title: Comparative study of the antimicrobial activity of native and exotic plants from the Caatinga and Atlantic Forest selected through an ethnobotanical survey.
abstract: BACKGROUND
  The idea that many commonly used medicinal plants may lead to the discovery of new drugs has encouraged the study of local knowledge of these resources.
  
  
  OBJECTIVE
  An ethnobotanical survey of species traditionally used for the treatment of infectious diseases was undertaken in two areas of northeastern Brazil: one in the Caatinga (dry forest) and another in the Atlantic Forest (humid forest).
  
  
  METHODS
  Initially, diffusion tests using paper disks and subsequently, for extracts presenting significant results (inhibition halos above 15 mm), minimum inhibitory concentrations were determined. The activity was evaluated as a percentage for each species, comparing the diameters of the inhibition halos and the number of positive results against the seven microorganisms studied. Extracts were classified into three categories: strong activity-species with halos exceeding 16 mm, moderate activity-species with halos between 13 mm and 15 mm and low activity-species with halos below 12 mm. We selected 34 species, 20 from the Caatinga and 14 from the Atlantic Forest.
  
  
  RESULTS
  In the Caatinga, 50% of the 20 plant extracts studied had strong antimicrobial activity, 25% had moderate activity and 15% had low activity. In the Atlantic Forest, 28.5% of the 14 plant extracts studied showed strong activity, with 14.5% having moderate activity and 28.5% having low activity. The microorganism that was most susceptible to the extracts from the Caatinga, was Mycobacterium smegmatis; 85% of the species tested were able to inhibit its growth. The organism that was susceptible to the highest number of plant species (71%) from the Atlantic Forest was Staphylococcus aureus.
  
  
  CONCLUSIONS
  Extracts from the Caatinga showed a trend of superior antimicrobial activity compared to the species from the Atlantic Forest, in terms of both inhibiting a greater variety of microorganisms and demonstrating higher activity against susceptible strains.
authors.affiliation: Departamento de Biologia, Laboratório de Etnobotânica Aplicada, Universidade Federal Rural de Pernambuco, Brasil.
authors.forename: Cecília de Fátima
authors.initials: Cde F
authors.lastname: Castelo Branco Rangel de Almeida
authors.forename: Daniela Lyra
authors.initials: DL
authors.lastname: de Vasconcelos Cabral
authors.forename: Camila Castelo Branco
authors.initials: CC
authors.lastname: Rangel de Almeida
authors.forename: Elba Lúcia
authors.initials: EL
authors.lastname: Cavalcanti de Amorim
authors.forename: Janete Magali
authors.initials: JM
authors.lastname: de Araújo
authors.forename: Ulysses Paulino
authors.initials: UP
authors.lastname: de Albuquerque
mesh_terms: D000890:Anti-Infective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001938:Brazil; D055808:Drug Discovery; D019448:Ethnobotany; D008519:Medicine, Traditional; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D010936:Plant Extracts