Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts

The Cardiometabolic Impact of Rebaudioside A Exposure during the Reproductive Stage

The consumption of non-sugar sweeteners (NSS) has increased during pregnancy. The European Food Safety Agency suggested that steviol glycosides, such as Rebaudioside A (RebA), the major sweetener component of stevia, are safe for humans up to a dose of 4 mg/kg body weight/day. However, the World Health Organization recommended in 2023 the restraint of using NSS, including stevia, at any life stage, highlighting the need to study NSS safety in early periods of development. We aimed to study the mitochondrial and cardiometabolic effects of long-term RebA consumption during the reproductive stage of the life cycle. Female rats were exposed to RebA (4 mg steviol equivalents/kg body weight/day) in the drinking water from 4 weeks before mating until weaning. Morphometry, food and water consumption, glucose and lipid homeostasis, heart structure, function, and mitochondrial function were assessed. RebA showed an atrophic effect in the heart, decreasing cardiomyocyte cross-sectional area and myocardial fibrosis without repercussions on cardiac function. Mitochondrial and myofilamentary functions were not altered. Glucose tolerance and insulin sensitivity were not affected, but fasting glycemia and total plasma cholesterol decreased. This work suggests that this RebA dose is safe for female consumption during the reproductive stage, from a cardiometabolic perspective. However, studies on the effects of RebA exposure on the offspring are mandatory.

Biological activity and structural modification of isosteviol over the past 15 years

Isosteviol is a tetracyclic diterpenoid obtained by hydrolysis of stevioside. Due to its unique molecular skeleton and extensive pharmacological activities, isosteviol has attracted more and more attention from researchers. This review summarized the structural modification, pharmacological activity and microbial transformation of isosteviol from 04/2008 to 10/2023. In addition, the research history, structural characterization, and pharmacokinetics of isosteviol were also briefly reviewed. This review aims to provide useful literature resources and inspirations for the exploration of diterpenoid drugs.

The Natural Sweetener Stevia: An Updated Review on its Phytochemistry, Health Benefits, and Anti-diabetic Study

Stevia rebaudiana Bertoni is one of the significant high qualities of non-caloric sugar substitute sweetener plants against diabetes disease. Diabetes mellitus is one of the most common metabolic diseases caused by insulin secretion defects, insulin resistance in peripheral tissues, or both. Stevia rebaudiana is a perennial shrub of the Compositae family that is grown in several places around the world. It contains a plethora of different bioactive constituents which are responsible for several activities and sweetness. This sweetness is due to the presence of steviol glycosides which is 100-300 times sweeter than sucrose. Furthermore, stevia reduces oxidative stress, lowering the risk of diabetes. Its leaves have been used to control and treat diabetes and a variety of other metabolic diseases. This review summarizes the history, bioactive constituents of S. rebaudiana extract, pharmacology, anti-diabetic activity, and its application, especially in food supplements.

Steviol glycosides from Stevia rebaudiana Bertoni mitigate lipid metabolism abnormalities in diabetes by modulating selected gene expression - An in vivo study

In diabetes, in parallel to hyperglycaemia, elevated serum lipids are also diagnosed, representing a high-risk factor for coronary heart disease and cardiovascular complications. The objective of this study was to unravel the mechanisms that underlie the potential of steviol glycosides (stevioside or rebaudioside A) administered at two doses (500 or 2500 mg/kg body weight for 5 weeks) to regulate lipid metabolism. In this paper, the expression of selected genes responsible for glucose and lipid metabolism (Glut4, Pparγ, Cebpa, Fasn, Lpl and Egr1) in the peripheral tissues (adipose, liver and muscle tissue) was determined using quantitative real-time PCR method. It was found that the supplementation of steviol glycosides affected the expression of Glut4, Cebpa and Fasn genes, depending on the type of the glycoside and its dose, as well as the type of tissue, whish in part may explain the lipid-regulatory potential of steviol glycosides in hyperglycaemic conditions. Nevertheless, more in-depth studies, including human trials, are needed to confirm these effects, before steviol glycosides can be used in the therapy of type 2 diabetes.

Antioxidant Activity of Leaf Extracts from Stevia rebaudiana Bertoni Exerts Attenuating Effect on Diseased Experimental Rats: A Systematic Review and Meta-Analysis

Stevia (Stevia rebaudiana Bertoni) is an aromatic plant known for its high sweetening power ascribed to its glycosides. Stevia also contains several bioactive compounds showing antioxidant, antiproliferative, antimicrobial, and anti-inflammatory activities. Since inflammation and oxidative stress play critical roles in the pathogenesis of many diseases, stevia emerges as a promising natural product that could support human health. In this study we set out to investigate the way stevia affects oxidative stress markers (e.g., SOD, CAT, GPx, GSH, MDA) in diseased rats administered stevia leaf extracts or glycosides. To this end, we performed an inclusive literature search, following PRISMA guidelines, and recruited multivariate meta-analysis and meta-regression to synthesize all available data on experimental animal models encountering (a) healthy, (b) diseased, and (c) stevia-treated diseased rats. From the 184 articles initially retrieved, 24 satisfied the eligibility criteria, containing 104 studies. Our results demonstrate that regardless of the assay employed, stevia leaf extracts restored all oxidative stress markers to a higher extent compared to pure glycosides. Meta-regression analysis revealed that results from SOD, CAT, GSH, and TAC assays are not statistically significantly different (p = 0.184) and can be combined in meta-analysis. Organic extracts from stevia leaves showed more robust antioxidant properties compared to aqueous or hydroalcoholic ones. The restoration of oxidative markers ranged from 65% to 85% and was exhibited in all tested tissues. Rats with diabetes mellitus were found to have the highest restorative response to stevia leaf extract administration. Our results suggest that stevia leaf extract can act protectively against various diseases through its antioxidant properties. However, which of each of the multitude of stevia compounds contribute to this effect, and to what extent, awaits further investigation.

Effects of Stevioside on the Expressions of GLUT 1, GLUT 3, and GLUT 4 Proteins in Diabetic Rat Placenta

The placenta provides maternal-fetal nutrient transport. The primary source of energy for fetus development is glucose and maternal-fetal glucose transport occurs through glucose transporters (GLUTs). Stevioside, a component of Stevia rebaudiana Bertoni, is used for medicinal and commercial purposes. We aim to determine the effects of stevioside on GLUT 1, GLUT 3, and GLUT 4 proteins expressions in diabetic rat placentas. The rats are divided into four groups. A single dose of streptozotocin (STZ) is administered to form the diabetic groups. Pregnant rats receive stevioside to form the stevioside and diabetic + stevioside groups. According to immunohistochemistry results, GLUT 1 protein is found in both the labyrinth and junctional zones. GLUT 3 protein is limited in the labyrinth zone. GLUT 4 protein is detected in trophoblast cells. According to Western blotting results, on the 15th and 20th days of pregnancy, there is no difference in the expression of GLUT 1 protein between groups. On the 20th day of pregnancy, the expression of GLUT 3 protein in the diabetic group is statistically higher compared to the control group. On the 15th day and 20th day of pregnancy, the expression of GLUT 4 protein in the diabetic group is statistically lower compared to the control group. Insulin levels in blood samples derived from rat abdominal aorta are determined by the ELISA method. According to the ELISA results, there is no difference in insulin protein concentration between groups. Stevioside treatment reduces GLUT 1 protein expression under diabetic conditions.

Steviol Glycosides from Stevia rebaudiana: An Updated Overview of Their Sweetening Activity, Pharmacological Properties, and Safety Aspects

This literature-based review synthesizes the available scientific information about steviol glycosides as natural sweeteners and molecules with therapeutic potential. In addition, it discusses the safety concerns regarding human consumption. Steviol glycosides exhibit a superior sweetener proficiency to that of sucrose and are noncaloric, noncariogenic, and nonfermentative. Scientific evidence encourages stevioside and rebaudioside A as sweetener alternatives to sucrose and supports their use based on their absences of harmful effects on human health. Moreover, these active compounds isolated from Stevia rebaudiana possess interesting medicinal activities, including antidiabetic, antihypertensive, anti-inflammatory, antioxidant, anticancer, and antidiarrheal activity. The described bioactivities of steviol glycosides deserve special attention based on their dose dependence and specific pathological situations. Further clinical research is needed to understand underlying mechanisms of action, therapeutic indexes, and pharmacological applications.

Caffeine and Its Antioxidant Properties-It Is All about Dose and Source

Caffeine is the most frequently used substance with a central nervous system stimulant effect, but its consumption is most often due to the intake of foods and drinks that contain it (coffee, tea, chocolate, food supplements with plant extracts of Guarana, Mate herba, Cola nuts). Due to its innocuity, caffeine is a safe xanthine alkaloid for human consumption in a wide range of doses, being used for its central nervous stimulating effect, lipolytic and diuresis-enhancing properties, but also as a permitted ergogenic compound in athletes. In addition to the mechanisms that explain the effects of caffeine on the targeted organ, there are many proposed mechanisms by which this substance would have antioxidant effects. As such, its consumption prevents the occurrence/progression of certain neurodegenerative diseases as well as other medical conditions associated with increased levels of reactive oxygen or nitrogen species. However, most studies that have assessed the beneficial effects of caffeine have used pure caffeine. The question, therefore, arises whether the daily intake of caffeine from food or drink has similar benefits, considering that in foods or drinks with a high caffeine content, there are other substances that could interfere with this action, either by potentiating or decreasing its antioxidant capacity. Natural sources of caffeine often combine plant polyphenols (phenol-carboxylic acids, catechins) with known antioxidant effects; however, stimulant drinks and dietary supplements often contain sugars or artificial sweeteners that can significantly reduce the effects of caffeine on oxidative stress. The objective of this review is to clarify the effects of caffeine in modulating oxidative stress and assess these benefits, considering the source and the dose administered.

Biosynthesis of silver nanoparticles using extracts of Stevia rebaudiana and evaluation of antibacterial activity

The present study reveals a simple, non-toxic and eco-friendly method for the "green" synthesis of Ag-NPs using hydroponic and soil medicinal plant Stevia rebaudiana extracts, the characterization of biosynthesized nanoparticles, as well as the evaluation of their antibacterial activity. Transmission electronic microscopy (TEM) and Dynamic Light Scattering (DLS) analysis confirmed that biosynthesized Ag-NPs are in the nano-size range (50-100 nm) and have irregular morphology. Biogenic NPs demonstrate antibacterial activity against Escherichia coli BW 25,113, Enterococcus hirae ATCC 9790, and Staphylococcus aureus MDC 5233. The results showed a more pronounced antibacterial effect on E. coli growth rate, in comparison with Gram-positive bacteria, which is linked to the differences in the structure of bacterial cell wall. Moreover, the Ag-NPs not only suppressed the growth of bacteria but also changed the energy-dependent H⁺-fluxes across the bacterial membrane. The change of H⁺-fluxes in presence of H⁺-translocating systems inhibitor, N,N'-dicyclohexylcarbodiimide (DCCD), proves the effect of Ag-NPs on the structure and permeability of the bacterial membrane. Overall, our findings indicate that the Ag-NPs synthesized by medicinal plant Stevia extracts may be an excellent candidate as an alternative to antibiotics against the tested bacteria.

Role of Oxidative Stress in the Pathogenesis of Atherothrombotic Diseases

Oxidative stress is generated by the imbalance between reactive oxygen species (ROS) formation and antioxidant scavenger system’s activity. Increased ROS, such as superoxide anion, hydrogen peroxide, hydroxyl radical and peroxynitrite, likely contribute to the development and complications of atherosclerotic cardiovascular diseases (ASCVD). In genetically modified mouse models of atherosclerosis, the overexpression of ROS-generating enzymes and uncontrolled ROS formation appear to be associated with accelerated atherosclerosis. Conversely, the overexpression of ROS scavenger systems reduces or stabilizes atherosclerotic lesions, depending on the genetic background of the mouse model. In humans, higher levels of circulating biomarkers derived from the oxidation of lipids (8-epi-prostaglandin F_2α, and malondialdehyde), as well as proteins (oxidized low-density lipoprotein, nitrotyrosine, protein carbonyls, advanced glycation end-products), are increased in conditions of high cardiovascular risk or overt ASCVD, and some oxidation biomarkers have been reported as independent predictors of ASCVD in large observational cohorts. In animal models, antioxidant supplementation with melatonin, resveratrol, Vitamin E, stevioside, acacetin and n-polyunsaturated fatty acids reduced ROS and attenuated atherosclerotic lesions. However, in humans, evidence from large, placebo-controlled, randomized trials or prospective studies failed to show any athero-protective effect of antioxidant supplementation with different compounds in different CV settings. However, the chronic consumption of diets known to be rich in antioxidant compounds (e.g., Mediterranean and high-fish diet), has shown to reduce ASCVD over decades. Future studies are needed to fill the gap between the data and targets derived from studies in animals and their pathogenetic and therapeutic significance in human ASCVD.

Exosomes Derived from Human Amniotic Fluid Mesenchymal Stem Cells Preserve Microglia and Neuron Cells from Aβ

BACKGROUND

Neuroinflammation is involved in neuronal cell death that occurs in neurodegenerative diseases such as Alzheimer's disease (AD). Microglia play important roles in regulating the brain amyloid beta (Aβ) levels, so immunomodulatory properties exerted by mesenchymal stem cells may be exploited to treat this pathology. The evidence suggests that the mechanism of action of human amniotic fluid stem cells (hAFSCs) is through their secretome, which includes exosomes (exo).

METHODS

We examined the effect of exosomes derived from human amniotic fluid stem cells (hAFSCs-exo) on activated BV-2 microglia cells by lipopolysaccharide (LPS) as a neuroinflammation model. To investigate the exo effect on the interplay between AD neurons and microglia, SH-SY5Y neuroblastoma cells treated with Aβ were exposed to a conditioned medium (CM) obtained from activated BV-2 or co-culture systems.

RESULTS

We found that the upregulation of the markers of pro-inflammatory microglia was prevented when exposed to hAFSC-exo whereas the markers of the anti-inflammatory macrophage phenotype were not affected. Interestingly, the hAFSC-exo pretreatment significantly inhibited the oxidative stress rise and apoptosis occurring in the neurons in presence of both microglia and Aβ.

CONCLUSION

We demonstrated that hAFSC-exo mitigated an inflammatory injury caused by microglia and significantly recovered the neurotoxicity, suggesting that hAFSC-exo may be a potential therapeutic agent for inflammation-related neurological conditions, including AD.

Natural sweetener Stevia rebaudiana: Functionalities, health benefits and potential risks

Stevia rebaudiana is a South American plant, the cultivation of which is increasing worldwide due to its high content of sweet compounds. Stevia sweetness is mainly due to steviol glycosides, that are ~250-300 times sweeter than sucrose. Many studies have suggested the benefits of Stevia extract over sugar and artificial sweeteners, but it is still not a very popular sugar substitute. This review summarizes current data on the biological activities of S. rebaudiana extract and its individual glycosides, including anti-hypertensive, anti-obesity, anti-diabetic, antioxidant, anti-cancer, anti-inflammatory, and antimicrobial effects and improvement of kidney function. Possible side effects and toxicity of Stevia extract are also discussed.

The role of metabolites of steviol glycosides and their glucosylated derivatives against diabetes-related metabolic disorders

Diabetes mellitus (DM), characterized by abnormal carbohydrate, lipid, and protein metabolism, is a metabolic disorder caused by a shortage of insulin secretion or decreased sensitivity of target cells to insulin. In addition to changes in lifestyle, a low-calorie diet is recommended to reduce the development of DM. Steviol glycosides (SGs), as natural sweeteners, have gained attention as sucrose alternatives because of their advantages of high sweetness and being low calorie. Most SGs with multiple bioactivities are beneficial to regulate physiological functions. Though SGs have been widely applied in food industry, there is little data on their glucosylated derivatives that are glucosylated steviol glycosides (GSGs). In this review, we have discussed the metabolic fate of GSGs in contrast to SGs, and the molecular mechanisms of glycoside metabolites against diabetes-related metabolic disorders are also summarized. SGs are generally extracted from the Stevia leaf, while GSGs are mainly manufactured using enzymes that transfer glucose units from a starch source to SGs. Results from this study suggest that SGs and GSGs share same bioactive metabolites, steviol and steviol glucuronide (SVG), which exhibit anti-hyperglycemic effects by activating glucose-induced insulin secretion to enhance pancreatic β-cell function. In addition, steviol and SVG have been found to ameliorate the inflammatory response, lipid imbalance, myocardial fibrosis and renal functions to modulate diabetes-related metabolic disorders. Therefore, both SGs and GSGs may be used as potential sucrose alternatives and/or pharmacological alternatives for preventing and treating metabolic disorders.

The anti-diabetic activities of natural sweetener plant Stevia: an updated review

Diabetes mellitus is one of the key metabolic diseases cause due to defects in the secretion of insulin, insulin resistance in peripheral tissues, or both. Plants remained an important source of nutrition as well as medicine. Stevia rebaudiana Bertoni is one of the important high qualities non-caloric sugar substitute sweetener plants against diabetes disease. The compounds like steviol, rebaudioside A, stevioside, etc. can lower the sugar level many fold. In addition, it decreases oxidative stress, hence reduces the risk of diabetes. Its leaves have been used for the control and treatment of diabetes and many other metabolic diseases. In animal model experiments it reduces blood sugar level and promotes liver and kidney functions. In this review, we highlighted the most recent literature on the safe use of Stevia for the treatment of diabetes, its use as a functional food, and its mode of therapeutic action in different animal model experiments. However, keeping Stevia as a model plant; detailed investigations are needed for the identification of new metabolites and its use against diabetes and related diseases.

Steviol Glycosides Supplementation Affects Lipid Metabolism in High-Fat Fed STZ-Induced Diabetic Rats

A number of health-promoting properties of Stevia rebaudiana Bertoni and its glycosides, including the antihyperglycemic activity, have been found. The mechanisms of the antidiabetic action of stevia have not been fully understood. The aim of this study was to evaluate the effects of supplementary steviol glycosides on high-fat fed streptozotocin-induced diabetic rats with particular attention to lipid metabolism. The experiment was conducted on 70 male Wistar rats, of which 60 were fed a high-fat diet for 8 weeks followed by intraperitoneal injection of streptozotocin, to induce type 2 diabetes. Afterwards, rats were divided into six groups and fed a high-fat diet supplemented with pure stevioside or rebaudioside A, at two levels (500 or 2500 mg/kg body weight (b.w.)) for 5 weeks. Three additional groups: diabetic untreated, diabetic treated with metformin, and healthy, served as respective controls. Blood and dissected internal organs were collected for hematological, biochemical, and histopathological tests. It was found that dietary supplementation with steviol glycosides did not affect blood glucose, insulin, and insulin resistance indices, antioxidant biomarkers, but normalized hyperlipidemia and affected the appetite, as well as attenuated blood liver and kidney function indices, and reduced tissular damage in diabetic rats. Steviol glycosides normalize lipid metabolism and attenuate internal organs damage in diabetes.

Effect of stevia on the gut microbiota and glucose tolerance in a murine model of diet-induced obesity

Artificial sweeteners have been shown to induce glucose intolerance by altering the gut microbiota; however, little is known about the effect of stevia. Here, we investigate whether stevia supplementation induces glucose intolerance by altering the gut microbiota in mice, hypothesizing that stevia would correct high fat diet-induced glucose intolerance and alter the gut microbiota. Mice were split into four treatment groups: low fat, high fat, high fat + saccharin and high fat + stevia. After 10 weeks of treatment, mice consuming a high fat diet (60% kcal from fat) developed glucose intolerance and gained more weight than mice consuming a low fat diet. Stevia supplementation did not impact body weight or glucose intolerance. Differences in species richness and relative abundances of several phyla were observed in low fat groups compared to high fat, stevia and saccharin. We identified two operational taxonomic groups that contributed to differences in beta-diversity between the stevia and saccharin groups: Lactococcus and Akkermansia in females and Lactococcus in males. Our results demonstrate that stevia does not rescue high fat diet-induced changes in glucose tolerance or the microbiota, and that stevia results in similar alterations to the gut microbiota as saccharin when administered in concordance with a high fat diet.

Steviol, the active principle of the stevia sweetener, causes a reduction of the cells of the immunological system even consumed in low concentrations

AIM

Steviol is a natural diterpenoid glycoside isolated from Stevia rebaudiana Bertoni leaves and widely used as a non-caloric sweetener. In addition to their sweet taste, Steviol glycosides may also have some therapeutic benefits. There are few reports on the cytotoxicity of Steviol in human cells. Our objective was to test this sweetener under and at average concentrations of consumption, evaluating parameters of cytotoxicity, genotoxicity, and immunotoxicity.

METHODS

For this purpose, we made use of lymphocyte cultures and the analysis of their CD3⁺, CD4⁺, and CD8⁺ subpopulations. In a complementary way, the mechanism of action is proposed here by computational methods.

RESULTS AND CONCLUSION

Our results showed that Steviol reduces the number of lymphocytes due to falls of CD4⁺, CD8⁺, and CD4⁺CD8⁺ subpopulations. Besides, we observed an increase in the level of DNA damage and a gradual incidence of structural changes in the lymphocyte chromosomal sets. It was possible to propose that Steviol modulates gene expression, mainly interfering with the SESN1, NAP1L1, SOX4, and TREX1 genes. Although Steviol is used globally as a sweetener, its use should be cautious, as our study points out that Steviol has cytotoxic, genotoxic and mutagenic effects in the concentrations and conditions tested in the culture of human lymphocyte cells.

Glucose transporters in cardiovascular system in health and disease

Glucose transporters are essential for the heart to sustain its function. Due to its nature as a high energy-consuming organ, the heart needs to catabolize a huge quantity of metabolic substrates. For optimized energy production, the healthy heart constantly switches between various metabolites in accordance with substrate availability and hormonal status. This metabolic flexibility is essential for the maintenance of cardiac function. Glucose is part of the main substrates catabolized by the heart and its use is fine-tuned via complex molecular mechanisms that include the regulation of the glucose transporters GLUTs, mainly GLUT4 and GLUT1. Besides GLUTs, glucose can also be transported by cotransporters of the sodium-glucose cotransporter (SGLT) (SLC5 gene) family, in which SGLT1 and SMIT1 were shown to be expressed in the heart. This SGLT-mediated uptake does not seem to be directly linked to energy production but is rather associated with intracellular signalling triggering important processes such as the production of reactive oxygen species. Glucose transport is markedly affected in cardiac diseases such as cardiac hypertrophy, diabetic cardiomyopathy and heart failure. These alterations are not only fingerprints of these diseases but are involved in their onset and progression. The present review will depict the importance of glucose transport in healthy and diseased heart, as well as proposed therapies targeting glucose transporters.

Stevia rebaudiana extract attenuate metabolic disorders in diabetic rats via modulation of glucose transport and antioxidant signaling pathways and aquaporin-2 expression in two extrahepatic tissues

Today, plant-based therapies have been attracted attention to overcome diabetes complications. This study was an attempt to evaluate whether antidiabetic and nephroprotective effects of Stevia Rebaudiana Bertoni (SRB) can be exerted via upregulation of GLUT-4, SNAP23, and Stx4 in skeletal muscles or modulation of AQP2 mRNA expression and antioxidant signaling pathway activity (Nrf2/Keap1) in kidneys. To achieve this aim, diabetes was induced via STZ-nicotinamide (STZ-NA). Diabetes increased the level of Blood Urea Nitrogen (BUN), serum creatinine, Fasting Blood Sugar (FBS), and Keap1 mRNA expression, which was coincide with reduction in mRNA levels of Nrf2, GLUT4, SNAP23, and Stx4. SRB and metformin compensate mentioned variables. However, SRB extract was more effective than metformin to increase the levels of GLUT4 and Nrf2 mRNA. It seems that SRB might attenuate the diabetic complications via manipulating the glucose uptake components in peripheral tissues and might exert the nephroprotective effects by modulation of AQP2, and Nrf2/Keap1 mRNA expression. PRACTICAL APPLICATIONS: Synthetic antidiabetic drugs have been only partially successful in controlling the diabetic complications. Moreover, use of these drugs is associated with a number of adverse effects. Over the past few years, a renewed attention has been paid to the prevention and treatment of diabetes using medicinal plants and functional foods. SRB that have been known as natural sweetener for centuries, is a such natural agent that has high source of various phytochemicals with antidiabetic, renal protective, antitumor, and antioxidant properties. In the current study, possible molecular mechanisms of insulin-mimetic and nephroprotective effects of SRB extract was evaluated in diabetic rats. Due to powerful antihyperglycemic and nephroprotective effects of SRB extract that were showed in this study and previous studies, hence the fact that SRB is to be highlighted for future research as a new therapeutic agent for diabetes.

Plant-Based Antidiabetic Nanoformulations: The Emerging Paradigm for Effective Therapy

Diabetes mellitus is a life-threatening metabolic syndrome. Over the past few decades, the incidence of diabetes has climbed exponentially. Several therapeutic approaches have been undertaken, but the occurrence and risk still remain unabated. Several plant-derived small molecules have been proposed to be effective against diabetes and associated vascular complications via acting on several therapeutic targets. In addition, the biocompatibility of these phytochemicals increasingly enhances the interest of exploiting them as therapeutic negotiators. However, poor pharmacokinetic and biopharmaceutical attributes of these phytochemicals largely restrict their clinical usefulness as therapeutic agents. Several pharmaceutical attempts have been undertaken to enhance their compliance and therapeutic efficacy. In this regard, the application of nanotechnology has been proven to be the best approach to improve the compliance and clinical efficacy by overturning the pharmacokinetic and biopharmaceutical obstacles associated with the plant-derived antidiabetic agents. This review gives a comprehensive and up-to-date overview of the nanoformulations of phytochemicals in the management of diabetes and associated complications. The effects of nanosizing on pharmacokinetic, biopharmaceutical and therapeutic profiles of plant-derived small molecules, such as curcumin, resveratrol, naringenin, quercetin, apigenin, baicalin, luteolin, rosmarinic acid, berberine, gymnemic acid, emodin, scutellarin, catechins, thymoquinone, ferulic acid, stevioside, and others have been discussed comprehensively in this review.

Effects of Stevia Rebaudiana on Glucose Homeostasis, Blood Pressure and Inflammation: A Critical Review of Past and Current Research Evidence

The prevalence of obesity and its related comorbidities continues to rise in the United States and worldwide. Insulin resistance, increased inflammation and oxidative stress are the major pathogenic mechanisms involved in obesity-associated co-morbid conditions. Major efforts to curb the rising tide of obesity, including lifestyle modifications, anti-obesity medications and surgical interventions have shown minimal success. Therefore, introducing new methods to combat obesity, diabetes and associated disorders are desperately needed. Stevia rebaudiana, a natural, non-caloric sweetener has generated significant interest in the scientific community due to its effects on glucose homeostasis, blood pressure and inflammation, all known consequences of obesity. In this review, we assess the effects of Stevia on these parameters in humans as well as in animal models, highlighting its potential role as an effective intervention for the major cardiovascular risk factors associated with obesity.

Natural Alternative Sweeteners and Diabetes Management

PURPOSE OF REVIEW

The goal of this review is to discuss the data on natural alternative sweeteners and their effects on glucose homeostasis and other metabolic parameters within the past five years. We sought to answer whether common natural alternative sweeteners have a positive or negative effect on glucose control in both human and animal models, and whether the data supports their widespread use as a tool to help reduce the prevalence of diabetes and associated comorbid conditions.

RECENT FINDINGS

Recent studies suggest that natural alternative sweeteners may reduce hyperglycemia, improve lipid metabolism, and have antioxidant effects particularly in those that have baseline diabetes. Diabetes and metabolic syndrome have become a global healthcare crisis and the sugar overconsumption plays a major role. The use of artificial sweeteners has become more prevalent to improve insulin resistance in those with diabetes, obesity, and metabolic syndrome, although the evidence does not support this result. There are however some promising data to suggest that natural alternative sweeteners may be a better alternative to sugar and artificial sweeteners.

Impact of hyperinsulinemia and hyperglycemia on valvular interstitial cells - A link between aortic heart valve degeneration and type 2 diabetes

Type 2 diabetes is a known risk factor for cardiovascular diseases and is associated with an increased risk to develop aortic heart valve degeneration. Nevertheless, molecular mechanisms leading to the pathogenesis of valve degeneration in the context of diabetes are still not clear. Hence, we hypothesized that classical key factors of type 2 diabetes, hyperinsulinemia and hyperglycemia, may affect signaling, metabolism and degenerative processes of valvular interstitial cells (VIC), the main cell type of heart valves. Therefore, VIC were derived from sheep and were treated with hyperinsulinemia, hyperglycemia and the combination of both. The presence of insulin receptors was shown and insulin led to increased proliferation of the cells, whereas hyperglycemia alone showed no effect. Disturbed insulin response was shown by impaired insulin signaling, i.e. by decreased phosphorylation of Akt/GSK-3α/β pathway. Analysis of glucose transporter expression revealed absence of glucose transporter 4 with glucose transporter 1 being the predominantly expressed transporter. Glucose uptake was not impaired by disturbed insulin response, but was increased by hyperinsulinemia and was decreased by hyperglycemia. Analyses of glycolysis and mitochondrial respiration revealed that VIC react with increased activity to hyperinsulinemia or hyperglycemia, but not to the combination of both. VIC do not show morphological changes and do not acquire an osteogenic phenotype by hyperinsulinemia or hyperglycemia. However, the treatment leads to increased collagen type 1 and decreased α-smooth muscle actin expression. This work implicates a possible role of diabetes in early phases of the degeneration of aortic heart valves.

Cardiac fibroblast activation and hyaluronan synthesis in response to hyperglycemia and diet-induced insulin resistance

Diabetic patients are at a greater risk of heart failure due to diabetic cardiomyopathy and worsened outcome post-myocardial infarction. While the molecular mechanisms remain unclear, fibrosis and chronic inflammation are common characteristics of both conditions. Diabetes mellitus (types I and II) results in excessive hyaluronan (HA) deposition in vivo, and hyperglycemia stimulates HA synthesis for several cell types in vitro. HA-rich extracellular matrix contributes to fibrotic, hyperplastic and inflammatory disease progression. We hypothesized that excessive hyperglycemia-driven HA accumulation may contribute to pathological fibroblast activation and fibrotic remodelling in diabetic patients. Therefore, we analysed the impact of both hyperglycemia and diet-induced obesity and insulin resistance on HA matrix formation and cardiac fibroblast activation. Here we report that cardiac fibroblasts isolated from mice on a diabetogenic diet acquire pro-fibrotic gene expression without a concomitant increase in HA matrix deposition. Additionally, hyperglycemia alone does not stimulate HA synthesis or cardiac fibroblast activation in vitro, suggesting that the direct effect of hyperglycemia on fibroblasts is not the primary driver of fibrotic remodelling in cardiac diabetic maladaptation.

Stevioside modulates oxidative damage in the liver and kidney of high fat/low streptozocin diabetic rats

This study investigated the potential of stevioside to prevent oxidative DNA damage in the liver and kidney of type 2 diabetes mellitus (T2DM) using high fat-low streptozocin rat model. Rats were treated daily with 12.5, 25 and 50 mg/kg stevioside orally for 21 days. Levels of biomarkers of T2DM, lipid profile and oxidative stress were assayed spectrophotometrically. The DNA ladder assay method was used to assess DNA fragmentation in the liver and kidney while computational analysis was used to predict the mechanisms of antidiabetic properties of stevioside. Stevioside significantly (p < 0.05) decreased the levels of plasma glucose, insulin, dipeptidyl peptidase IV and activities of kidney angiotensin converting enzyme. Stevioside significantly reduced oxidative stress by decreasing the levels of lipid peroxidation and nitric oxide in the liver and kidney; thereby, reducing the extent of DNA fragmentation in the liver and kidney of the diabetic rats. The in silico analysis showed that the ability of stevioside to exert these effects is linked to its inhibition of beta-adrenergic receptor kinase and G-protein-coupled receptor kinase. The results of this study suggest that the prevention of DNA fragmentation may be an additional benefit of the use of stevioside in the management of T2DM.