Nitroxide derivatives for imaging of hypercholesterolemia-induced kidney dysfunction and assessing the effectiveness of antilipidemic drugs

Safety evaluation of saffron extracts in early and established atherosclerotic New Zealand white rabbits

Previous research has shown that natural medications pose health risks, especially in subjects with comorbidities. This study aimed to evaluate the safety of saffron ethanolic extract (SEE) administration in early and established atherosclerotic rabbits. Rabbits were given a high-cholesterol diet (HCD) for 4 and 8 weeks to induce early and established atherosclerosis respectively, and then they were treated with 50 and 100 mg/kg/day SEE. The body weight of the animals was recorded. Blood samples were collected at baseline, pre-treatment, and post-treatment for hematological studies, lipid profiles, and biochemical profiles. Tissue specimens of the vital organs were subjected to histological examination. The above parameters were significantly altered post-intervention with 4 and 8 weeks of HCD. No significant differences in body weight were observed in all the groups post-treatment with 50 and 100mg/kg of SEE compared to pre-treatment. However, low-density lipoprotein cholesterol, total cholesterol, serum urea, and glucose significantly decreased post-treatment with 50 and 100mg/kg/day SEE compared to pre-treatment in early and established atherosclerosis groups. Hematological parameters that were affected post-intervention with HCD returned to their baseline values post-treatment with 50 and 100mg/kg/day SEE. There was a significant improvement in the vital organs post-treatment with 50 and 100mg/kg SEE. SEE can safely be administered without causing harmful effects on the hematological, biochemical profiles, and vital organs. Notably, SEE exerts hypolipidemic and hypoglycemic effects on atherosclerotic conditions. Further clinical trials are warranted to ensure the safety of saffron administration in patients with atherosclerosis-related diseases.

Nitroxyl Radical as a Theranostic Contrast Agent in Magnetic Resonance Redox Imaging

Significance:In vivo assessment of paramagnetic and diamagnetic conversions of nitroxyl radicals based on cyclic redox mechanism can be an index of tissue redox status. The redox mechanism of nitroxyl radicals, which enables their use as a normal tissue-selective radioprotector, is seen as being attractive on planning radiation therapy. Recent Advances:In vivo redox imaging using nitroxyl radicals as redox-sensitive contrast agents has been developed to assess tissue redox status. Chemical and biological behaviors depending on chemical structures of nitroxyl radical compounds have been understood in detail. Polymer types of nitroxyl radical contrast agents and/or nitroxyl radical-labeled drugs were designed for approaching theranostics. Critical Issues: Nitroxyl radicals as magnetic resonance imaging (MRI) contrast agents have several advantages compared with those used in electron paramagnetic resonance (EPR) imaging, while support by EPR spectroscopy is important to understand information from MRI. Redox-sensitive paramagnetic contrast agents having a medicinal benefit, that is, nitroxyl-labeled drug, have been developed and proposed. Future Directions: A development of suitable nitroxyl contrast agent for translational theranostic applications with high reaction specificity and low normal tissue toxicity is under progress. Nitroxyl radicals as redox-sensitive magnetic resonance contrast agents can be a useful tool to detect an abnormal tissue redox status such as disordered oxidative stress. Antioxid. Redox Signal. 36, 95-121.

Chia seeds oil enriched with phytosterols and mucilage as a cardioprotective dietary supplement towards inflammation, oxidative stress, and dyslipidemia

Introduction: Non-communicable diseases are a cluster of metabolic diseases, which include type-2 diabetes, cancer, and cardiovascular diseases (CVDs). The aim of the current research was to incorporate dietary fibers (mucilage) and phytosterol for enriching chia seeds oil for producing new dietary supplements for cardio-protection from oxidative stress, inflammation, and dyslipidemia. Methods: Fatty acids profile, phytosterols, and phenolic compounds content of the prepared dietary supplement were assessed. The cardioprotective potency of the dietary supplement was evaluated in rats fed on a high-fat diet for a month. Biochemical parameters related to inflammation, oxidative stress, lipid profile, cardiac enzymes, and kidney function were determined in all rats. Results: The results revealed that dietary supplement was rich in omega-3 fatty acids. Beta-sitosterol and campesterol were the major phytosterols in chia seeds oil dietary supplement. Phenolic compounds were present by 25.9 ± 1.202 mg gallic acid equivalent (GAE)/g dietary supplements. Rats fed on the high-fat diet showed significant elevation (P < 0.05) in inflammatory markers, oxidative stress, dyslipidemia, and cardiac enzymes in association with the elevation of kidney function compared with normal rats. Administration of both doses of dietary supplement significantly (P < 0.05) improved all the studied biochemical parameters. The high dose of the dietary supplement was promising in the reduction of inflammatory markers, oxidative stress, and improved dyslipidemia in accordance with the reduction of all cardiac enzymes and kidney function. Conclusion: Dietary supplements investigated in the current research showed cardioprotective potency through its anti-inflammatory and dyslipidemic activities, which may be attributed to the presence of phenolic compounds, omega-3 fatty acids, phytosterols, and soluble dietary fibers.

Effects of oxygen challenging to tissue redox and pO2 status

Nitroxide free radicals can serve as redox-sensitive MRI contrast agents useful to image the redox status of tissue of interest. In this study, the effect of oxygen content in the inspired gas on the kinetics of metabolism of three nitroxides has been evaluated in the muscle and tumor in mice. SCC tumors (approximate size of 1.0 cm³) on the right hind leg of female C3H/Hen MTV^- mice were prepared. Three nitroxides, 3-carboxy-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CxP), 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CmP), and 4-hydroxy-tetramethylpiperidine-N-oxyl (TEMPOL), having different lipophilicities were compared using MR redox imaging. T₁-mapping of the tissues was obtained using a multi-slice multi-echo (MSME) sequence with several TRs. The three nitroxides showed differences in accumulation and metabolism/clearance in muscle and tumor. The cell impermeable nitroxide CxP displayed kinetic patterns of slow enhancement followed by a slow decline typical of clearance rather than metabolism. The cell permeable CmP on the other hand showed a relatively faster uptake and metabolism with a modestly higher rate of metabolism in the tumor than muscle. The TEMPOL on the other hand displayed a rapid uptake and reduction with a trend of significantly rapid decay rate in tumor tissue, while slightly higher maximum signal intensity and slower decay rate was observed in normal muscle. The reduction rate of TEMPOL in the tumor was significantly enhanced when the breathing gas had 100%-oxygen while it was not significantly different in the muscle. EPR oximetry studies monitoring the oxygen dependent linewidth of TEMPOL showed that the pO₂ in the healthy tissue during carbogen breathing significantly increased normal tissue pO₂ compared to air breathing whereas breathing 100%-oxygen made normal tissue slight hypoxic. Since TEMPOL is a radioprotector, our studies show that a combination of 100%-oxygen breathing and TEMPOL has a potential to enhance radioprotective effects to normal tissue.

The effect of cholesterol overload on mouse kidney and kidney-derived cells

Introduction: Dyslipidemia is one of the onset and risk factors of chronic kidney disease and renal function drop is seen in lipoprotein abnormal animal models. However, the detailed molecular mechanism of renal lipotoxicity has not been clarified. Therefore, the present study aimed to investigate the influence of cholesterol overload using mouse kidney tissue and kidney-derived cultured cells.

Methods: C57BL/6 mice were fed normal diet (ND) or 1.25% cholesterol-containing high-cholesterol diet (HCD) for 11 weeks, and we used megalin as a proximal tubule marker for immunohistology. We added beta-very low density lipoprotein (βVLDL) to kidney-derived cells and examined the effect of cholesterol overload on megalin protein and mRNA expression level, cell proliferation and cholesterol content in cells.

Results: In the kidney of HCD mice, the gap between glomerulus and the surrounding Bowman’s capsule decreased and the expression level of megalin decreased. After βVLDL treatment to the cells, the protein expression and mRNA expression level of megalin decreased and cell proliferation was restrained. We also observed an increase in cholesterol accumulation in the cell and free cholesterol/phospholipid ratios increased.

Conclusions: These findings suggest that the increased cholesterol load on kidney contribute to the decrease of megalin and the overloaded cholesterol is taken into the renal tubule epithelial cells, causing suppression on cell proliferation, which may be the cause of kidney damage.