Inhibitory effect of essential oils from native Atlantic Forest plants on the growth of Escherichia coli and Bacillus thuringiensis

Abstract

Brazil is a country rich in biodiversity, with the largest plant genetic diversity in the world; Brazilian medicinal plants are considered promising, but there is little knowledge about them from any point of view. Considering the increase in the number of microorganisms resistant to antimicrobial agents available in the market, the need and relevance of studies to find new compounds with antimicrobial activity has arisen. Objective: The present study aimed to evaluate the inhibitory effect of essential oils from Pimenta pseudocaryophyllus and Piper species native to the Atlantic Forest on Gram-negative (Escherichia coli) and Gram-positive (Bacillus thuringiensis) bacteria. Material and Methods: The essential oils were extracted from dried leaves of native plant species by the hydrodistillation method using a graduated Clevenger apparatus with 1 liter of distilled water for 2.5 hours. For the evaluation of the inhibitory effect of the essential oils, the pure oil and the agar diffusion technique were used. Results: The essential oils of the species of the genus Piper did not show promissive results. However, the volatile portion extracted from Pimenta pseudocaryophyllus has shown positive results against the tested bacterial cells. Conclusion: The essential oils from Piper species have no inhibitory effect on Gram-negative bacteria (E. coli), showing antimicrobial activity only on Gram-positive bacteria (B. thuringiensis). On the other hand, the species P. pseudocaryophyllus has a potential antimicrobial action on both bacteria E. coli and B. thuringiensis.