Antimicrobial activity of Drosophyllum lusitanicum, an endemic Mediterranean insectivorous plant

The aim of this study was to evaluate the antimicrobial activity of Drosophyllum lusitanicum leaf extract against various yeasts and bacteria species, including both standard and clinically isolated strains. The extract exhibited strong antimicrobial activity against all the tested yeast strains with inhibition zones ranging 23.67–42.23mm and with minimum inhibitory concentration (MIC) values ranging 31–63 mgL 1. All the Gram-positive bacteria studied were inhibited by the extract, showing inhibition zones ranging 17.67–43.00mm and MIC values comprising between 15.6 and 250 mgL 1. In contrast, the growth of the tested Gram-negative bacteria was not significantly affected by the extract. Among the microorganisms tested, Staphylococcus epidermidis ATCC 12228 was the most sensitive, presenting the lowest MIC value (15.6 mgL 1), while Enterococcus faecalis ATCC 29212 was the most tolerant (250 mgL 1). The extract of D. lusitanicum was analysed by gas chromatography-mass spectrometry and the major constituent found was plumbagin.Sandra Gonçalves acknowledges a grant from Fundação para a Ciência e a Tecnologia (Grant SFRH/BD/19850/2004