Extraction, Chemical Composition and in vitro Antibacterial Activity of the Essential Oil of Lippia origanoides Kunth from Northeast Brazil

Lippia origanoides Kunth has among its synonyms Lippia sidoides Cham. and is popularly known as 'alecrim-pimenta' or 'rosemary pepper'. Essential oil of L. origanoides (EOLO) has been previously reported for several biological activities without significant acute toxicity, even at higher doses. In this study, essential oil (EO) was extracted from dried leaves, inflorescences, and branches of L. origanoides from Limoeiro do Norte, Ceara, Brazil by hydrodistillation at 3.63% (w/w) yield. Posteriorly, the presence of chemical compounds in the EOLO was identified by gas chromatography coupled to mass spectrometry (GC-MS). The analysis allowed to identify the thymol as the main metabolite (83.53%), followed by p-cymene (5.92%), caryophyllene (4.31%), gamma-terpinene (3.27%), thymol methyl ether (1.18%), beta-myrcene (1.00%), and alpha-terpinene (0.79%). The minimal inhibitory concentration (MIC) of EOLO was assessed against Gram-negative and Gram-positive bacterial pathogens such as Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus. At 10 mu L/mL concentration, the EOLO exhibited antibacterial activity against all the tested bacterial pathogens, and this concentration was considered as the MIC. The minimum bactericidal concentration (MBC) of EOLO was assessed at the MIC concentration, which inhibited the complete growth of all tested bacterial pathogens after 3 h. Therefore, concentrations less than 10 mu L/mL were set as MBC. Thus, our findings suggest that the EOLO can be used as a promising antibacterial agent in the industries.

Automated summary

This study analyzed the essential oil of Lippia origanoides from Brazil and identified thymol as the main compound. The essential oil exhibited antibacterial activity against various bacterial pathogens, suggesting its potential as a promising antibacterial agent.