Estudo bioprospectivo de plantas comercializadas para fins terapêuticos em mercados públicos da Região Nordeste do Brasil

Abstract

This bioprospective study with an ethno-directed approach took into consideration the knowledge of vendors of medicinal plants in a region of Northeast Brazil known as Triângulo Crajubar. Our aim was to survey the plants sold for therapeutic purposes in public markets in the area studied, to select the plant species based on ethnopharmacological use and to analyze them for phytochemical composition and antibacterial and antiparasitic activities. Medicinal plant vendors were asked to fill out a questionnaire to determine the relative importance of the species and informant consensus factor. Ninety-one species were indicated as being therapeutically useful; they were distributed in 49 families and 89 genera. Thirteen species showed great versatility in their use. There were 291 indications of use in 13 disease categories. On the basis of these results, the plant species Operculina hamiltonii, Cephaelis ipecacuanha and Lippia gracilis were selected and evaluated as follows, according to their ethnopharmacological use. The infusion of O. hamiltonii (IOh) and decoction of C. ipecacuanha (DCi) were analyzed by HPLC-DAD, while the chemical composition of the essential oil of L. gracilis (OELG) was determined by gas chromatography coupled to mass spectrometry. IOh was tested in vitro for epimastigote and promastigote susceptibility and cytotoxicity. IOh, DCi and OELG were subjected to broth microdilution assays to determine the minimal inhibitory concentration against bacteria; solutions of the natural products were also tested at subinhibitory concentrations to evaluate them for antibiotic resistance-modifying activity. O. hamiltonii showed high leishmanicidal and trypanosomicidal activities, but also substantial cytotoxicity. O. hamiltonii and C. ipecacuanha did not exhibit satisfactory antibacterial activity, but assays for modulatory potential demonstrated interesting results with synergism observed using various combinations of antibiotics and natural products. OELG was able to modulate bacterial resistance and could be used as a coadjuvant therapy against multidrug-resistant microrganisms.