Identificação química e atividade antimicrobiana de óleos essenciais das folhas de Piper marginatum obtidos em meio ácido, básico e neutro

Abstract

The increasing resistance of pathogenic microorganisms to conventional antimicrobials has been faced as a worldwide public health problem. The generalized use of antimicrobials in the treatment of infections caused by pathogens indulges microbial resistance, rendering them ineffective. The search for new plant compounds becomes an innovative alternative as an excellent source of new bioactive molecules. This work aims to define the chemical composition, as well as to evaluate the antimicrobial activity of essential oils of Piper marginatum leaves in basic, acid and neutral environments. The collection of plant material was made in the reserve dois irmãos located in the city of Recife on the campus of the Universidade Federal Rural de Pernambuco (UFRPE). The essential oils extracted from Piper marginatum leaves were obtained by hydrodistillation technique, using Clevenger type apparatus and the identification of their chemical constituents were determined by GC-MS. To obtain the oil in acidic environments an acidic solution of sulfuric acid: nitric acid in the molar ratio (1: 1) was prepared, as well as to obtain in basic environments a basic solution of potassium hydroxide was prepared at a concentration of 5 Mol.L-1. Antimicrobial activity was evaluated using the MIC method (Minimum Inhibitory Concentration). The results showed that the oil obtained in acid environments had a better activity against gram-negative E. coli bacteria with a MIC of 78.1 μg/ml and the fungi C. Albicans and C. Utilis with a MIC of 312 μg/ml and 78.1 μg/ml respectively. The activities of oils in basic and neutral environments were considered moderate to weak for all microorganisms tested, and showed MIC ranging from 625 μg/ml to 2500 μg/ml for both oils. Regarding the identification of the constituents, the major compounds found in the oils obtained in the basic and neutral environments were Macrocarpene, and Z Asarone, respectively. These results contribute to the chemical and biological knowledge of P. Marginatum, which is widely publicized as an excellent plant for therapeutic purposes.