Parkinson’s disease is one of the most common neurodegenerative diseases. Animal models have contributed a large part to our understanding and therapeutics developed for treatment of PD. There are several more exhaustive reviews of literature that provide the initiated insights into the specific models; however a novel synthesis of the basic advantages and disadvantages of different models is much needed. Here we compare both neurotoxin based and genetic models while suggesting some novel avenues in PD modelling. We also highlight the problems faced and promises of all the mammalian models with the hope of providing a framework for comparison of various systems.

Alzheimer’s disease (AD) is characterized by depositions of amyloid β (Aβ) peptides aggregates resulting in plaques formation in the central nervous system (CNS). This study evaluates the disease-modifying potential of scopoletin against multiple factors associated with AD such as cholinesterase enzymes, Aβ peptides, and neuroprotective properties against Aβ- and H₂O₂-induced cytotoxicity under in vitro conditions. Scopoletin was identified and quantified using UPLC-QTOF (ultra-high performance liquid chromatography-quadrupole time-of-flight) and high-performance liquid chromatography (HPLC), respectively. The antiamyloidogenic potential was evaluated by thioflavin T and congo red binding assay. Inhibition of key enzymes, that is, acetylcholinesterase and butyrylcholinesterase, was investigated by Ellman’s assay. UPLC-QTOF analysis showed that most abundant phytoconstituent present in Argyreia speciosa hydroalcoholic root extract was scopoletin followed by festuclavine and ergometrine. Scopoletin was further quantified using novel reverse phase (RP)-HPLC method developed in this study. The neuroprotective potential of scopoletin was found to be 69% against Aβ42-induced neurotoxicity and 73% against H₂O₂-induced cytotoxicity in PC12 cell culture at 40 μM final concentration. At the same concentration, scopoletin inhibited Aβ42 fibril formation up to 57%. The IC₅₀ concentration for AChE and BuChE enzyme inhibition by scopoletin was 5.34 and 9.11 μM, respectively. The antiaggregation and enzyme inhibition results were complemented with strong molecular interactions of scopoletin with target proteins validated by in silico molecular docking analysis. Based on this study, it can be concluded that scopoletin can be used as a lead for amelioration of symptoms and disease-modifying effects in AD.

Oxidative damage caused by free radicals plays an important role in the causation and progression of many diseases, including aging. Free-radical damage is countered by many mechanisms, including both active antioxidant enzymatic activity in our body and passive antioxidants. Antioxidant response of our body can accommodate increased oxidative damage in diseased states to a level but beyond that level, additional antioxidants are required to combat the increased stress. Apart from the regular dietary sources of antioxidants, many traditional herbal medicines demonstrate a potential to boost antioxidant activity. Rasayana chikitsa that deals with rejuvenation and revitalization is a branch of the Indian traditional medical system of ayurveda. We review some select herbs described in rasayana chikitsa that have been assessed by modern means for stimulating intrinsic antioxidant responses in humans. A critical evaluation of rasayana chikitsa will likely provide urgently needed, actual stimulants of our physiological antioxidant responses and not just more passive antioxidants to add to an already large catalog.

There is accumulating evidence showing that hyperglycemia conditions like diabetes possess a greater risk of impairment to the neuronal system because high glucose levels exacerbate oxidative stress, accumulation of amyloid-beta peptides, and mitochondrial dysfunction, and impair cognitive functions and cause neurodegeneration conditions like Alzheimer’s diseases. Due to the extensive focus on pharmacological intervention to prevent neuronal cells’ impairment induced by hyperglycemia, the underlying molecular mechanism that links between Diabetes and Alzheimer’s is still lacking. Given this, the present study aimed to evaluate the protective effect of piperine on streptozotocin (STZ) induced hyperglycemia and candidate gene expression. In the present study, rats were divided into four groups: control (Vehicle only), diabetic control (STZ only), piperine treated (20 mg/kg day, i.p), and sitagliptin (Positive control) treated. The memory function was assessed by Morris water maze and probe test. After treatment, biochemical parameters such as HOMA index and lipid profile were estimated in the serum, whereas histopathology was evaluated in pancreatic and brain tissue samples. Gene expression studies were done by real-time PCR technique. Present data indicated that piperine caused significant memory improvement as compared to diabetic (STZ) control. The assessment of HOMA indices in serum samples showed that piperine and sitagliptin (positive control, PC) caused significant alterations of insulin resistance, β cell function, and insulin sensitivity. Assessment of brain and pancreas histopathology shows significant improvement in tissue architecture in piperine and sitagliptin treated groups compared to diabetic control. The gene expression profile in brain tissue shows significantly reduced BACE1, PSEN1, APAF1, CASPASE3, and CATALASE genes in the piperine and sitagliptin (PC) treated groups compared to Diabetic (STZ) control. The present study demonstrated that piperine not only improves memory in diabetic rats but also reduces the expression of specific AD-related genes that can help design a novel strategy for therapeutic intervention at the molecular level.

Parkinson’s disease remains as one of the most common debilitating neurodegenerative disorders. With the hopes of finding agents that can cure or reduce the pace of progression of the disease, we studied two traditional medicinal plants: Centella asiatica and Withania somnifera that have been explored in some recent studies. In agreement with the previous work on ethanol extracts of these two plants in mice model, we saw an improvement in oxidative stress profile as well as behavioral performance in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson-like symptoms in Balb/c mice. Given the known potential of both the herbal extracts in improving Parkinson-like symptoms, we expected the combination of the two to show better results than either of the two but surprisingly there was no additivity in either oxidative stress or behavioural recovery. In fact, in some assays, the combination performed worse than either of the two individual constituents. This effect of mixtures highlights the need of testing mixtures in supplements market using enthomedicine. The necessity of comparing multiple groups in this study to get most information from the experiments motivated us to design a ladder-like visualization to show comparison with different groups that we call complete comparison display (CCD). In summary, we show the potential of Centella asiatica and Withania somnifera to ameliorate Parkinson’s disorder.