Evaluation of antimicrobial activity of essential oils from the Brazilian plants Acritopappus confertus, Cuphea carthagenensis and Poiretia bahiana

The present work aimed to evaluate the antimicrobial activity the essential oils (EO) of Poiretia bahiana, Acritopappus confertus and Cuphea carthagenensis from Chapada Diamantina (Bahia, Brazil). In a first approach, the EO effects were tested at a concentration range from 1000 to 4000 ppm, on the yeast Saccharomyces cerevisiae, the gram negative bacteria Escherichia coli and the gram positive bacteria Bacillus subtilis, both in an agar diffusion assay and in liquid culture medium. The EO of P. bahiana displayed a fungistatic and a fungicidal effect on S. cerevisiae and a bacteriostatic effect on E. coli and B. subtilis. The EO of A. confertus only displayed bacteriostatic effect on B. subtilis, whilie the EO of C. carthagenensis had no effect on the microorganisms tested. The yeast S. cerevisiae was identified as the most sensitive microorganism to the tested EOs and the P. bahiana EO was the most active. Further studies using this EO and S. cerevisiae wild type, as well as several mutants, showed that the EO induced the production of ROS and, although, the mitochondria doesn't appear to be the main location of ROS production, it has a determinant role on the cells capacity to remove these radicals. The results also suggest that Sod1 enzyme is essential to protect the cell from oxidative stress caused by EO, while Sod2 p and Ctt1 p have a less relevant role. EO of P. bahiana induced a programmed yeast cell death process, apparently apoptotic and mediated by Aac1/2/3 p and Aif1 p. On the contrary, Pep4 p and Yca1 p appear not to be involved in the death process.

Acknowledgements: This work was supported by Fundação para a Ciência e Tecnologia (FCT), projects PTDC/AGR-ALI/105169/2008, and PEst-OE/AGR/UI4033/2014.