Trembleya laniflora (D. Don) Cogn. (Melastomataceae), Xyris platystachia Alb. Nilss. (Xyridaceae) and Xyris pterygoblephara Kunth., Brazilian species collected from a biodiversity hotspot for conservation priority, had their antimicrobial activity evaluated against standardized strains of Staphylococcus aureus and Micrococcus luteus, by the agar diffusion assay. All extracts, assayed in the concentration of 2000 µg/disc, were active against M. luteus, whereas S. aureus growth was inhibited only by T. laniflora leaves and X. platystachia aerial parts. Fractionation of the extracts by partition between immiscible solvents resulted in active fractions from extracts originally inactive against S. aureus. Activity was mainly found in low and medium polar fractions. The extract of T. laniflora leaves was also fractionated by silica gel column chromatography and both the HPLC fingerprint and antimicrobial activity of the obtained fractions were distinct of those originated from the partition process.
Trembleya laniflora; Xyris platystachia; Xyris pterygoblephara; antimicrobial activity
