A new approach to study medicinal plants with tannins and flavonoids contents from the local knowledge

The present work tested the power of different methodological strategies for identifying plants that could be interesting in terms of their phenolic compounds (especially flavonoids and tannins) by comparing a new index in which priority-determining criteria are based on the free-listing technique as well as on two randomized methods for choosing plants within an ethnodirected based approach. The present study was undertaken in the rural area of the municipality of Altinho located in the central region of Pernambuco State, northeastern Brazil. The ethnobotanical survey was divided into three different stages. The first stage was a general survey of 101 individuals on the use and knowledge of medicinal plants within the community. During the second stage local specialists were selected on the basis of the quality and quantity of information they offered during the initial phase of the investigation. The third stage consisted of returning to the specialists a final time in order to apply the free-listing technique. We also assumed that a plant could demonstrate anti-inflammatory and healing effects even without the presence of the compounds of interest of this study. There is a strong association between tannin content and the effects popularly attributed to wound-healing and anti-inflammatory plants. No relationships were observed between plants used by the community to treat inflammation or healing with their flavonoid contents. Thus, identifying Caatinga medicinal plants known with anti-inflammatory activity and healing capacities is a good criterion for identifying species with high levels of tannins, although these same criteria are not useful for identifying plants with high flavonoid contents.