impact of channel modulators is not related to the presence of accessory proteins.

NLRP3-mediated inflammation in cardio-oncology: sterile yet harmful

Despite significant advances and the continuous development of novel, effective therapies to treat a variety of malignancies, cancer therapy-induced cardiotoxicity has been identified as a prominent cause of morbidity and mortality, closely competing with secondary malignancies. This unfortunate limitation has prompted the inception of the field of cardio-oncology with its purpose to provide the necessary knowledge and key information on mechanisms that support the use of the most efficacious cancer therapy with minimal or no interruption while paying close attention to preventing cardiovascular related morbidity and mortality. Several mechanisms that contribute to cancer therapy-induced cardiotoxicity have been proposed and studied. These mainly involve mitochondrial dysfunction and reactive oxygen species-induced oxidative stress, lysosomal damage, impaired autophagy, cell senescence, DNA damage, and sterile inflammation with the formation and activation of the NLRP3 inflammasome. In this review, we focus on describing the principal mechanisms for different classes of cancer therapies that lead to cardiotoxicity involving the NLRP3 inflammasome. We also summarize current evidence of cardio-protection with inflammasome inhibitors in the context of heart disease in general, and further highlight the potential application of this evidence for clinical translation in at risk patients for the purpose of preventing cancer therapy associated cardiovascular morbidity and mortality.

Combined Gamma Conglutin and Lupanine Treatment Exhibits In Vivo an Enhanced Antidiabetic Effect by Modulating the Liver Gene Expression Profile

Previous studies have individually shown the antidiabetic potential of gamma conglutin (Cγ) and lupanine from lupins. Until now, the influence of combining both compounds and the effective dose of the combination have not been assessed. Moreover, the resulting gene expression profile from this novel combination remains to be explored. Therefore, we aimed to evaluate different dose combinations of Cγ and lupanine by the oral glucose tolerance test (OGTT) to identify the higher antidiabetic effect on a T2D rat model. Later, we administered the selected dose combination during a week. Lastly, we evaluated biochemical parameters and liver gene expression profile using DNA microarrays and bioinformatic analysis. We found that the combination of 28 mg/kg BW Cγ + 20 mg/kg BW lupanine significantly reduced glycemia and lipid levels. Moreover, this treatment positively influenced the expression of Pdk4, G6pc, Foxo1, Foxo3, Ppargc1a, Serpine1, Myc, Slc37a4, Irs2, and Igfbp1 genes. The biological processes associated with these genes are oxidative stress, apoptosis regulation, and glucose and fatty-acid homeostasis. For the first time, we report the beneficial in vivo effect of the combination of two functional lupin compounds. Nevertheless, further studies are needed to investigate the pharmacokinetics and pharmacodynamics of the Cγ + lupanine combined treatment.

Efficacy of Rytigynia senegalensis Blume on Free Radical Scavenging, Inhibition of α-Amylase and α-Glucosidase Activity, and Blood Glucose Level

Rytigynia senegalensis (Rubiaceae) is a plant used in African medicine for the treatment of diabetes. The aim of this study was to evaluate the in vitro antioxidant, enzyme inhibitory, and hypoglycemic effects of Rytigynia senegalensis extract (RSE). The contents of phenols, tannins, and flavonoids were determined by phytochemical screening. 2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenylpicrylhydrazyl (DPPH) were determined to evaluate the free radical scavenging capacity of the RSE. The inhibitory activity of α-amylase and α-glucosidase was evaluated in vitro using the α-amylase and α-glucosidase inhibition methods and in vivo using the sucrose and starch tolerance tests. The glucose tolerance test was performed on normal rats using doses of 50, 100, and 200 mg/kg of RSE. RSE contains total phenols (36.35 mg GAE/g of extract), flavonoids (11.91 mg QE/g of extract), and tannins (13.01 mg CE/g of extract). RSE exhibits significant radical scavenging activity on DPPH and ABTS radicals with an IC₅₀ of 17.51 and 21.89 μg/mL, respectively. RSE showed an inhibitory effect on the activity of α-amylase and α-glucosidase with an IC₅₀ of 308.93 and 354.13 μg/mL, respectively. RSE (100 and 200 mg/kg) caused a significant decrease in area under the curve and postprandial glycemia at 60, 90, and 120 min following the administration of starch or sucrose. Regarding the glucose tolerance test, RSE (100 and 200 mg/kg) significantly reduced postprandial hyperglycemia from the 90th min posttreatment. RSE lowered postprandial hyperglycemia and has antioxidant properties. These effects would be due to the presence of bioactive compounds in the RSE.

Targeting the NLRP3 inflammasome in cardiovascular diseases

The NACHT, leucine-rich repeat (LRR), and pyrin domain (PYD)-containing protein 3 (NLRP3) inflammasome is an intracellular sensing protein complex that plays a major role in innate immunity. Following tissue injury, activation of the NLRP3 inflammasome results in cytokine production, primarily interleukin(IL)-1β and IL-18, and, eventually, inflammatory cell death - pyroptosis. While a balanced inflammatory response favors damage resolution and tissue healing, excessive NLRP3 activation causes detrimental effects. A key involvement of the NLRP3 inflammasome has been reported across a wide range of cardiovascular diseases (CVDs). Several pharmacological agents selectively targeting the NLRP3 inflammasome system have been developed and tested in animals and early phase human studies with overall promising results. While the NLRP3 inhibitors are in clinical development, multiple randomized trials have demonstrated the safety and efficacy of IL-1 blockade in atherothrombosis, heart failure and recurrent pericarditis. Furthermore, the non-selective NLRP3 inhibitor colchicine has been recently shown to significantly reduce cardiovascular events in patients with chronic coronary disease. In this review, we will outline the mechanisms driving NLRP3 assembly and activation, and discuss the pathogenetic role of the NLRP3 inflammasome in CVDs, providing an overview of the current and future therapeutic approaches targeting the NLRP3 inflammasome.

Evaluation of in vitro antioxidant activity of okra mucilage and its antidiabetic and antihyperlipidemic effect in alloxan-induced diabetic mice

Okra (Abelmoschus esculentus) is a traditionally important vegetable herb used to treat numerous illnesses, including diabetes mellitus, in many rural parts of Bangladesh and the South Asian subcontinent. However, the scientific evidence for the aforementioned properties has not been adequately validated. Hence, the aim of this study was to explore the antidiabetic, antilipidemic activity of okra mucilage powder, and to compare its effectiveness with the isolated peel-seed of okra after mucilage extraction in Swiss albino mice. After extraction, both mucilage and peel-seed were made into powder. In addition, crude protein, mineral contents, and in vitro antioxidant activity of mucilage and peel-seed powder were assessed. After acute toxicity test, methanolic extracts of both powders were administered to alloxan-induced diabetic mice for 3 weeks. Blood glucose levels were assessed weekly. Finally, blood samples were collected on day 21 to estimate blood glucose level, total protein (TP), and lipid profile levels. Okra mucilage powder showed less amount of protein, calcium, magnesium, phosphorus, potassium, sodium, and iron compared with peel-seed powder. In terms of antioxidant activity, the IC50 value and total phenolic content were found higher in okra mucilage powder in contrast to peel-seed powder. However, total flavonoid content was higher in peel-seed powder than mucilage powder. Three-week administration of mucilage and peel-seed suspensions at a dose of 150 mg/kg and 200 mg/kg significantly (p < .05) reversed the abnormal changes of bodyweights, water consumption, feed consumption, and fasting blood glucose levels of diabetic subjects. Cholesterol, triglycerides, low-density lipoproteins, high-density lipoproteins, and total protein were found to be significantly (p < .05) improved after mucilage and peel-seed treatment. Thus, Okra can be recommended as a potential source of antidiabetic drug candidate for the effective management of diabetes mellitus and its complications.

Development, Characterization, Optimization, and In Vivo Evaluation of Methacrylic Acid-Ethyl Acrylate Copolymer Nanoparticles Loaded with Glibenclamide in Diabetic Rats for Oral Administration

The methacrylic acid–ethyl acrylate copolymer nanoparticles were prepared using the solvent displacement method. The independent variables were the drug/polymer ratio, surfactant concentration, Polioxyl 40 hydrogenated castor oil, the added water volume, time, and stirring speed, while size, PDI, zeta potential, and encapsulation efficiency were the response variables analyzed. A design of screening experiments was carried out to subsequently perform the optimization of the nanoparticle preparation process. The optimal formulation was characterized through the dependent variables size, PDI, zeta potential, encapsulation efficiency and drug release profiles. In vivo tests were performed in Wistar rats previously induced with diabetes by administration of streptozotocin. Once hyperglycemia was determined in rats, a suspension of nanoparticles loaded with glibenclamide was administered to them while the other group was administered with tablets of glibenclamide. The optimal nanoparticle formulation obtained a size of 18.98 +/− 9.14 nm with a PDI of 0.37085 +/− 0.014 and a zeta potential of −13.7125 +/− 1.82 mV; the encapsulation efficiency was of 44.5%. The in vivo model demonstrated a significant effect (p < 0.05) between the group administered with nanoparticles loaded with glibenclamide and the group administered with tablets compared to the group of untreated individuals.

Chenopodium quinoa Exhibits Antihyperglycemic Activity in Streptozotocin-Induced Diabetic Rats

AIMS

The aim of the study was to evaluate the antihyperglycemic effect of Chenopodium quinoa.

BACKGROUND

Chenopodium quinoa is a pseudocereal plant with several medicinal properties.

OBJECTIVE

The goal of this investigation was to determine the antihyperglycemic activity of Chenopodium quinoa in both normal and streptozotocin(STZ)-induced diabetic rats.

METHODS

In this study, the effect of the aqueous extract of Chenopodium quinoa seeds (AECQS) (60 mg/kg) on blood glucose levels was evaluated in both normal and diabetic rats after a single (6 hours) and repeated oral administration (7 days of treatment). The effect of this herb on glucose tolerance and lipid profile was also studied. Additionally, histopathological examination of liver was carried out using the Hematoxylin-Eosin method. Furthermore, the in vitro antioxidant activity as well as a preliminary phytochemical screening and quantification of some secondary metabolites (phenolic compounds, flavonoids and tannins) were performed according to standard methods.

RESULTS

AECQS produced a significant lowering effect on plasma glucose levels in STZ-induced diabetic rats. In addition, this extract exhibited a remarkable amelioration on hepatic histopathology in diabetic rats. In addition, the extract exerted a remarkable antioxidant activity which could be due to the presence of some compounds found in this herb.

CONCLUSION

In conclusion, this study demonstrates that the aqueous extract of Chenopodium quinoa seeds has a favorable effect in controlling diabetes mellitus.

Synthesis of a novel glibenclamide-pioglitazone hybrid compound and its effects on glucose homeostasis in normal and insulin-resistant rats

A new library of hybrid compounds that combine the functional parts of glibenclamide and pioglitazone was designed and developed. Compounds were screened for their antihyperglycemic effects on the glucose tolerance curve. This approach provided a single molecule that optimizes the pharmacological activities of two drugs used for the treatment of diabetes mellitus type 2 (DM2) and that have distinct biological activities, potentially minimizing the adverse effects of the original drugs. From a total of 15 compounds, 7 were evaluated in vivo; the compound 2; 4- [2- (2-phenyl-4-oxo-1,3-thiazolidin-3-yl) ethyl] benzene-1-sulfonamide (PTEBS) was selected to study its mechanism of action on glucose and lipid homeostasis in acute and chronic animal models related to DM2. PTEBS reduced glycemia and increased serum insulin in hyperglycemic rats, and elevated in vitro insulin production from isolated pancreatic islets. This compound increased the glycogen content in hepatic and muscular tissue. Moreover, PTEBS stimulated the uptake of glucose in soleus muscle through a signaling pathway similar to that of insulin, stimulating translocation and protein synthesis of glucose transporter 4 (GLUT4). PTEBS was effective in increasing insulin sensitivity in resistance rats by stimulating increased muscle glucose uptake, among other mechanisms. In addition, this compound reduced total triglycerides in a tolerance test to lipids and reduced advanced glycation end products (AGES), without altering lactate dehydrogenase (LDH) activity. Thus, we suggest that PTEBS may have similar effects to the respective prototypes, which may improve the therapeutic efficacy of these molecules and decrease adverse effects in the long-term.

The Effect of K ATP Channel Blocker Glibenclamide on CGRP-Induced Headache and Hemodynamic in Healthy Volunteers

BACKGROUND

Calcitonin gene-related peptide (CGRP) dilates cranial arteries and triggers headache. The CGRP signaling pathway is partly dependent on activation of ATP-sensitive potassium (K ATP ) channels. Here, we investigated the effect of the K ATP channel blocker glibenclamide on CGRP-induced headache and vascular changes in healthy volunteers.

METHODS

In a randomized, double-blind, placebo-controlled, cross-over study, 20 healthy volunteers aged 18-27 years were randomly allocated to receive an intravenous infusion of 1.5 μg/min CGRP after oral pretreatment with glibenclamide (glibenclamide-CGRP day) or placebo (placebo-CGRP day). The primary endpoints were the difference in incidence of headache and the difference in area under the curve (AUC) for headache intensity scores (0-14 h) between glibenclamide and placebo. The secondary endpoints were the difference in AUC for middle cerebral artery blood flow velocity (V MCA ), superficial temporal artery (STA) and radial artery (RA) diameter, facial flushing, heart rate (HR) and mean arterial blood pressure (MAP) (0-4 h) between glibenclamide and placebo.

RESULTS

We found no significant difference in the incidence of headache between glibenclamide-CGRP day (14/20, 70%) and placebo-CGRP day (19/20, 95%) (P = 0.06). The AUC for headache intensity, V MCA , STA, RA, facial skin blood flow, HR, and MAP did not differ between glibenclamide-CGRP day compared to placebo-CGRP day (P > 0.05).

CONCLUSION

Pretreatment with a non-selective K ATP channel inhibitor glibenclamide did not attenuate CGRP-induced headache and hemodynamic changes in healthy volunteers. We suggest that CGRP-induced responses could be mediated via activation of specific isoforms of sulfonylurea receptor subunits of K ATP channel.

Vascular Effects of Avocado Seed Glycosides during Diabetes-induced Endothelial Damage

Background and Objectives

The relationship between vascular damage and diabetes mellitus was exploited using avocado seed extracts. The purpose of the study was to understand the therapeutic relevance of glycosides compared to standard vascular and anti-diabetic drugs. Constituent Avocado Seed Glycosides (ASG) were analysed and administered to rats with Diabetes-Induced Vascular Damage (DIVD).

Methods

The rats were first administered with streptozotocin and screened after seven days for alterations in blood glucose, insulin, vascular cell adhesion molecule (VCAM-1), Von Willebrand factor (VWF), Renin-Angiotensin-Aldosterone System (RAS), eNOx, and endothelin-1 (ET-1). Only rats that satisfied these criteria were recruited and treated with either glibenclamide, met.su + losart, or 200 mg/kg body weight ASG for 28 days.

Results

There was an abundance of digitoxin (13.41 mg/100g), digoxin (17.98 mg/100g), avicularin (165.85 mg/100g), and hyperoside (282.51 mg/100g). ASG or met.su + losart exhibited slight modulatory properties on glucose homeostasis. Rats with DIVD showed elevated renin, angiotensin, VCAM-1 and Lp-PLA2 levels but slightly decreased with glibenclamide treatment and normalized with ASG or met.su + losart administration. All treatments normalized Hcy levels. DIVD caused the overproduction of CnT, LDH, Crt-K, LDL-c, TG, and TC and suppressed HDL-c but was completely normalized by the ASG. Water intake remained altered in treated rats.

Conclusion

The ASG had no relevant effect on glucose homeostasis during DIVD but showed significant vasoprotective properties.

Alotaibi A, Al-zharani M, Ziyyat A, Mekhfi H, Legssyer A, Aziz M, Bnouham M. Opuntia dillenii (Ker Gawl.) Haw., Seeds Oil Antidiabetic Potential Using In Vivo, In Vitro, In Situ, and Ex Vivo Approaches to Reveal Its Underlying Mechanism of Action

Opuntia dillenii Ker Gawl. is one of the medicinal plants used for the prevention and treatment of diabetes mellitus (DM) in Morocco. This study aims to investigate the antihyperglycemic effect of Opuntia dillenii seed oil (ODSO), its mechanism of action, and any hypoglycemic risk and toxic effects. The antihyperglycemic effect was assessed using the OGTT test in normal and streptozotocin (STZ)-diabetic rats. The mechanisms of action were explored by studying the effect of ODSO on the intestinal absorption of d-glucose using the intestinal in situ single-pass perfusion technique. An Ussing chamber was used to explore the effects of ODSO on intestinal sodium-glucose cotransporter 1 (SGLT1). Additionally, ODSO’s effect on carbohydrate degrading enzymes, pancreatic α-amylase, and intestinal α-glucosidase was evaluated in vitro and in vivo using STZ-diabetic rats. The acute toxicity test on mice was performed, along with a single-dose hypoglycemic effect test. The results showed that ODSO significantly attenuated the postprandial hyperglycemia in normal and STZ-diabetic rats. Indeed, ODSO significantly decreased the intestinal d-glucose absorption in situ. The ex vivo test (Ussing chamber) showed that the ODSO significantly blocks the SGLT1 (IC₅₀ = 60.24 µg/mL). Moreover, ODSO indu\ced a significant inhibition of intestinal α-glucosidase (IC₅₀ = 278 ± 0.01 µg/mL) and pancreatic α-amylase (IC₅₀ = 0.81 ± 0.09 mg/mL) in vitro. A significant decrease of postprandial hyperglycemia was observed in sucrose/starch-loaded normal and STZ-diabetic ODSO-treated rats. On the other hand, ODSO had no risk of hypoglycemia on the basal glucose levels in normal rats. Therefore, no toxic effect was observed in ODSO-treated mice up to 7 mL/kg. The results of this study suggest that ODSO could be suitable as an antidiabetic functional food.

NLRP3 Inflammasome Inhibitors in Cardiovascular Diseases

Virtually all types of cardiovascular diseases are associated with pathological activation of the innate immune system. The NACHT, leucine-rich repeat (LRR), and pyrin domain (PYD)-containing protein 3 (NLRP3) inflammasome is a protein complex that functions as a platform for rapid induction of the inflammatory response to infection or sterile injury. NLRP3 is an intracellular sensor that is sensitive to danger signals, such as ischemia and extracellular or intracellular alarmins during tissue injury. The NLRP3 inflammasome is regulated by the presence of damage-associated molecular patterns and initiates or amplifies inflammatory response through the production of interleukin-1β (IL-1β) and/or IL-18. NLRP3 activation regulates cell survival through the activity of caspase-1 and gasdermin-D. The development of NLRP3 inflammasome inhibitors has opened the possibility to targeting the deleterious effects of NLRP3. Here, we examine the scientific evidence supporting a role for NLRP3 and the effects of inhibitors in cardiovascular diseases.

Hydroalcoholic Extract of Solanum lycocarpum A. St. Hil. (Solanaceae) Leaves Improves Alloxan-Induced Diabetes Complications in Mice

BACKGROUND

Solanum lycocarpum is a medicinal plant widely-used in Brazil because its fruits have hypoglycemic activity. However, the fruits are restricted in some periods of the year.

OBJECTIVE

To evaluate the effects of hydroalcoholic extracts of S. lycocarpum leaves in alloxan-induced diabetic mice.

METHODS

Hydroalcoholic extract of S. lycocarpum was characterized by phytochemical and GC-MS analysis. The Antidiabetic activity was assessed following treatment for 22 days with S. lycocarpum extract at 125, 250, and 500 mg/kg. Bodyweight, water, and food intake, glycemia, biochemical parameters, anatomy-histopathology of the pancreas, liver and kidney, and expression of target genes were analyzed. In addition, oral acute toxicity was evaluated.

RESULTS

Animals treated showed a significant reduction (p < 0.05) in glycemia following a dose of 125 mg/kg. Food intake remained similar for all groups. Decreased polydipsia symptoms were observed after treatment with 250 (p < 0.001) and 500 mg/kg (p < 0.01) compared with diabetic control, although normal rates were observed when 125 mg/kg was administered. A protective effect was also observed in the pancreas, liver, and kidneys, through the regeneration of the islets. Hypoglycemic activity can be attributed to myo-inositol, which stimulates insulin secretion, associated with α-tocopherol, which prevents damage from oxidative stress and apoptosis of β-pancreatic cells by an increased Catalase (CAT) and Glutathione peroxidase 4 (GPX4) mRNA expression. The toxicological test demonstrated safe oral use of the extract under the present conditions.

CONCLUSION

Hydroalcoholic extract of S. lycocarpum promotes the regulation of diabetes in the case of moderate glycemic levels, by decreasing glycemia and exerting protective effects on the islets.

Embryonic cardioprotection by hydrogen sulphide: studies of isolated cardiac function and ischaemia-reperfusion injury in the chicken embryo

KEY POINTS

In mammals, pregnancy complications can trigger an embryonic or fetal origin of cardiac dysfunction. However, underlying mechanisms remain uncertain because the partial contributions of the challenge on the mother, placenta or offspring are difficult to disentangle. The avian embryo permits isolation of the direct effects of suboptimal conditions during development on the cardiac function of the offspring, independent of additional effects on the mother and/or the placenta. Therefore, the objectives of this work were to adapt the isolated Langendorff technique using the chicken embryo to study the physiology of the developing heart. Here, we introduce a novel technique and show the utility of the technique for exploring cardioprotective roles of H₂ S in the chicken embryo heart. This work lays the foundation for studying the direct effects of H₂ S therapy on the embryonic heart independent of effects on the mother and the placenta in adverse development.

ABSTRACT

This study adapted the isolated Langendorff preparation to study the chicken embryo heart in response to ischaemia-reperfusion (IR) injury. The utility of the technique was tested by investigating cardioprotective effects of hydrogen sulphide (H₂ S) and underlying mechanisms. Embryonic hearts (19 out of 21 days of incubation) mounted on a Langendorff preparation were exposed to IR (30 min ischaemia) after 4 treatments administered randomly, all as a 1 mm bolus, into the perfusate: saline vehicle (control); sodium hydrogen sulphide (NaHS); NaHS plus glibenclamide, an antagonist of K_ATP opening (NaHS Glib), and Glib alone (Glib). Relative to controls, NaHS treatment improved cardiac function after ischaemia (mean ± SD for area under the curve, AUC, for left ventricular developed pressure, LVDP: 1767.3 ± 929.5 vs. 492.7 ± 308.1; myocardial contractility, dP/dt_max : 2748.9 ± 1514.9 vs. 763.7 ± 433.1) and decreased infarct size (22.7 ± 8.0 vs. 43.9 ± 4.2%) and cardiac damage (% change in creatinine kinase, 49.3 ± 41.3 vs. 214.6 ± 155.1; all P < 0.05). Beneficial effects of NaHS were blocked by Glib. Glib alone had no effects. NaHS increased coronary flow rate (CFR) during baseline (mean ± SD for AUC: 134.3 ± 91.6 vs. 92.2 ± 35.8) and post IR (1467 ± 529.5 vs. 748.0 ± 222.1; both P < 0.05). However, this effect was not prevented by Glib. Therefore, the chicken embryo heart is amenable for study via the Langendorff preparation under basal conditions and during IR. The data show that H₂ S confers embryonic cardiac protection via opening of myocardial K_ATP channels and not via increasing CFR. H₂ S may prove a useful therapeutic agent to protect the human fetal heart against IR injury, as may occur in complicated labour.

The Spasmolytic Effect of Astragalus Sarcocolla on the Intestinal Smooth Muscles of Rabbit In Vitro: Potassium Channel Opening

Introduction

Astragalus species have been widely used in Chinese herbal medicine to treat gastrointestinal and inflammatory disorders. This study was conducted to evaluate the efficacy of Astragalus sarcocolla (ASE) and to rationalize its medicinal use as an antispasmodic drug for the treatment of spasmodic gastrointestinal and inflammatory disorders associated with increased intestinal motility.

Methods

The ethanolic extract of ASE was studied to examine its antispasmodic effect on the isolated rabbit ileum preparations, and the contractions were recorded on PowerLab (ADInstruments, Sydney, Australia).

Results

ASE was able to inhibit spontaneous ileum contractions. It also completely inhibited K⁺ (25 mM)-induced contractions but was unable to inhibit high K⁺ (80 mM)-induced sustained contractions. Pretreatment of the tissue with glibenclamide, a potassium channel blocker, caused a rightward shift of the dose-response curve when stimulated with K⁺ (25 mM) in the presence of an increasing concentration of the extract. Verapamil at very low doses inhibited both the 25 mM and 80 mM K⁺-induced contractions.

Conclusion

The results of our study demonstrated the spasmolytic activity of ASE with the potential mechanism of activation of K⁺ATP, which provides a strong basis for its medicinal use in motility and inflammatory disorders of the intestine.

KATP channels modulate cerebral blood flow and oxygen delivery during isocapnic hypoxia in humans

KEY POINTS

ATP-sensitive K⁺ (K_ATP ) channels mediate hypoxia-induced cerebral vasodilatation and hyperperfusion in animals. We tested whether K_ATP channels blockade affects the increase in human cerebral blood flow (CBF) and the maintenance of oxygen delivery (CDO₂ ) during hypoxia. Hypoxia-induced increases in the anterior circulation and total cerebral perfusion were attenuated under K_ATP channels blockade affecting the relative changes of brain oxygen delivery. Therefore, in humans, K_ATP channels activation modulates the vascular tone in the anterior circulation of the brain, contributing to CBF and CDO₂ responses to hypoxia.

ABSTRACT

ATP-sensitive K⁺ (K_ATP ) channels mediate hypoxia-induced cerebral vasodilatation and hyperperfusion in animals. We tested whether K_ATP channels blockade affects the increase in cerebral blood flow (CBF) and the maintenance of oxygen delivery (CDO₂ ) during hypoxia in humans. Nine healthy men were exposed to 5-min trials of normoxia and isocapnic hypoxia (IHX, 10% O₂ ) before (BGB) and 3 h after glibenclamide ingestion (AGB). Mean arterial pressure (MAP), arterial saturation ( S a O 2 ), partial pressure of oxygen ( P a O 2 ) and carbon dioxide ( P aC O 2 ), internal carotid artery blood flow (ICABF), vertebral artery blood flow (VABF), total (t)CBF (Doppler ultrasound) and CDO₂ were quantified during the trials. IHX provoked similar reductions in S a O 2 and P a O 2 , while MAP was not affected by oxygen desaturation or K_ATP blockade. A smaller increase in ICABF (ΔBGB: 36 ± 23 vs. ΔAGB 11 ± 18%, p = 0.019) but not in VABF (∆BGB 26 ± 21 vs. ∆AGB 27 ± 27%, p = 0.893) was observed during the hypoxic trial under K_ATP channels blockade. Thus, IHX-induced increases in tCBF (∆BGB 32 ± 19 vs. ∆AGB 14 ± 13%, p = 0.012) and CDO₂ relative changes (∆BGB 7 ± 13 vs. ∆AGB -6 ± 14%, p = 0.048) were attenuated during the AGB hypoxic trial. In a separate protocol, 6 healthy men (5 from protocol 1) underwent a 5-min exposure to normoxia and IHX before and 3 h after placebo (5 mg of cornstarch) ingestion. IHX reduced S a O 2 and P a O 2 , but placebo did not affect the ICABF, VABF, tCBF, or CDO₂ responses. Therefore, in humans, K_ATP channels activation modulates vascular tone in the anterior rather than the posterior circulation of the brain, contributing to tCBF and CDO₂ responses to hypoxia.

Aqueous extract from Mangifera indica Linn. (Anacardiaceae) leaves exerts long-term hypoglycemic effect, increases insulin sensitivity and plasma insulin levels on diabetic Wistar rats

BACKGROUND

Diabetes mellitus is one of the most common todays public health problems. According to a survey by the World Health Organization, this metabolic disorder has reached global epidemic proportions, with a worldwide prevalence of 8.5% in the adult population.

OBJECTIVES

The present study aimed to investigate the hypoglycemic effect of aqueous extract of Mangifera indica (EAMI) leaves in streptozotocin-induced diabetic rats.

METHODS

Sixty male rats were divided into 2 groups: Normoglycemic and Diabetic. Each group was subdivided into negative control, glibenclamide 3 or 10 mg/kg, EAMI 125, 250, 500, and 1000 mg/kg. Intraperitoneal injection of streptozotocin 100 mg/kg was used to DM induction. The hypoglycemic response was assessed acutely after two and four weeks of treatment. After a 6-hour fasting period, the fasting blood glucose of animals was verified, and 2.5 g/kg glucose solution was orally administered. The insulin tolerance test and plasma insulin levels assessment were performed in the morning after fasting of 12 to 14 hours.

RESULTS AND CONCLUSION

The chemical analysis of EAMI showed high levels of phenolic compounds. There was no significant difference in fasting blood glucose between normoglycemic and diabetic groups, and that EAMI did not have an acute effect on diabetes. After two and four weeks of treatment, the extract significantly reduced blood glucose levels, exceeding glibenclamide effects. EAMI was effective in maintaining the long-term hypoglycemic effect, as well as, significantly increased the sensitivity of diabetic animals to insulin and the plasma insulin level.

Calcium Signaling in ß-cell Physiology and Pathology: A Revisit

Pancreatic beta (β) cell dysfunction results in compromised insulin release and, thus, failed regulation of blood glucose levels. This forms the backbone of the development of diabetes mellitus (DM), a disease that affects a significant portion of the global adult population. Physiological calcium (Ca²⁺) signaling has been found to be vital for the proper insulin-releasing function of β-cells. Calcium dysregulation events can have a dramatic effect on the proper functioning of the pancreatic β-cells. The current review discusses the role of calcium signaling in health and disease in pancreatic β-cells and provides an in-depth look into the potential role of alterations in β-cell Ca²⁺ homeostasis and signaling in the development of diabetes and highlights recent work that introduced the current theories on the connection between calcium and the onset of diabetes.

Fournier's Gangrene in a Patient with Type 2 Diabetes Mellitus Treated with Empagliflozin: A Case Report

Sodium-glucose cotransporter-2 (SGLT2) inhibitors have been reported as possibly associated with Fournier’s gangrene (FG). This case report describes a 34-year-old Japanese man who was diagnosed with FG after the administration of empagliflozin for type 2 diabetes mellitus (T2DM). He presented with pain and swelling in the perineum and groin 142 days after initiating empagliflozin. The clinical features, laboratory data, and computed tomographic findings were consistent with FG. Surgical drainage and debridement of necrotic tissues were performed immediately after admission to our hospital. The patient had no complications of diabetes before the onset of FG. Glycemic management was good at the time of FG onset. This case suggests a possible association between empagliflozin and FG. We report a case of FG in a patient during a period of good glycemic management following treatment with empagliflozin. We recommend further awareness of this relationship and suggest the need for additional research.

Optimization of Hyperglycemic Induction in Zebrafish and Evaluation of Its Blood Glucose Level and Metabolite Fingerprint Treated with Psychotria malayana Jack Leaf Extract

A standard protocol to develop type 1 diabetes in zebrafish is still uncertain due to unpredictable factors. In this study, an optimized protocol was developed and used to evaluate the anti-diabetic activity of Psychotria malayana leaf. The aims of this study were to develop a type 1 diabetic adult zebrafish model and to evaluate the anti-diabetic activity of the plant extract on the developed model. The ability of streptozotocin and alloxan at a different dose to elevate the blood glucose levels in zebrafish was evaluated. While the anti-diabetic activity of P. malayana aqueous extract was evaluated through analysis of blood glucose and LC-MS analysis fingerprinting. The results indicated that a single intraperitoneal injection of 300 mg/kg alloxan was the optimal dose to elevate the fasting blood glucose in zebrafish. Furthermore, the plant extract at 1, 2, and 3 g/kg significantly reduced blood glucose levels in the diabetic zebrafish. In addition, LC-MS-based fingerprinting indicated that 3 g/kg plant extract more effective than other doses. Phytosterols, sugar alcohols, sugar acid, free fatty acids, cyclitols, phenolics, and alkaloid were detected in the extract using GC-MS. In conclusion, P. malayana leaf aqueous extract showed anti-diabetic activity on the developed type 1 diabetic zebrafish model.

Cyclodextrin-grafted poly(anhydride) nanoparticles for oral glibenclamide administration. In vivo evaluation using C. elegans

The aim of this work was to prepare and evaluate cyclodextrins-modified poly(anhydride) nanoparticles to enhance the oral administration of glibenclamide. A conjugate polymer was synthesized by incorporating hydroxypropyl-β-cyclodextrin to the backbone of poly(methylvinyl ether-co-maleic anhydride) via Steglich reaction. The degree of substitution of anhydride rings by cyclodextrins molecules was calculated to be 4.9% using H-NMR spectroscopy. A central composite design of experiments was used to optimize the preparative process. Under the optimal conditions, nanoparticles displayed a size of about 170 nm, a surface charge of -47 mV and a drug loading of 69 µg GB/mg. X-ray diffraction studies confirmed the loss of the crystalline structure of GB due to its dispersion into the nanoparticles, either included into cyclodextrin cavities or entrapped in the polymer chains. Glibenclamide was mainly release by Fickian-diffusion in simulated intestinal fluid. GB-loaded nanoparticles produced a hypolipidemic effect over C. elegans N2 wild-type and daf-2 mutant. The action mechanism included daf-2 and daf-28 genes, both implicated in the insulin signaling pathway of C. elegans. In summary, the covalent linkage of cyclodextrin to the poly(anhydride) backbone could be an interesting strategy to prepare nanoparticles for the oral administration of glibenclamide.

Validation of the antihyperglycaemic and hepatoprotective activity of the flavonoid rich fraction of Brachychiton rupestris using in vivo experimental models and molecular modelling

Oxidative stress leads to many disorders as diabetes mellitus and liver diseases. This study evaluates the antihyperglycemic and hepatoprotective activities of Brachychiton rupestris (Malvaceae). The antihyperglycemic activity of the total methanol extract of B. rupestris leaves (BRT) and its ethyl acetate fraction (BRE) was evaluated using streptozotocin induced diabetic rats. The hepatoprotective activity was assessed using carbon-tetrachloride induced hepatotoxicity. Oral administration of 50 mg/kg b.wt (body weight) of BRT and BRE to Streptozotocin -diabetic rats caused a notable decrease in serum glucose by 39.38 and 42.09% with 35.62 and 15.44% increase in serum insulin, respectively, compared with Streptozotocin-diabetic rats. Oral administration of BRT and BRE to carbon-tetrachloride -treated rats (50 mg/kg b.wt) resulted in reduction in serum aspartate transaminase (AST) (28.88 and 27.2%, respectively) and alanine transaminase (ALT) (8 and 13.56%) levels, respectively. They also ameliorated oxidative stress in both models as evidenced from oxidative stress markers. Liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) analysis of the most active fraction (BRE) identified nine compounds including flavonoids and phenolic acids. Molecular modelling of the identified compounds was performed on human pancreatic α-amylase (HPA) and human α-glucosidase (HAG) using Discovery Studio 2.5. Quercetin-3-O-(6″-O-α-l-rhamnopyranosyl)-β-D-glucoside showed the greatest affinity towards both HPA and HAG. Thus, this study provided scientific evidence on the antihyperglycemic and hepatoprotective activities of Brachychiton rupestris.

Impact of oral hypoglycemic agents on mortality among diabetic patients with non-muscle-invasive bladder cancer: A populationbased analysis

INTRODUCTION

Non-muscle-invasive bladder cancer (NMIBC) accounts for 75-85% of all urothelial bladder cancers (UBC). Many UBC patients are also afflicted by diabetes mellitus (DM). It has been postulated that several oral hypoglycemic agents could impact disease-specific survival (DSS), but the data are sparse among NMIBC patients. Our primary objective was to evaluate the impact of metformin on DSS and overall survival (OS) in NMIBC patients.

METHODS

This is a retrospective, population-based study that used linked administrative databases to identify diabetic patients ≥66 years who were subsequently diagnosed with NMIBC in Ontario between 1992 and 2012. Cumulative use of metformin and other hypoglycemic agent were calculated before and after NMIBC diagnosis. DSS and OS were estimated using multivariable competing risk and Cox proportional hazards models, respectively.

RESULTS

A total of 1742 subjects were included in the study. After a median followup of 5.2 years, 1122 (64%) had died, including 247 (15%) deaths as a result of UBC. On multivariable analysis, cumulative duration of metformin use after NMIBC diagnosis did not appear to impact DSS (hazard ratio [HR] 1.1; 95% confidence interval [CI] 0.92-1.2), whereas glyburide use appeared to have a detrimental effect (HR 1.17; 95% CI 1.02-1.3). None of the other hypoglycemic agents had an impact on OS.

CONCLUSIONS

In this large, population-based study, we have provided further evidence that metformin use does not significantly impact DSS among diabetic patients diagnosed with NMIBC. However, our findings demonstrate that glyburide use inversely affects DSS. The detrimental effect of glyburide on DSS will require further validation.

Coencapsulation of cyclodextrins into poly(anhydride) nanoparticles to improve the oral administration of glibenclamide. A screening on C. elegans

This work describes the feasibility of poly(anhydride) nanoparticles as carriers for the oral administration of glibenclamide (GB) as well as the in vivo evaluation of their hypolipidemic effect in a C. elegans model. For this purpose, and in order to increase the GB payload, the drug was encapsulated in nanoparticles in presence of cyclodextrins (either βCD or HPβCD). The optimized nanoparticles displayed a size of about 220 nm and a negative zeta potential (-40 mV), with a drug loading up to 52 μg/mg. Small-angle neutron scattering studies suggested an internal fractal-like structure, based on the repetition of spherical blocks of polymeric units (about 5 nm) grouped to form the nanoparticle. X-ray diffraction study confirmed the absence of crystalline GB molecules due to its dispersion into the nanoparticles, either entrapped in the polymer chains and/or included into cyclodextrin cavities. GB-loaded nanoparticles induced a significant reduction in the fat content of C. elegans. This hypolipidemic effect was slightly higher for the nanoparticles prepared with coencapsulated HPβCD (8.2%) than for those prepared with βCD (7.9%) or in the absence of cyclodextrins (7.0%). In summary, the coencapsulation of cyclodextrins into poly(anhydride) nanoparticles could be an interesting strategy to develop new oral formulations of glibenclamide.

Murraya paniculata (L.) (Orange Jasmine): Potential Nutraceuticals with Ameliorative Effect in Alloxan-Induced Diabetic Rats

Orange jasmine, Murraya paniculata (Rutaceae), is a plant from India widely used in folk medicine as antinociceptive, antiinflammatory, and antioxidant. Although oral hypoglycemic agents and insulin are the mainstays of treatment of diabetes mellitus (DM), there is a significant demand for new natural products to reduce the development of diabetic complications. Alloxan-induced diabetic rats were treated for 60 days with a hydroalcoholic extract of M. paniculata (MPE), at doses of 100, 200, and 400 mg/kg. MPE decreased glycemia and also cholesterol and triglyceride levels, starting 1 week after treatments, as compared with the same group before treatments. Glucose values were reduced toward normality after 1 week of treatment. MPE hypoglycemic effects were potentiated by glibenclamide and metformin. MPE also decreased fructosamine and glycated hemoglobin values. MPE reduced diabetes-induced morphological alterations of the kidney, pancreas, and liver. MPE acts similarly to glibenclamide and metformin, and its glucose-lowering action is partly a consequence of ATP-sensitive K⁺ channel inhibition. MPE may be a potential therapeutic alternative for the treatment of diabetes and its complications. Copyright © 2017 John Wiley & Sons, Ltd.

Investigation into Hypoglycemic, Antihyperlipidemic, and Renoprotective Potentials of Dennettia tripetala (Pepper Fruit) Seed in a Rat Model of Diabetes

This study investigated the hypoglycemic, antihyperlipidemic, and renoprotective potentials of Dennettia tripetala (DT) in a rat model of diabetes. The hypoglycemic activity in crude methanol seed extract of DT (CMEDT) and methanol seed fraction of DT (MFDT) measured by glucose oxidase method was increased by 47.37% and 28.72%, respectively, after 8 hours of administration. After 10 days of treatment, CMEDT and MFDT gave a good glycemic control with the highest percentage reduction of 75.82% and 71.34% in glucose level, respectively, which is closely compared with 79.91% in glibenclamide. Using the enzymatic assay and Friedewald's equation, there was a significant reduction in serum level of total cholesterol (TC), triglyceride (TG), very-low-density lipoprotein (VLDL), and low-density lipoprotein (LDL) and a significant increase in high-density lipoprotein (HDL) (p < 0.05) following treatment with CMEDT and MFDT, when compared with the untreated group, although results varied in dosed groups, with high dose of MFDT showing a better lipid-lowering activity. High dose of MFDT improved lipid metabolism and increased percentage protection against atherogenesis by 44%. However, neither CMEDT nor MFDT ameliorated the renal biochemical alteration in urea and creatinine. Thus, the study demonstrates hypoglycemic and antihyperlipidemic potentials of DT seed in diabetes.

Cryptolepine, an indoloquinoline alkaloid, in the management of diabetes mellitus and its associated complications

Background:

Effective long-term management is the key to treatment of diabetes mellitus (DM) and its complications.

Aim:

To ascertain the ability of cryptolepine (CRP) in managing DM and some associated complications.

Materials and Methods:

Changes in fasting blood sugar (FBS), body weight, response to thermally-induced pain, and semen quality were assessed in normal and alloxan-induced diabetic rats treated with CRP (10, 30, or 100 mg/kg), glibenclamide (10 mg/kg), or normal saline (2 ml/kg) per os. Hematological profile, liver and kidney function tests, lipid profile, as well as liver, kidney, and pancreas histopathological examinations were also conducted to establish possible effects of CRP treatment.

Results:

CRP treatment reduced (P ≤ 0.001) FBS and body weight, inhibited (P ≤ 0.05 - 0.001) the latency to tail flick or withdrawal from pain stimulus. It did not alter (P > 0.05): Hematological parameters, elevated (P ≤ 0.05 - 0.001) plasma aspartate transaminase, alanine transaminase, and gamma-glutamyl transferase, reduced (P ≤ 0.01) plasma urea, and elevated (P ≤ 0.001) plasma creatinine associated with DM. CRP, however, reversed (P ≤ 0.05 - 0.001) DM-associated elevation (P ≤ 0.05 - 0.001) of plasma cholesterol, triglycerides, and low-density lipoproteins, and the reduction in high-density lipoproteins. CRP (10-30 mg/kg) showed dose-dependent regeneration of β-islet cells but could not repair degenerated liver and kidney tissue. CRP worsens dose-dependently (P ≤ 0.001) reduced sperm quality associated with DM.

Conclusion:

CRP abolishes hyperglycemia, weight loss, cold allodynia, neuropathic pain, and hyperlipidemia as well as pancreatic β-islet cell damage associated with DM. It, however, does not improve liver and kidney damage and lowered semen quality.

Investigational agents for treatment of traumatic brain injury

INTRODUCTION

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. To date, there are no pharmacologic agents proven to improve outcomes from TBI because all the Phase III clinical trials in TBI have failed. Thus, there is a compelling need to develop treatments for TBI.

AREAS COVERED

The following article provides an overview of select cell-based and pharmacological therapies under early development for the treatment of TBI. These therapies seek to enhance cognitive and neurological functional recovery through neuroprotective and neurorestorative strategies.

EXPERT OPINION

TBI elicits both complex degenerative and regenerative tissue responses in the brain. TBI can lead to cognitive, behavioral, and motor deficits. Although numerous promising neuroprotective treatment options have emerged from preclinical studies that mainly target the lesion, translation of preclinical effective neuroprotective drugs to clinical trials has proven challenging. Accumulating evidence indicates that the mammalian brain has a significant, albeit limited, capacity for both structural and functional plasticity, as well as regeneration essential for spontaneous functional recovery after injury. A new therapeutic approach is to stimulate neurovascular remodeling by enhancing angiogenesis, neurogenesis, oligodendrogenesis, and axonal sprouting, which in concert, may improve neurological functional recovery after TBI.

Metformin promotes irisin release from murine skeletal muscle independently of AMP-activated protein kinase activation

AIM

Irisin, a novel myocyte-secreted hormone mediating beneficial effects of exercise on metabolism, is supposed to be an ideal therapeutic target for metabolic disorders such as obesity and diabetes. Here, we investigated the potential effects of metformin and glibenclamide, two antidiabetic medicines, on irisin release in mouse.

METHODS

Wild-type and diabetic obese db/db mice were administrated with metformin and glibenclamide for 2 weeks, and cultured C2C12 myotubes were treated by metformin. Expression of irisin precursor FNDC5 was measured and blood irisin concentration was detected. AMP-activated protein kinase (AMPK) was blocked by chemical inhibitor compound C or knocking down with specific siRNA.

RESULTS

The mRNA and protein expression of FNDC5 in skeletal muscle and blood irisin concentrations were lower in diabetic db/db mice than those in wild-type mice. Metformin and glibenclamide decreased blood glucose in db/db mice. Metformin, but not glibenclamide, increased intramuscular FNDC5 mRNA/protein expression and blood irisin levels. Additionally, the reductions of blood glucose and body weight in metformin-treated db/db mice were positively associated with blood irisin concentrations. In C2C12 myotubes, metformin upregulated intracellular FDNC5 mRNA/protein expression and promoted irisin release. Although metformin activated AMPK signalling in skeletal muscle cells, disrupting of AMPK signalling by chemical inhibitor or siRNA-mediated knockdown did not abolish the promoting effect of metformin on irisin release.

CONCLUSION

Metformin promotes irisin release from murine skeletal muscle into blood, independently of AMPK pathway activation. Our results suggest that stimulation of irisin may be a novel molecular mechanism of metformin which is widely used for treatment of metabolic disorders.

Alteration of glucose lowering effect of glibenclamide on single and multiple treatments with fenofibrate in experimental rats and rabbit models

Objective:

Diabetes mellitus is a syndrome of multiple etiologies. Both type 1 and type 2 diabetes lead to multiple abnormalities of lipid and lipoprotein metabolism. The aim of this investigation was to study the influence of fenofibrate on the blood glucose lowering effect of glibenclamide.

Materials and Methods:

Glibenclamide (0.45, 0.23 mg/kg) and fenofibrate (18.1, 9.38 mg/kg) was treated to normal, diabetic rats, and normal rabbits. Blood samples were collected at various time intervals and were analyzed for blood glucose levels using a glucometer.

Results:

Co-administration of fenofibrate with glibenclamide significantly elevated the blood glucose reduction exhibited by glibenclamide.

Conclusion:

The results obtained from single and multiple dose treatments clearly demonstrated the existence of drug-drug interaction at the dose tested in animal models. Hence, this investigation would serve as a preclinical evidence for the effect of fenofibrate on the therapeutic efficacy of glibenclamide.

Pentoxifylline decreases glycemia levels and TNF-alpha, iNOS and COX-2 expressions in diabetic rat pancreas

Pentoxifylline (PTX), a methyl xanthine derivative, is a phosphodiesterase inhibitor with anti-inflammatory and renoprotective effects in diabetic patients, among other properties. We studied PTX actions and mechanisms in reducing blood biochemical parameters, in diabetic rats. For diabetes induction, alloxan was intravenously administered to male Wistar rats. One group was left untreated and the other ones treated with PTX (25, 50 and 100 mg/kg), glibenclamide or metformin, as references. Forty-eight hours later and after 1-week to 3-month treatments, blood was collected for determination of glycemia, triglycerides, cholesterol, transaminases, fructosamine and glycated hemoglobin. Afterwards, the animals were euthanized and pancreas, liver and kidney processed for histological analyses and immunohistochemistry assays for TNF-alpha, iNOS and COX-2. The results showed that PTX decreased glycemia and also triglyceride levels, starting 1 week after treatments, as compared to the same group before treatments. Glycemia values were brought towards normality, after 1-month treatment. PTX hypoglycemic effects were potentiated by glibenclamide but not by metformin. It also decreased fructosamine and glycated hemoglobin. Some histological and immunohistochemical alterations for TNF-alpha, iNOS and COX-2 in the diabetic pancreas were also reversed by PTX. We conclude that PTX acts similarly to glibenclamide, and its hypoglycemic actions are, partly, a consequence of ATP-sensitive K(+) channels inhibition. In addition, by its anti-inflammatory and antioxidant properties, PTX may be a therapeutic alternative for the treatment of diabetes and its complications.

Evaluation of ethnomedical claim III: anti-hyperglycemic activities of Gongronema latifolium root and stem

BACKGROUND

The insulinotropic activity of the combined root and stem of Gongronema latifolium (Asclepiadaceae) was evaluated to justify its African ethnomedicinal use in the management of diabetes.

METHODS

A methanolic extract and its chromatographic fractions (A1 -A6 ) were tested for glucose-reducing and in vitro insulin-stimulating abilities using glucose-loaded rats and INS-1 cells, respectively. In vivo insulin-releasing activities for the significantly (P<0.05) active antihyperglycemic A5 and A6 and in vitro insulinotropic activity of the C1 fraction and its isolated constituents were also similarly determined.

RESULTS

The extract (100 mg/kg) had higher in vivo antihyperglycemic activity than the individual A1 -A6 , indicating a synergistic effect of the plant constituents. Higher in vivo insulin release in response to A5 (100 mg/kg) than A6 , agreed with their in vivo antihyperglycemic activities and confirmed insulin release as a mechanism of action of the plant. Compared with 5.6 mmol/L glucose (negative control), the extract and the A3 , A6 , and C1 (all at 100.0 μg/mL) elicited significantly higher in vitro insulin release that was similar to that of glibenclamide (1.0 μg/mL; P>0.05). Fraction C1 yielded a 1:1 mixture of α-amyrin and β-amyrin cinnamates (1a:1b), lupenyl cinnamate (2), lupenyl acetate (3), and two unidentified triterpenoids, Y and Z. The 1a:1b mixture (100.0 μg/mL) demonstrated the highest insulinotropic activity that was comparable (P>0.05) to that of glibenclamide (1.0 μg/mL).

CONCLUSIONS

The results confirm pancreatic activity as a mechanism underlying the antidiabetic action of G. latifolium and justify its ethnomedical use.

Synergistic interaction between metformin and sulfonylureas on diclofenac-induced antinociception measured using the formalin test in rats

BACKGROUND

There is evidence that biguanides and sulfonylureas block diclofenac-induced antinociception (DIA) in rat models. However, little is known about the interaction between these hypoglycemics with respect to DIA.

OBJECTIVE

To determine whether metformin-sulfonylurea combinations affect DIA during the formalin test.

METHODS

Rats received the appropriate vehicle or diclofenac before 1% formaldehyde was injected into the paw. Rats were also pretreated with vehicle, glibenclamide, glipizide, metformin or glibenclamide⁄metformin and glipizide⁄metformin combinations before the diclofenac and formaldehyde injections, and the effect on antinociception was assessed. Isobolograms of the combinations were constructed to test for a synergistic interaction.

RESULTS

Systemic injection of diclofenac resulted in antinociception during the second phase of the test. Systemic pretreatment with the combinations of glibenclamide (0.56 mg⁄kg to 10 mg⁄kg)⁄metformin (10 mg⁄kg to 180 mg⁄kg) and glipizide (0.56 mg⁄kg to10 mg⁄kg)⁄metformin (10 mg⁄kg to 180 mg⁄kg) blocked DIA. The derived theoretical effective doses for 50% of subjects (ED50) for the glibenclamide⁄metformin and glipizide⁄metformin combinations were 32.52 mg⁄kg and 32.42 mg⁄kg, respectively, and were significantly higher than the actual observed experimental ED50 values (7.57 mg⁄kg and 8.43 mg⁄kg, respectively).

CONCLUSION

Pretreatment with glibenclamide, glipizide or metformin blocked DIA in a dose-dependent manner, and combining either sulfonylurea with metformin produced even greater effects. The observed ED50s for the combinations were approximately fourfold lower than the calculated additive effects. These data indicate that sulfonylureas interact to produce antagonism of DIA. Combination therapy is a common second-line treatment for patients with diabetes and metabolic syndrome, a group that experiences pain from multiple sources. The results suggest that at least some anti-inflammatory agents may not be effective in this group.

Rhinacanthus nasutus Ameliorates Cytosolic and Mitochondrial Enzyme Levels in Streptozotocin-Induced Diabetic Rats

The present study was conducted to evaluate the therapeutic efficacy of Rhinacanthus nasutus (R. nasutus) on mitochondrial and cytosolic enzymes in streptozotocin-induced diabetic rats. The rats were divided into five groups with 6 rats in each group. The methanolic extract of R. nasutus was orally administered at a dose of 200 mg/kg/day, and glibenclamide was administered at a dose of 50 mg/kg/day. All animals were treated for 30 days and were sacrificed. The activities of both intra- and extramitochondrial enzymes including glucose-6-phosphate dehydrogenase (G6PDH), succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), and lactate dehydrogenase (LDH) were measured in the livers of the animals. The levels of G6PDH, SDH, and GDH were significantly reduced in the diabetic rats but were significantly increased after 30 days of R. nasutus treatment. The increased LDH level in diabetic rats exhibited a significant reduction after treatment with R. nasutus. These results indicate that the administration of R. nasutus altered the activities of oxidative enzymes in a positive manner, indicating that R. nasutus improves mitochondrial energy production. Our data suggest that R. nasutus should be further explored for its role in the treatment of diabetes mellitus.

Combination of glibenclamide-metformin HCl for the treatment of type 2 diabetes mellitus

INTRODUCTION

Combination of glibenclamide (glyburide in the U.S.) and metformin hydrochloride simultaneously addresses two different but complimentary mechanisms to improve glycemic control in type 2 diabetes.

AREAS COVERED

The pharmacokinetics, efficacy, and side effect profile of the oral combination of glibenclamide-metformin are reviewed.

EXPERT OPINION

Those patients, uncontrolled with single oral agent sulfonylurea or metformin alone, benefit from combination glibenclamide-metformin. There is improvement in fasting plasma glucose, HbA(1C), and post-prandial glucose control, and patients are more likely to achieve a HbA(1C) < 7%. Initiation should be started at the lowest doses and titrated to get the desired effect. Combination therapy allows for reduced pill burden while treating a multifactorial disease by two different mechanisms. Practitioners should be cognizant of risks of hypoglycemia and the theoretical potential for lactic acidosis in the elderly and those with renal impairment. We caution the use of glibenclamide-metformin in patients at risk for cardiovascular disease. Therapy should be individualized, but overall, combination of glibenclamide-metformin should be considered in patients, without renal or cardiovascular impairment, who are not controlled on monotherapy alone. Alternatively, practitioners may want to weigh the efficacy and safety of available dipeptidyl-peptidase-4 inhibitor-metformin combinations to those of glibenclamide-metformin when considering combination therapy.

Inhibitors of fatty acid synthesis in prokaryotes and eukaryotes as anti-infective, anticancer and anti-obesity drugs

There is a large range of diseases, such diabetes and cancer, which are connected to abnormal fatty acid metabolism in human cells. Therefore, inhibitors of human fatty acid synthase have great potential to manage or treat these diseases. In prokaryotes, fatty acid synthesis is important for signaling, as well as providing starting materials for the synthesis of phospholipids, which are required for the formation of the cell membrane. Recently, there has been renewed interest in the development of new molecules that target bacterial fatty acid synthases for the treatment of bacterial diseases. In this review, we look at the differences and similarities between fatty acid synthesis in humans and bacteria and highlight various small molecules that have been shown to inhibit either the mammalian or bacterial fatty acid synthase or both.