Insights into the search for new drugs from traditional knowledge: An ethnobotanical and chemical-ecological perspective

Context: The variety of pathways for the introduction of a species into the medical collection of traditional communities has led many researchers to question the processes of selection and the use of these resources. A better comprehension of these processes will allow us to understand the cultural dynamics that are related to traditional medical practices, as well as to provide us with new ways in which to facilitate the exploration of natural products. Objective: This study aims to test the predictive power of the plant apparency hypothesis as it relates to medicinal plant selection by the rural communities of the Caatinga and the Atlantic Forest in northeast Brazil. Material and methods: Initially, a survey of the medicinal plants used by these communities was conducted using semistructured interviews. Subsequently, data on the life strategies and the habits of each species were collected. More detailed data on the specific plant parts indicated in interviews were also collected. A phytochemical screening for seven classes of chemical compounds was carried out to test the predictions of the plant apparency hypothesis. Results: The medicinal plants from the Caatinga (especially those that are considered to be trees in habit) have a strong ability to accumulate quantitative compounds, and these species are most likely to be plants with significant biological activity related to these compounds; the medicinal plants from the Atlantic Forest, on the other hand, tend to have a high occurrence of qualitative compounds, especially in herbaceous life forms. Discussion and conclusion: It was concluded that the plant apparency hypothesis does not adequately explain the selection of medicinal plants in the two environments studied. Our findings highlight some important implications for bioprospecting that need to be further tested experimentally, and through systematic studies, in different regions.