Evaluation of the therapeutic properties of a Ruthenium(ll) uracil-derived diimine complex on selected complications associated with diet-induced pre-diabetes.

Abstract

Pre-diabetes is a chronic metabolic condition where blood glucose levels are above the upper threshold considered normal but below the threshold for a diagnosis of diabetes. Pre-diabetes predisposes individuals to a high probability of future progression to overt T2DM. Pre-diabetic patients are at increased risk of developing other pathologies such as NAFLD, diabetic nephropathy (DN) and immune dysregulation complications. As a chronic disease, the long-term implications of diabetes contribute to poor quality of life and significantly increase costs associated with healthcare. Pre-diabetes may however be reversible, through the implementation of lifestyle modification programmes based around dietary modification and increased physical activity. Where lifestyle modifications are ineffective, both pharmacotherapy and lifestyle modification are recommended. However, there is reported poor patient compliance in terms of dietary intervention as patients tend to heavily rely on the pharmacological treatment, thus reducing the efficacy of the drug and increasing the possibility to develop T2DM. Hence, there is a need for novel drugs that will remain therapeutic even in the absence of dietary modification. In our laboratory, we have synthesized a novel ruthenium(II) uracil-derived diimine complex that has been shown to improve insulin sensitivity and restore glucose homeostasis in diet-induced prediabetes. In this study, we further sought to evaluate the effects of this compound on selected complications associated with diet-induced pre-diabetes. Estimating whether ruthenium(II) uracil-derived diimine complex in both the presence and/or absence of dietary intervention will show to be effective in the management of prediabetic-related complications. A high fat high carbohydrate (HFHC) diet was used to induce pre-diabetes for 20 weeks. After the induction, pre-diabetic rats were randomly allocated to the following treatment groups: non-prediabetes (NPD); pre-diabetic (PD); metformin plus HFHC; metformin plus normal diet (ND); Ruthenium plus HFHC and ruthenium plus ND. The animals were treated with subcutaneous injection of ruthenium complex (15 mg/ kg) and oral dose of metformin (500 mg/ kg). The rats were treated once a day every third day at 09:00 am for 12 weeks. Every 4 weeks, parameters such as body weight, food intake, fasting blood glucose, fluid intake and urinary output were monitored for 12 weeks treatment period. In study 1, the administration of ruthenium(II) complex resulted in the restoration of liver and body weights in the pre-diabetic treated rats when compared to the PD group. This treatment also reduced liver damage enzyme biomarkers and plasma total bilirubin

levels in the pre-diabetic treated rats when compared to the PD group whilst administration of ruthenium(II) with dietary intervention reduced plasma sterol regulatory element binding protein 1c (SREBP-1c) concentration in the pre-diabetic treated rats when compared to the PD group. These findings were further supported by the histological analysis of the liver, showing reduced hepatic lipid droplet accumulation, hepatocyte ballooning and locular disarray in the ruthenium(II)-treated rats when compared to the PD group as seen in chapter 2 of the study. In study 2, the administration of ruthenium(II) complex resulted in reduced blood glucose, aldosterone, fluid intake and urinary output in the pre-diabetic treated rats when compared to the PD group which positively correlated with a restoration in plasma and urinary electrolytes along with plasma antioxidants concentrations in the ruthenium(II)-treated rats. Furthermore, there was a decrease in kidney injury molecular-1 (KIM-1) concentration, albumin excretion rate (AER) albumin creatinine ratio (ACR) and mRNA expression of podocin in urine in the ruthenium(II)-treaded rats. These observetions were further demonstrated by the histological analysis of the kidney, displaying improved histology of renal glomerulus in ruthenium-treated rats when compared to the PD group as seen in chapter 3 of the study. In study 3, treatment with ruthenium(II) complex resulted in reduction of platelet activation markers mean platelet volume (MPV) and CD40 Ligand (CD40 L) concentrations, which positively correlated with decreased plasma triglycerides (TG) and very low-density lipoproteins (VLDL) levels in the pre-diabetic treated rats when compared to the PD group. Whilst administration of ruthenium(II) with dietary intervention reduced plasma fibrinogen concentration in the pre-diabetic treated rats when compared to the PD group. These was further evidenced by normalization of immune cell counts in the ruthenium(II)-treated rats. Furthermore, there was a decrease in pro-inflammatory cytokines, tumor necrosis factor α (TNF-α) concentration in the ruthenium(II)-treated rats and decreased interleukin-1β (IL-1β) concentration in the ruthenium(II) with dietary interventiontreated rats when compared to the PD group as seen in chapter 4 of the study. Taken together, the results observed suggest that ruthenium(II) complex exhibited hepato and renoprotective effects while ameliorating immune dysregulation underlying pre-diabetes in diet-induced pre-diabetic rats. However, further studies are still required to find out the exact mechanism behind potential effect of this metal-based compound.