Quercetin (QT) as a bioactive flavonoid has a potential therapeutic activity for numerous neuronal injuries and neurodegenerative diseases. However, the low absorption rate of QT, especially through the blood-brain barrier, restricts its bioactivity in the body. The current research took the advantage of superparamagnetic iron oxide nanoparticles (SPIONs) to enhance the bioavailability of quercetin. Quercetin conjugated with SPIONs was prepared by means of nanoprecipitation method and was characterized by X-ray diffractometer, scanning electron microscope, and Fourier transformed infrared spectrometer analyses. Wistar male rats were orally fed by gavage with QT and QT-SPION at 50 and 100 mg/kg daily doses for 7 days. Using high-performance liquid chromatography (HPLC) method, biodistribution of QT was evaluated in plasma and brain tissue. The outcomes of this research revealed a higher concentration in the plasma and brain of the rats fed with QT-SPION in comparison to free QT. The results of this study confirm that SPION as a targeted drug delivery system enhances the bioavailability of quercetin in the brain about ten folds higher than free quercetin and could be used for the treatment of neurodegenerative disorders.

Cadmium is a heavy metal that causes oxidative stress and has toxic effects in humans. The aim of this study was to investigate the influence of two probiotics along with a prebiotic in preventing the toxic effects of cadmium in rats. Twenty-four male Wistar rats were randomly divided into four groups namely control, cadmium only, cadmium along with Lactobacillus plantarum (1 × 109 CFU/day) and inulin (5% of feedstuff) and cadmium along with Bacillus coagulans (1 × 109 spore/day) and inulin (5% of feedstuff). Cadmium treated groups received 200 μg/rat/day CdCl2 administered by gavage. During the 42-day experimental period, they were weighed weekly. For evaluation of changes in oxidative stress, the levels of some biochemicals and enzymes of serum including SOD, GPX, MDA, AST, ALT, total bilirubin, BUN and creatinine, and also SOD level of livers were measured at day 21 and 42 of treatment. The cadmium content of kidney and liver was determined by using atomic absorption mass spectrophotometry. Data were analyzed using analysis of variance (ANOVA) followed by Duncan’s post hoc test. Treatment of cadmium induced rats with synbiotic diets significantly improved the liver enzymes and biochemical parameters that decreased AST, ALT, total bilirubin, BUN and metal accumulation in the liver and kidney and increased body weight, serum and liver SOD values in comparison with the cadmium-treated group. No significant differences were observed with MDA and GPX values between all groups (p > 0.05). This study showed that synbiotic diets containing probiotics (L. plantarum and B. coagulans) in combination with the prebiotic (inulin) can reduce the level of cadmium in the liver and kidney, preventing their damage and recover antioxidant enzymes in acute cadmium poisoning in rat.