Urban ethnobotany: open-air fairs in the State of Rio de Janeiro, Brazil, as a potential source of new antitubercular plants

Ethnobotany and Ethnopharmacology have been used as a strategy to select plants that can result in the development of new drugs. This study aims to relate the medicinal plants traded in open-air fairs in Rio de Janeiro State, popularly used to treat tuberculosis. Ethnobotanical techniques were used among the sellers and Salience Index was calculated. As a result from the interviews, 36 plant species were listed belonging to 12 families. Plants indicated for tuberculosis with a higher Salience value were Erva-de-passarinho (Struthanthus marginatus and S. concinnus) and Assapeixe (Vernonia spp.). The ethanol extracts of these three species were assayed in vitro against susceptible (H₃₇Rv) and resistant (35338) M. tuberculosis with Minimum Inhibitory Concentration (MIC) values ranging from 25 to 200µg/ml. From the active fractions, phytol, lupeol, 3-O-n-acil-lup-20(29)-en-3β,7β,15α-triol (Struthanthus marginatus) and taraxerol, obtusifoliol and phytol (S. concinnus) were isolated. This study demonstrated the importance of ethnobotanical surveys in open-air markets as a source for the research of new drugs and scientific validation of popular use.