Potential antiparkinsonian agents derived from South African medicinal plants

Many natural products and medicinal plants have been tested experimentally for validation of their reported folkloric efficacies. South Africa has abundant plant biodiversity and medicinal plants are still widely used in most parts of the country for the treatment of common neurodegenerative disorders (NDDs). However, very few studies have reported on the validation of South African medicinal plants (SAMPs) used in traditional, complementary and alternative medicine (TCAM) for the treatment of NDDs. Extensive testing provides the basis for clinical trials which progressively lead to the development of affordable, indigenous and readily available products for preventing or treating NDD including Parkinson's disease (PD), one of the most common central nervous system (CNS) disorders among the elderly often characterized by the progressive loss of dopaminergic neurons (DNs) or dopamine-producing cells in the substantia nigra of the midbrain. In this study, several databases were searched to identify active compounds in SAMPs known to potentially protect neurons from progressive damage as seen in most NDDs. Our search results showed many commonly used SAMPs and their possible mechanisms of action including prevention of neuronal death by inhibition of Caspase-3 activation, MAO-B enzyme inhibition as well as restoration of glutathione content in cells. Most of the observed effects relate to the protection of DNs from degeneration, indicating the potential use of these compounds as antiparkinsonian agents. This review article therefore identifies and presents research gaps on how indigenous SAMPs could be studied more extensively for their chemical constituents and bioactivity against age-related NDDs such as PD.