Parkinson’s disease (PD) is the second most common neurodegenerative disease in the world. Neurodegeneration of the substantia nigra (SN) and diminished release of dopamine are prominent causes of this progressive disease. The current study aims to evaluate the protective potential of ethanolic extract of Mentha piperita (EthMP) against rotenone-mediated PD features, dopaminergic neuronal degeneration, oxidative stress and neuronal survival in a mouse model. Swiss albino male mice were assigned to five groups: control (2.5% DMSO vehicle), PD (rotenone 2.5 mg/kg), EthMP and rotenone (200mg/kg and 2.5mg/kg, respectively), EthMP (200 mg/kg), and Sinemet, reference treatment containing levodopa and carbidopa (20 mg/kg and rotenone 2.5mg/kg). Behavioral tests for motor functional deficit analysis were performed. Anti-oxidant capacity was estimated using standard antioxidant markers. Histopathology of the mid-brain for neurodegeneration estimation was performed. HPLC based dopamine level analysis and modulation of gene expression using quantitative real-time polymerase chain reaction was performed for the selected genes. EthMP administration significantly prevented the rotenone-mediated motor dysfunctions compared to PD group as assessed through open field, beam walk, pole climb down, stepping, tail suspension, and stride length tests. EthMP administration modulated the lipid peroxidation (LPO), reduced glutathione (GSH), and superoxide dismutase (SOD) levels, as well as glutathione-s-transferase (GST) and catalase (CAT) activities in mouse brain. EthMP extract prevented neurodegeneration in the SN of mice and partially maintained dopamine levels. The expression of genes related to dopamine, anti-oxidant potential and synapses were modulated in M. piperita (MP) extract treated mice brains. Current data suggest therapeutic capacities of MP extract and neuroprotective capacities, possibly through antioxidant capacities. Therefore, it may have potential clinical applications for PD management.

Quercetin is a well-known flavonoid that resents in fruits and vegetables. Zinc oxide nanoparticles (ZnO-NPs) are widely used for packing and cosmetics. This study was conducted to determine the effect of Quercetin on the liver by ZnO-NPs toxicity in a mouse model. Thirty-six Swiss albino mice were divided into two groups, i.e. control group and the experimental group. The control group was administered saline for 28 days orally. The experimental group is further divided into three groups. To the first one, only ZnO-NPs (30 mg/kg, orally) were given for 28 days. To the second group, only quercetin (100 mg/kg, orally) was given for 28 consecutive days. To the third, a combination of quercetin and ZnO-NPs was given for alternate 28 days through the oral route. Animals were sacrificed after 14 and 28 days of dosing. Mouse liver was fixed in the 10% formalin to preserve organ integrity. Histopathological analysis was done to observe the structure of liver in treated mice. The ZnO-NPs group shows the central vein full of infiltrations, sinusoidal spaces congestions and some the necrosis of hepatocytes was observed. The quercetin group shows a normal central vein with no infiltrations. The animals that received both quercetin and ZnO-NPs showed infiltration in central vein and necrosis but less than that of only ZnO-NPs given group. Full recovery in the liver structure was observed in the quercetin+ZnO-NPs group after 28 days of treatment. This study showed the hepatoprotective effect of quercetin because it reduces the toxicity produced by ZnO-NPs.