Medicinal plants for the "nerves": a review of ethnobotanical studies carried out in South Brazil

ABSTRACT Among the medicinal purposes for which plants have been used is the treatment of “nerves". The objective of this study was to search for species of plants used in the state of Rio Grande do Sul (South Brazil) for the relief of symptoms related to central nervous system (CNS) disorders. Twenty-seven ethnobotanical studies were compiled, in which a total of 94 species were cited. The five most cited species were Cymbopogon citratus (81.5 %), Melissa officinalis (77.7 %), Aloysia citriodora (66.6 %), Matricaria chamomilla (62.9 %) and Passiflora edulis (51.8 %). Scientific studies have corroborated the popular use of these plants as sedatives, but most studies are preclinical and very few have been clinical (M. chamomilla and M. officinalis), and these were mainly exploratory or were performed against placebo. In addition to efficacy data, there are also indications of toxicity for M. chamomilla and P. edulis. In conclusion, there is a great diversity of plant species used in the treatment of symptoms related to CNS disorders, and they are most frequently used as a sedative. Data indicate that M. officinalis possesses clinical efficacy in the treatment of symptoms associated with anxiety without signs of toxicity.