Óleo essencial de Lippia sidoides nativas de Minas Gerais: Composição, estruturas secretoras e atividade antibacteriana

Abstract

Given the diverse biological activities presented by essential oils, and the antibacterial potential of the essential oil of Lippia sidoides Cham, the objective of this work was to characterise the essential oil of this species, collected in the southern part of the state of Minas Gerais, Brazil, as well as to identify its secretory structures and evaluate its antimicrobial activity on the phytobacteria, Clavibacter michiganensis subsp. Michiganensis, Xanthomonas vesicatoria and Pseudomonas syringae pv. tomato. Plants were collected in the town of Itumirim, and the essential oils of the leaves extracted by hydrodistillation using a modified Clevenger apparatus. The essential oil presented carvacrol (26.44%) and 1.8-cineole (22.63%) as major constituents. On the leaf surface of L. sidoides both glandular and nonglandular trichomes were found. Among the glandular trichomes are peltate trichomes and type I capitate trichomes. The presence of lipidic and terpenic substances within the head cells of both the peltate and capitate trichomes was found. The essential oil of L. sidoides was able to inhibit the growth of all the microorganisms studied, showing the following MIC: 7.81 ȝg mL-1 for C. michiganensis, 3.9 ȝg mL-1 for P. syringae and 15.62 ȝg mL-1 for X. vesicatoria. Carvacrol, the major constituent, showed MIC values equal to 3.9 ȝg mL-1 for all three bacteria studied. Both exhibited the ability to inhibit the growth of gram-positive and gram-negative bacteria.