Chemical composition and modulation of antibiotic activity of essential oil of Lantana caatingensis M. (Verbenaceae)

This study reports for the first time on the chemical composition, toxicity and antibacterial activity of the of Lantana caatingensis essential oil (LcEO), a medicinal plant from Northeastern Brazil. The essential oils were analyzed by GC-MS, GC-FID and NMR. The quantitative analysis of the anti-staphylococcal activity was carried out by determining their percentage inhibition degree. From the chemical constituents of the essential oil analyzed, we observed a high proportion of sesquiterpene hydrocarbons, being the β-caryophyllene and bicyclogermacrene its main representatives. The toxicity evaluation was performed on Artemia salina with results considered active (LC50 < 100 μg/mL). The antimicrobial activity was evaluated separately and in association of aminoglycoside antibiotics with LcEO by microdilution method. The results indicated that LcEO can be an alternative source of natural products with antibacterial action, being capable of inhibiting the bacteria Staphylococcus aureus with MIC values ​​of 64 μg/mL. The combination of LcEO with aminoglycoside antibiotics against S. aureus showed significant synergism, with 75% reduction in the concentration to the MIC value of amikacin.