Limitations on the ethno-directed approach as a tool for the selection of medicinal plants with antimicrobial activity

Abstract

In this work, we evaluate the antimicrobial properties of three groups of plants selected by the ethnopharmacological method, reported as having antimicrobial and/or anti-inflammatory properties by a rural community in the Brazilian State of Pernambuco. The samples were divided into groups of seven plants reported as having antimicrobial properties (GI), another seven as having anti- inflammatory properties (GII) and eight plants reported to have both (GIII). The antimicrobial properties of these groups were compared using the disc-diffusion method for nine microorganisms: Gram-positive and
Gram-negative bacteria, acid-alcohol resistant bacillus (BAAR) and yeast. Among the samples of GI, 28.6% demonstrated activity against the micro-organisms tested, compared with 57.1% for the GII plants and 100% of GIII. This study shows, then, that the selected species should be looked more carefully that greater care should be taken in selecting species recommended by ethnopharmacological reports for studies of antimicrobial properties, since plants reported to have anti-inflammatory properties may be more active than those reported as being antimicrobial.