SOUTH AFRICAN MEDICINAL PLANTS USED TO TREAT MENTAL ILLNESS

The majority of the population in South Africa use traditional health care to treat various mental conditions. Only a small number of the more than 300 southern African plant species reported to treat or affect the CNS have been scientifically evaluated and very few of the active compounds have been isolated and identified. Ethnobotanical information on plants used by the traditional healers in southern Africa to treat mental illnesses, specifically epilepsy, depression, age-related dementia and debilitative mental disorders will be highlighted. Details of the recent pharmacological studies conducted on some of these plants, including screening results from several in vitro and in vivo bioassays, as well as the isolation and identification of active compounds will be presented. Several plants have exhibited potential antidepressant activity by binding to the serotonin re-uptake transporter in the [3H]-citalopram binding assay. This includes the observed serotonin re-uptake inhibitory activity and acetylcholinesterase (AChE) inhibitory activity of several South African Amaryllidaceae alkaloids. Inhibitors of AChE are important in the symptomatic treatment of Alzheimer’s disease. The ability of southern African medicinal plants to inhibit monoamine oxidase, an important enzyme in the metabolism of several neurotransmitters, has the potential to lead to new treatments for Parkinson’s disease. Several plants have shown probable sedative or anticonvulsant activity by binding to the GABAA/benzodiazepine receptor. Active compounds in this and other assay, such as biflavones from Searsia (= Rhus) species, will be discussed. Acknowledgements: National Research Foundation (NRF, Pretoria), University of KwaZulu-Natal