Much attention has been recently given to the effect of diet compounds on physical and mental health. Gallic acid is a phenolic compound with antioxidant activity. This compound is widely presented in black tea leaves, green tea, apples, grapes, strawberries, and pineapples. During the past years, it has been reported that gallic acid is effective against nervous system’s disorders including Alzheimer’s disease, Parkinson’s disease, ischemia, and reperfusion, depression and anxiety. These indicate that gallic acid can be considered as a valuable agent for nutraceutical interventions. In this study, several clinical studies suggested that gallic acid can improve human health by preventing or delaying the onset of neurological diseases. The present study indicated the neuroprotective features of gallic acid including the pre-clinical evidence for its effects in AD and PD and other diseases related to the nervous system. Significant efforts are required to confirm the neuroprotective effects of gallic acid in treating the diseases related to the nervous system.

Context: Parkinson’s disease (PD) is a neurodegenerative disorder due to gradual loss of dopaminergic nerves in the substantia nigra (SN) in the midbrain. PD leads to certain motor disorders including resting tremor, muscle stiffness and slow movement. Medicinal plants have shown positive pharmacological effects in treating different models of PD. Objective: Tendency to use natural products, especially plants, for the treatment of PD has been growing. This article reviews the basic aspects of medicinal plants and their bioactive compounds that could be used to treat PD. Methods: Reliable articles indexed in databases ISI, SID, PubMed, PubMed Central, Scopus and Web of Science were used. A total of 12 plant-derived active ingredients and 18 herbal extracts were included. Different compounds have so far been isolated from plants that affect PD especially by targeting pathways associated with the pathogenesis of the disease. Results: Although some herbal extracts such as Hibiscus asper Hook. f. (Malvaceae), Ginkgo biloba L. (Ginkgoaceae), Carthamus tinctorius L (Asteraceae) and certain active ingredients, such as berberine and curcumin, have shown positive effects in animal models of PD, potential active ingredients and mechanisms of action should be investigated in additional studies. Discussion and conclusions: Despite the wide variety of plants in the world, a limited number of them have been studied for anti-Parkinsonian activity, and therefore, there are numerous perspectives in this field for future studies on plants and their bioactive compounds.