Mono- and polynuclear vanadium(IV) and -(V) compounds with 2-substituted phenyl/pyridyl heterocyclic chelates

Exploring the Biological Effects of Anti-Diabetic Vanadium Compounds in the Liver, Heart and Brain

The prevalence of diabetes mellitus and diabetes-related complications is rapidly increasing worldwide, placing a substantial financial burden on healthcare systems. Approximately 537 million adults are currently diagnosed with type 1 or type 2 diabetes globally. However, interestingly, the increasing morbidity rate is primarily influenced by the effects of long-term hyperglycemia on vital organs such as the brain, the liver and the heart rather than the ability of the body to use glucose effectively. This can be attributed to the summation of the detrimental effects of excessive glucose on major vascular systems and the harmful side effects attributed to the current treatment associated with managing the disease. These drugs have been implicated in the onset and progression of cardiovascular disease, hepatocyte injury and cognitive dysfunction, thereby warranting extensive research into alternative treatment strategies. Literature has shown significant progress in utilizing metal-based compounds, specifically those containing transition metals such as zinc, magnesium and vanadium, in managing hyperglycaemia. Amongst these metals, research carried out on vanadium reflected the most promising anti-diabetic efficacy in cell culture and animal studies. This was attributed to the ability to improve glucose management in the bloodstream by enhancing its uptake and metabolism in the kidney, brain, skeletal muscle, heart and liver. Despite this, organic vanadium was considered toxic due to its accumulative characteristics. To alleviate vanadium's toxic nature while subsequently manipulating its therapeutic properties, vanadium complexes were synthesized using either vanadate or vanadyl as a base compound. This review attempts to evaluate organic vanadium salts' therapeutic and toxic effects, highlight vanadium complexes' research and provide insight into the novel dioxidovanadium complex synthesized in our laboratory to alleviate hyperglycaemia-associated macrovascular complications in the brain, heart and liver.

A Dioxidovanadium Complex cis-[VO2 (obz) py] Attenuates Hyperglycemia in Streptozotocin (STZ)-Induced Diabetic Male Sprague-Dawley Rats via Increased GLUT4 and Glycogen Synthase Expression in the Skeletal Muscle

Vanadium has demonstrated antihyperglycemic effects in diabetes mellitus (DM) but is, however, associated with toxicity. Therefore, new vanadium complexes envisaged to possess heightened therapeutic potency while rendering less toxicity are being explored. Accordingly, the aim of the study was to investigate the effects of a dioxidovanadium (V) complex, cis-[VO2 (obz) py], on selected glucose metabolism markers in streptozotocin (STZ)-induced diabetic rats. STZ-induced diabetic rats were treated orally with cis-[VO2 (obz) py] (10, 20, and 40 mg/kg) twice every 3rd day for 5 weeks. Blood glucose concentrations, body weight, and food and water intake were monitored weekly, for 5 weeks. Rats were then euthanized after which blood, liver, and muscle tissues were collected for biochemical analysis. The administration of dioxidovanadium complex significantly decreased blood glucose concentrations throughout the 5-week period in comparison with the diabetic control (DC). The attenuation of hyperglycemia was accompanied by an increased glycogen concentration in both liver and muscle tissues in the treated groups. Furthermore, a significant increase was observed in the expression of glucose transporter type 4 (GLUT4) in the skeletal muscle tissues and glycogen synthase in the liver tissues. These findings indicate that our vanadium complex cis-[VO2 (obz) py] may exert antihyperglycemic effects through increased glucose uptake, glycogen synthesis, and increased GLUT4 and glycogen synthase expression.

Anti-hyperglycaemic effects of dioxidovanadium complex cis-[VO2(obz)py] avert kidney dysfunction in streptozotocin-induced diabetic male Sprague-Dawley rats

Despite the success of antidiabetic drugs in alleviation of hyperglycaemia, diabetic complications, including renal dysfunction, continue to be a burden. This raises the need to seek alternative therapies that will alleviate these complications. Accordingly, the aim of this study was to investigate the effects of dioxidovanadium(V) complex cis-[VO2(obz)py] on renal function in diabetic rats. Streptozotocin-induced diabetic rats were treated with cis-[VO2(obz)py] (40 mg·kg-1) twice every third day for five weeks. Diabetic untreated and insulin-treated rats served as the diabetic control and positive control, respectively. Blood glucose concentrations, water intake, urinary output, and mean arterial pressure (MAP) were monitored weekly for five weeks. Rats were then euthanized, and blood and kidney tissues were collected for biochemical analysis. Significant decreases in blood glucose concentrations, MAP, glomerular filtration rate (GFR), and SGLT2 expression, as well as plasma angiotensin and aldosterone concentrations, were observed in the treated groups compared with the diabetic control. The complex also increased urinary glucose concentrations, antioxidant enzymes GPx and SOD concentrations, and decreased MDA concentrations and kidney injury molecule (KIM-1) concentrations. These findings suggest that the anti-hyperglycaemic effects of this vanadium complex may ameliorate kidney dysfunction in diabetes.

Heamanetic Effects of a Dioxidovanadium(V) Complex in STZ-Induced Diabetic Male Sprague Dawley Rats

BACKGROUND

Despite the effective maintenance of glucose homeostasis by insulin in type 1 diabetes mellitus, the drug has been implicated as one of the causes of haematological disturbances, which give rise to cardiovascular complications. As a result, research into alternative therapies for diabetes is needed. In our laboratory, an anti-hyperglycaemic novel vanadium complex has been synthesized using organic heterocyclic ligands. The complex has been shown and improve glycaemic control. The effects of this complex on haematological function, however, have not yet been established. Therefore, this study sought to investigate the haematological effects of dioxidovanadium(V) complex in (STZ)-induced diabetic rats.

METHODS

Diabetic rats received vanadium complex (40 mg kg ^-1 p.o), diabetic untreated (H₂O) and insulin treated (0.175 mg kg^-1 s.c), groups acted as a negative and positive control, respectively. Vanadium complex was administered twice daily, and blood glucose concentration was monitored weekly for 5 weeks. Thereafter, the animals were sacrificed followed by blood and kidneys collection for haematological (full blood count and Annexin V), hormonal (EPO) and oxidative status (SOD and GPx) analysis.

RESULTS

After 5 weeks, untreated diabetic rats presented with hyperglycaemia compared to non-diabetic rats which was attenuated by vanadium complex administration. Furthermore, vanadium treated groups presented with an augmented RBC count, haematocrit, haemoglobin concentration, MCHC, MCV, and (EPO) levels compared to diabetic control. An increase in annexin V expression hence cell survival was observed in vanadium complex treated rats. Lastly, the administration of the complex improved antioxidant status as evidenced by increases in SOD and GPx concentration in plasma and in the kidneys.

CONCLUSION

The administration of the anti-hyperglycaemic dioxidovanadium(V) complex improved haematological parameters, cell survival and the antioxidant status displayed by the diabetic rats. These results give an indication that the complex might be an effective alternative therapeutic drug for the treatment of hyperglycaemia in DM.

Cardio-protective effects of a dioxidovanadium(V) complex in male sprague-dawley rats with streptozotocin-induced diabetes

Cardiovascular complications are among the leading causes of morbidity and mortality in diabetes mellitus (DM). Despite the anti-hyperglycemic effects of various anti-diabetic therapeutic agents like insulin, some of these drugs are implicated in precipitating cardiovascular dysfunction. There is therefore an imperative need to seek alternative drugs that may ameliorate these complications. Accordingly, the aim of the study was to investigate the effects of a dioxidovanadium (V) complex, cis-[VO₂(obz)py]) on selected cardiovascular function markers in STZ-induced diabetic rats. The vanadium complex (40 mg kg) was administered orally twice every 3rd day 5 weeks, non-diabetic and diabetic control groups received distilled water whereas the insulin group received subcutaneous insulin injections twice daily for 5 weeks. Blood glucose concentrations, mean arterial pressure (MAP), heart rate, triglycerides (TG) and total cholesterol concentrations were monitored weekly for 5 weeks. Rats were then euthanised and blood and hearts were collected for biochemical analysis. There was a significant decrease in blood glucose, triglycerides, cholesterol concentrations as well as blood pressure of vanadium treated rats compared to the untreated diabetic animals. Vanadium treatment also attenuated cardiac oxidative stress and decreased the expression of transforming growth factor β1 (TGFβ1) and Smad7. Lastly, the administration of the vanadium complex significantly decreased C reactive protein (CRP) and cardiotropin 1(CT-1) concentrations in the plasma and heart tissues. The administration of the dioxidovanadium(V) complex to diabetic rats culminated into cardio-protective effects. Taken together, these observations suggest that this metal complex exhibit a significant potential as an alternative therapeutic drug for DM management.

Complexes containing benzimidazolyl-phenol ligands and Ln(III) ions: Synthesis, spectroscopic studies and preliminary cytotoxicity evaluation

Fourteen new complexes were obtained from Ln(III)(NO₃)₃∙n-H₂O and the chromophores 2-(1H-benzo[d]imidazol-2-yl)-phenol (Bzp1) or 2-(5-methyl-1H-benzo[d]imidazol-2-yl)-phenol (Bzp2). The complete characterization allowed us to assign unequivocally the structures of all the complexes. The techniques used for this purpose were Ultraviolet-Visible (UV-Vis) and Fourier-Transform Infrared (FT-IR) spectroscopies, High-Resolution Mass Spectrometry (HRMS), Magnetic Susceptibility (MS), Elemental Analysis (EA) and Molar Conductivity (MC). HRMS allowed us to find the molecular ion and its isotopic pattern. The FT-IR spectral data suggested that benzimidazolyl-phenol ligands coordinate with Ln(III) ions through iminic nitrogen and phenolic oxygen. Thermogravimetric Analysis (TGA) studies of NdBzp1 and GdBzp2 complexes indicate the presence of lattice water along with three nitrates and two benzimidazolyl-phenol ligands; the thermal decomposition was consistent with the minimal formula suggested by EA. The coordination type of the benzimidazolyl-phenol ligands, the geometry and the structural organization of these coordination complexes have been interpreted by Density Functional Theory (DFT) calculations, and they coincided with the physicochemical data suggesting a coordination number eight for the Ln(III) ions. The cytotoxicity of the chromophores and their coordination complexes was tested against a cancer cell line (HeLa), as compared with structure/support cells (NIH-3T3) and defense cells (J774A.1), revealing that three coordination complexes showed moderate cytotoxicity against the cell lines studied.