Fucosylated Chondroitin Sulfate from Sea Cucumber in Combination with Rosiglitazone Improved Glucose Metabolism in the Liver of the Insulin-Resistant Mice

Sulfated polysaccharides in sea cucumbers and their biological properties: A review

Sea cucumbers contain a wide range of biomolecules, including sulfated polysaccharides (SPs), with immense therapeutic and nutraceutical potential. SPs in sea cucumbers are mainly fucosylated chondroitin sulfate (FCS) and fucan sulfate (FS) which exhibit a series of pharmacological effects, including anticoagulant activity, in several biological systems. FCS is a structurally distinct glycosaminoglycan in the sea cucumber body wall, and its biological properties mainly depend on the degree of sulfation, position of sulfate group, molecular weight, and distribution of branches along the backbone. So far, FCS and FS have been recognized for their antithrombotic, anti-inflammatory, anticancer, antidiabetic, anti-hyperlipidemic, anti-obesity, and antioxidant potential. However, the functions of these SPs are mainly dependent on the species, origins, harvesting season, and extraction methods applied. This review focuses on the SPs of sea cucumbers and how their structural diversities affect various biological activities. In addition, the mechanism of actions of SPs, chemical structures, factors affecting their bioactivities, and their extraction methods are also discussed.

Berberine Ameliorates Insulin Resistance by Inhibiting IKK/NF-κB, JNK, and IRS-1/AKT Signaling Pathway in Liver of Gestational Diabetes Mellitus Rats

Introduction: Berberine is derived from rhizoma coptidis, a well-known Traditional Chinese herbal Medicine that has been found to be effective in the treatment of type 2 diabetes mellitus in recent years. The aim of the present study was to investigate the effects of berberine on a gestational diabetes mellitus (GDM) rat model and the related mechanisms. Methods: GDM was induced in Sprague-Dawley rats using a high-fat diet before and during pregnancy. Berberine (100 mg/kg/day) was administered from the 7th to 20th day of pregnancy. Insulin resistance (IR), glucose tolerance, and maternal, fetal, and placental weight were determined. Liver histopathological analysis, as well as analysis of C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), inhibitor kappa B kinaseβ (IKKβ), nuclear factor kappa-B (NF-κB), c-Jun N-terminal kinase (JNK), insulin receptor substrate-1 (IRS-1), and protein kinase B (AKT), was performed at the end of pregnancy. Results: Treatment of GDM rats with berberine markedly decreased IR, the number of dead and absorptive fetuses, maternal body weight gain, and fetal and placental weight compared with GDM without berberine. Furthermore, berberine decreased CRP and TNF-α levels, IKKβ expression, NF-κB P65 nuclear translocation, and changed the phosphorylation of JNK, IRS-1, and AKT in the liver of GDM rats. Conclusions: Berberine improved IR and maternal-fetal outcomes of GDM rats, possibly through modulation of IKK/NF-κB, JNK, and IRS-1/AKT signaling pathways in the liver. Therefore, berberine may be a potential GDM treatment.

Holothurian fucosylated chondroitin sulfates and their potential benefits for human health: Structures and biological activities

Fucosylated chondroitin sulfates (FCS) are a sulfated polysaccharide exclusively existing in the body wall of sea cucumber. FCS possesses a mammalian chondroitin sulfate like backbone, namely repeating disaccharides units composed of GlcA and GalNAc, with fucosyl branches linked to GlcA and/or GalNAc residues. It is found that FCS can prevent unhealthy dietary pattern-induced metabolic syndromes, including insulin resistance and β-cell function improvement, anti-inflammation, anti-hyperlipidemia, and anti-adipogenesis. Further studies show that those activities of FCS might be achieved through positively modulating gut microbiota composition. Besides, FCS also show therapeutic efficacy in cancer, HIV infection, and side effects of cyclophosphamide. Furthermore, bioactivities of FCS are closely affected by their molecular weights, sulfation pattern of the fucosyl branches, and chain conformations. This review summarizes the recent 20 years studies to provide references for the future studies and applications of FCS in functional foods or drugs.

Pharmacological Activities of Sulfated Fucose-Rich Polysaccharides after Oral Administration: Perspectives for the Development of New Carbohydrate-Based Drugs

Marine organisms are a source of active biomolecules with immense therapeutic and nutraceutical potential. Sulfated fucose-rich polysaccharides are present in large quantities in these organisms with important pharmacological effects in several biological systems. These polysaccharides include sulfated fucan (as fucoidan) and fucosylated chondroitin sulfate. The development of these polysaccharides as new drugs involves several important steps, among them, demonstration of the effectiveness of these compounds after oral administration. The oral route is the more practical, comfortable and preferred by patients for long-term treatments. In the past 20 years, reports of various pharmacological effects of these polysaccharides orally administered in several animal experimental models and some trials in humans have sparked the possibility for the development of drugs based on sulfated polysaccharides and/or the use of these marine organisms as functional food. This review focuses on the main pharmacological effects of sulfated fucose-rich polysaccharides, with an emphasis on the antidislipidemic, immunomodulatory, antitumor, hypoglycemic and hemostatic effects.

Structure-function relationship analysis of fucoidan from sea cucumber (Holothuria tubulosa) on ameliorating metabolic inflammation

The structure-function relationships of sea cucumber fucoidan has been seldom investigated. In this study, the effect of fucoidan which extracted from sea cucumber Holothuria tubulosa (Ht-FUC) with different molecular weight and chain conformation (Ht1/2/3/4) in metabolic inflammation was investigated. A co-cultured system comprising adipocytes and macrophages was used to explore the impact in vitro. The high-fat high-sucrose diet (HFD)-fed obese mice model was established to verified the effect of Ht-FUC in vivo. The results demonstrated that all examined Ht-FUC attenuated the productions of inflammatory cytokines, promoted the M2 phenotypic polarization of co-cultured macrophage by activating PPARγ. Furthermore Ht-FUC impressed lipolysis of the co-cultured adipocytes by inhibiting TLR4/NF-κB-dependent pathway. In vivo, Ht-FUC especially reduced serum inflammation level, attenuated M1/M2 polarization of liver Kupffer cells, and attenuated inflammatory infiltration of epididymal adipose tissue. Consistently, Ht3 played the best effect, and may be more beneficial for the intervention of metabolic disease. PRACTICAL APPLICATIONS: In this study, the structure-function relationships of fucoidan extracted from Holothuria tubulosa (Ht-FUC) on ameliorating metabolic inflammation was investigated for the first time. In this research, we reported that Ht-FUC ameliorating metabolic inflammation by improving FFA-induced macrophage polarization and lipolysis in both co-cultured system and obese mice. The study provides some theoretical basis for the high-value utilization of Ht-FUC with different molecular weight.

Northern Sea Cucumber (Cucumaria frondosa): A Potential Candidate for Functional Food, Nutraceutical, and Pharmaceutical Sector

Sea cucumber (Cucumaria frondosa) is the most abundant and widely distributed species in the cold waters of North Atlantic Ocean. C. frondosa contains a wide range of bioactive compounds, mainly collagen, cerebrosides, glycosaminoglycan, chondroitin sulfate, saponins, phenols, and mucopolysaccharides, which demonstrate unique biological and pharmacological properties. In particular, the body wall of this marine invertebrate is the major edible part and contains most of the active constituents, mainly polysaccharides and collagen, which exhibit numerous biological activities, including anticancer, anti-hypertensive, anti-angiogenic, anti-inflammatory, antidiabetic, anti-coagulation, antimicrobial, antioxidation, and anti- osteoclastogenic properties. In particular, triterpene glycosides (frondoside A and other) are the most researched group of compounds due to their potential anticancer activity. This review summarizes the latest information on C. frondosa, mainly geographical distribution, landings specific to Canadian coastlines, processing, commercial products, trade market, bioactive compounds, and potential health benefits in the context of functional foods and nutraceuticals.

Glycosaminoglycan from Apostichopus japonicus Improves Glucose Metabolism in the Liver of Insulin Resistant Mice

Holothurian glycosaminoglycan isolated from Apostichopus japonicus (named AHG) can suppress hepatic glucose production in insulin resistant hepatocytes, but its effects on glucose metabolism in vivo are unknown. The present study was conducted to investigate the effects of AHG on hyperglycemia in the liver of insulin resistant mice induced by a high-fat diet (HFD) for 12 weeks. The results demonstrated that AHG supplementation apparently reduced body weight, blood glucose level, and serum insulin content in a dose-dependent manner in HFD-fed mice. The protein levels and gene expression of gluconeogenesis rate-limiting enzymes G6Pase and PEPCK were remarkedly suppressed in the insulin resistant liver. In addition, although the total expression of IRS1, Akt, and AMPK in the insulin resistant liver was not affected by AHG supplementation, the phosphorylation of IRS1, Akt, and AMPK were clearly elevated by AHG treatment. These results suggest that AHG could be a promising natural marine product for the development of an antihyperglycemic agent.

Glycosaminoglycan from Apostichopus japonicus inhibits hepatic glucose production via activating Akt/FoxO1 and inhibiting PKA/CREB signaling pathways in insulin resistant hepatocytes

The aim of this study was to elucidate the effect and the underlying mechanism of glycosaminoglycan from Apostichopus japonicus (AHG) on hepatic glucose production (HGP) in insulin resistant hepatocytes. Insulin resistance was induced with high glucose (HG) for 24 h in primary hepatocytes. The results showed that AHG exhibited hypoglycemic activity at a relatively low concentration (1 μg mL^-1) and revealed non-toxic activity to insulin resistant hepatocytes even at 500 μg mL^-1 concentration. The HGP test showed that the treatment of AHG (10 μg mL^-1) for 3 h decreased HGP by 25% in insulin resistant hepatocytes. Quantitative PCR and western blot analysis revealed that AHG also ameliorated phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). The data revealed the mechanism of AHG in alleviating HGP via activating the Akt/FoxO1 signaling pathway and suppressing the PKA/CREB signaling pathway in insulin resistant hepatocytes. This finding suggests that AHG could be a potential marine natural product for the treatment of dysregulating glucose homeostasis.

Anti-Diabetic Effects and Mechanisms of Dietary Polysaccharides

Diabetes mellitus is a multifactorial, heterogeneous metabolic disorder, causing various health complications and economic issues, which apparently impacts the human's life. Currently, commercial diabetic drugs are clinically managed for diabetic treatment that has definite side effects. Dietary polysaccharides mainly derive from natural sources, including medicinal plants, grains, fruits, vegetables, edible mushroom, and medicinal foods, and possess anti-diabetic potential. Hence, this review summarizes the effects of dietary polysaccharides on diabetes and underlying molecular mechanisms related to inflammatory factors, oxidative stress, and diabetes in various animal models. The analysis of literature and appropriate data on anti-diabetic polysaccharide from electronic databases was conducted. In vivo and in vitro trials have revealed that treatment of these polysaccharides has hypoglycemic, hypolipidemic, antioxidant, and anti-inflammatory effects, which enhance pancreatic β-cell mass and alleviates β-cell dysfunction. It enhances insulin signaling pathways through insulin receptors and activates the PI3K/Akt pathway, and eventually modulates ERK/JNK/MAPK pathway. In conclusion, dietary polysaccharides can effectively ameliorate hyperglycemia, hyperlipidemia, low-grade inflammation, and oxidative stress in type 2 diabetes mellitus (T2DM), and, thus, consumption of polysaccharides can be a valuable choice for diabetic control.

Characterization and Hypoglycemic Activity of a Rhamnan-Type Sulfated Polysaccharide Derivative

Polysaccharide chromium (III) derivatives are gaining increasing attention in improving type 2 diabetes. In this study, the sulfated polysaccharide from Enteromorpha prolifera (SPE) with 4.8 kDa was prepared by specific enzymatic hydrolysis. The obtained SPE was used to prepare a rhamnan-type sulfated polysaccharide derivative (SPED). Results indicated that O-H, C=O, and S=O were effectively involved in the chelation of SPED (chromium content 20.26%). Acute (half lethal dose > 2.38 g/kg) and sub-acute toxicity showed that SPED had no damaging effects on mice. Anti-diabetic experiment demonstrated that SPED improved glucose metabolism. Moreover, SPED promoted the PI3K/PKB/GSK-3β signaling pathway by regulating mRNA expression of insulin receptors (IR), insulin receptor substrate 2 (IRS-2), phosphatidylinositol 3 kinase (PI3K), protein kinase B (PKB), and glycogen synthase kinase 3β (GSK-3β). In conclusion, the SPED might represent a novel marine-derived candidate against hyperglycemia, which may undergo further pharmaceutical development as a hypoglycemic agent.

Fucosylated chondroitin sulfate from Isostichopus badionotus alleviates metabolic syndromes and gut microbiota dysbiosis induced by high-fat and high-fructose diet

Fucosylated chondroitin sulfate from Isostichopus badionotus (fCS-Ib) is a kind of sulfated polysaccharides with well-repeated structure. In our former publications, fCS-Ib has been reported to be a functional food ingredient with hypoglycemic and antilipemic activities. However, there is no systematic study to investigate the effects of fCS-Ib on metabolic syndromes. In the present study, C57BL/6 mice fed on a high-fat and high sucrose diet (HFSD) for 6 weeks was used to cause metabolic syndromes. The final results showed that fCS-Ib alleviated obesity, hyperlipidemia, hyperglycemia, inflammation, liver steatosis, and adipocyte hypertrophy caused by HFSD. Meanwhile, fCS-Ib showed powerful effects on moderating gut microbiota dysbiosis in the HFSD-fed mice. Supplement of fCS-Ib could reduce ratio of Firmicutes to Bacteroidetes by decreasing abundance of Lachnospiraceae and Allobaculum while increasing abundance of Porphyromonadaceae, Barnesiella, and Bacteroides. Our results showed that fCS-Ib could be further developed as a potential pharmaceutical agent to prevent metabolic syndromes and gut microbiota dysbiosis.

Fucosylated chondroitin sulfate oligosaccharides from Isostichopus badionotus regulates lipid disorder in C57BL/6 mice fed a high-fat diet

Fucosylated chondroitin sulfate (fCS) and its depolymerized derivative (DfCS), prepared from sea cucumbers, are well-known for their anticoagulant activity. However, their other functional activities are poorly understood. Recently, we obtained fCS oligosaccharides from Isostichopus Badionotus by a modified controllable Fenton-system, named as DfCS-Ib. The functional activities of these oligosaccharides are still unclear. The present study investigated anti-hyperlipidemic activity of DfCS-Ib using a high-fat diet (HFD)-fed mice model. The results indicated that DfCS-Ib reduced obesity, hyperlipidemia, and inflammation caused by HFD. Meanwhile, DfCS-Ib increased the mRNA expression of PPARγ and decreased the mRNA expression of leptin, aP2, and F4/80 in fat tissue. Transcriptome analysis indicated that DfCS-Ib normalized the expressions of genes regulating lipid metabolism. Our results suggested that DfCS-Ib can alleviated lipid disorder by reducing lipid synthesis and promoting lipid lipidolysis. DfCS-Ib can act as a functional agent to regulate lipid disorder.

Pharmacological Potential of Sea Cucumbers

This review presents a detailed analysis of published research data focused on the pharmacological activity exerted by biologically active compounds isolated from sea cucumbers belonging to the class of Holothuroidea, phylum Echinodermata. The review contains descriptions of the structure, physico-chemical properties and pharmacological effects of these active substances. Particular attention is given to compounds with anticoagulant, antithrombotic, antioxidant, anticancer, anti-infectious, immune-stimulating and anti-ACE (angiotensin converting enzyme) activities as well as to the substances exerting a regulating influence on lipid and carbohydrate metabolism. All these compounds may be considered as prototypes for development of new pharmaceutical substances and medicines.

Airborne PM2.5-Induced Hepatic Insulin Resistance by Nrf2/JNK-Mediated Signaling Pathway

Animal and epidemiological studies have suggested that exposure to airborne particulate matter (PM) with an aerodynamic diameter less than 2.5 μm (PM_2.5) is associated with the risk of developing type 2 diabetes. However, the mechanism underlying this risk is poorly understood. In the present study, we investigated the effects of PM_2.5 exposure on glucose homeostasis and related signaling pathways in mice. Wild-type and nuclear factor erythroid 2-related factor 2 (Nrf2) knockout (Nrf2^−/−) C57BL/6 male mice were exposed to either ambient concentrated PM_2.5 or filtered air (FA) for 12 weeks through a whole-body PM exposure system. At the end of the exposure, we assessed liver damage, and performed metabolic studies, gene expressions, as well as molecular signal transductions to determine the signaling pathways involving oxidative responses, insulin signaling, and glucose metabolism. Our results indicated that PM_2.5 exposure for 12 weeks caused significant liver damage as evidenced by elevated levels of aminotransferase (AST) and alanine aminotransferase (ALT). Furthermore, PM_2.5 exposure induced impaired glucose tolerance and inhibited glycogen synthesis, leading to hepatic insulin resistance indicated by higher glucose levels, higher area under the curve (AUC), and homeostasis model assessment of insulin resistance (HOMA-IR) values. We further found that PM_2.5 exposure significantly increased the expressions of Nrf2 and Nrf2-regulated antioxidant genes. Moreover, PM_2.5 exposure activated the c-Jun N-terminal kinase (JNK) signaling pathway and increased insulin receptor substrate-1 (IRS-1) phosphorylation at Ser³⁰⁷, but reduced protein kinase B phosphorylation at Ser⁴⁷³. Taken together, our study demonstrated PM_2.5 exposure triggered Nrf2-mediated oxidative responses and activated the JNK-mediated inhibitory signaling pathway, resulting in hepatic insulin resistance.

Protective effects of marein on high glucose-induced glucose metabolic disorder in HepG2 cells

BACKGROUND

Our previous study has shown that Coreopsis tinctoria increases insulin sensitivity and regulates hepatic metabolism in high-fat diet (HFD)-induced insulin resistance rats. However, it is unclear whether or not marein, a major compound of C. tinctoria, could improve insulin resistance. Here we investigate the effect and mechanism of action of marein on improving insulin resistance in HepG2 cells.

METHODS

We investigated the protective effects of marein in high glucose-induced human liver carcinoma cell HepG2. In kinase inhibitor studies, genistein, LY294002, STO-609 and compound C were added to HepG2 cells 1h before the addition of marein. Transfection with siRNA was used to knock down LKB1, and 2-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG), an effective tracer, was used to detect glucose uptake.

RESULTS

The results showed for the first time that marein significantly stimulates the phosphorylation of AMP-activated protein kinase (AMPK) and the Akt substrate of 160kDa (AS160) and enhanced the translocation of glucose transporter 1 (GLUT1) to the plasma membrane. Further study indicated that genistein (an insulin receptor tyrosine kinase inhibitor) altered the effect of marein on glucose uptake, and both LY294002 (a phosphatidylinositol 3-kinase inhibitor) and compound C (an AMP-activated protein kinase inhibitor) significantly decreased marein-stimulated 2-NBDG uptake. Additionally, marein-stimulated glucose uptake was blocked in the presence of STO-609, a CaMKK inhibitor; however, marein-stimulated AMPK phosphorylation was not blocked by LKB1 siRNA in HepG2 cells. Marein also inhibited the phosphorylation of insulin receptor substrate (IRS-1) at Ser 612, but inhibited GSK-3β phosphorylation and increased glycogen synthesis. Moreover, marein significantly decreased the expression levels of FoxO1, G6Pase and PEPCK.

CONCLUSIONS

Consequently, marein improved insulin resistance induced by high glucose in HepG2 cells through CaMKK/AMPK/GLUT1 to promote glucose uptake, through IRS/Akt/GSK-3β to increase glycogen synthesis, and through Akt/FoxO1 to decrease gluconeogenesis. Marein could be a promising leading compound for the development of hypoglycemic agent or developed as an adjuvant drug for diabetes mellitus.

1-Deoxynojirimycin Alleviates Liver Injury and Improves Hepatic Glucose Metabolism in db/db Mice

The present study investigated the effect of 1-Deoxynojirimycin (DNJ) on liver injury and hepatic glucose metabolism in db/db mice. Mice were divided into five groups: normal control, db/db control, DNJ-20 (DNJ 20 mg·kg⁻¹·day⁻¹), DNJ-40 (DNJ 40 mg·kg⁻¹·day⁻¹) and DNJ-80 (DNJ 80 mg·kg⁻¹·day⁻¹). All doses were treated intravenously by tail vein for four weeks. DNJ was observed to significantly reduce the levels of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and liver TG, as well as activities of serum alanine aminotransferase (ALT), and aspartate transaminase (AST); DNJ also alleviated macrovesicular steatosis and decreased tumor necrosis factor α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) levels in liver tissue. Furthermore, DNJ treatment significantly increased hepatic glycogen content, the activities of hexokinase (HK), pyruvate kinase (PK) in liver tissue, and decreased the activities of glucose-6-phosphatase (G6Pase), glycogen phosphorylase (GP), and phosphoenolpyruvate carboxykinase (PEPCK). Moreover, DNJ increased the phosphorylation of phosphatidylinositol 3 kinase (PI3K) on p85, protein kinase B (PKB) on Ser473, glycogen synthase kinase 3β (GSK-3β) on Ser9, and inhibited phosphorylation of glycogen synthase (GS) on Ser645 in liver tissue of db/db mice. These results demonstrate that DNJ can increase hepatic insulin sensitivity via strengthening of the insulin-stimulated PKB/GSK-3β signal pathway and by modulating glucose metabolic enzymes in db/db mice. Moreover, DNJ also can improve lipid homeostasis and attenuate hepatic steatosis in db/db mice.

Fucosylated chondroitin sulphate from Cusumaria frondosa mitigates hepatic endoplasmic reticulum stress and inflammation in insulin resistant mice

Endoplasmic reticulum (ER) stress-associated inflammation positively contributes to insulin resistance. It is also known that fucosylated chondroitin sulphate from Cusumaria frondosa (Cf-CHS) can mitigate insulin resistance; however, its effects on ER stress and inflammation are not well understood. Therefore, we investigated whether Cf-CHS-influenced ER stress, inflammatory response and signaling in insulin-resistant mice. Our results showed that Cf-CHS lowered serum and hepatic ROS, NO, and FFA levels. Furthermore, Cf-CHS decreased serum proinflammatory cytokines TNF-α, CRP, MIP-1, IL-1β and IL-6 concentrations as well as their hepatic mRNA expression, and increased the anti-inflammatory cytokine IL-10 levels. Moreover, Cf-CHS reduced the ER stress markers Bip, ATF6, PERK, and XBP1 mRNA or protein expression, and PERK, eIF2α, and IRE1α phosphorylation. These reductions were accompanied by a reduced activation of JNK1 and IKKβ, NFκB nuclear translocation, and IR/IRS-2 serine phosphorylation in Cf-CHS-treated mice. These findings suggested that the Cf-CHS supplementary-induced alleviation of RE stress-associated inflammation could be the mechanism responsible for its beneficial effects against insulin resistance.

Green Synthesis of Oxovanadium(IV)/chitosan Nanocomposites and Its Ameliorative Effect on Hyperglycemia, Insulin Resistance, and Oxidative Stress

In this paper, the preparation, characterization, and ameliorative effect on high-fat high-sucrose diet-induced hyperglycemia, insulin resistance, oxidative stress in mice of novel oxovanadium(IV)/chitosan (OV/CS) nanocomposites were investigated. The nanobiocomposite was produced by chemical reduction by chitosan and L-ascorbic acid using microwave heating, under environment-friendly conditions, using aqueous solutions, and notably, by using both mediators as reducing and stabilizing agents. In addition, OV/CS nanocomposites were characterized by transmission electron microscopy, energy dispersive spectroscopy, particle size, and zeta potential measurements. In vivo experiments were designed to examine whether the OV/CS nanocomposites would provide additional benefits on oxidative stress, hyperglycemia, and insulin resistance in mice with type 2 diabetes. The results rendered insulin resistant by treating with OV/CS nanocomposites alleviate insulin resistance and improve oxidative stress. Such nanocomposite seem to be a valuable therapy to achieve and/or maintain glycemic control and therapeutic agents in the treatment arsenal for insulin resistance and type 2 diabetes.

Ameliorative effect of vanadyl(IV)-ascorbate complex on high-fat high-sucrose diet-induced hyperglycemia, insulin resistance, and oxidative stress in mice

There is mounting evidence demonstrating causative links between hyperglycemia, oxidative stress, and insulin resistance, the core pathophysiological features of type 2 diabetes mellitus. Using a combinational approach, we synthesized a vanadium-antioxidant (i.e., l-ascorbic acid) complex and examined its effect on insulin resistance and oxidative stress. This study was designed to examine whether vanadyl(IV)-ascorbate complex (VOAsc) would reduce oxidative stress, hyperglycemia, and insulin resistance in high-fat high-sucrose diet (HFSD)-induced type 2 diabetes in mice. Male C57BL/6J mice were fed a HFSD for 12 weeks to induce insulin resistance, rendering them diabetic. Diabetic mice were treated with rosiglitazone, sodium l-ascorbate, or VOAsc. At the end of treatment, fasting blood glucose, fasting serum insulin, homeostasis model assessment-insulin resistance index, and serum adipocytokine levels were measured. Serum levels of nitric oxide (NO) parameters were also determined. The liver was isolated and used for determination of malondialdehyde, reduced glutathione, and catalase levels, and superoxide dismutase and glutathione peroxidase activities. VOAsc groups exhibited significant reductions in serum adipocytokine and NO levels, and oxidative stress parameters compared to the corresponding values in the untreated diabetic mice. The results indicated that VOAsc is non-toxic. In conclusion, we identified VOAsc as a potentially effective adjunct therapy for the management of type 2 diabetes.