Potencial antimicrobiano e antioxidante de óleos essenciais obtidos de diferentes genótipos de Lippia gracilis Schauer

Abstract

Due to the increasing demand for new compounds with applicability in medicine, the food industry, pharmacology, and therapeutics, the use of essential oils has gained prominence in recent years. These compounds possess chemical properties that allow their application in different areas of biotechnology. Based on this, the aim of the present study was to evaluate the antimicrobial and antioxidant activities of essential oils from different genotypes of Lippia gracilis Schauer, as well as to apply a predictive model to analyze the microbial growth kinetics of pathogenic strains exposed to different pH conditions (5.0, 6.0, and 9.0), essential oil concentrations (1.32, 2.64, and 5.29 mg/mL), and pH + essential oil combinations. Antimicrobial activity was assessed using the disk diffusion method, Minimum Inhibitory Concentration (MIC), and Minimum Bactericidal Concentration (MBC). Most strains showed high to extremely high sensitivity to the oils. Pseudomonas aeruginosa was the only bacterium not sensitive. MIC and MBC values ranged from 1.32 to 42.37 mg/mL. Antioxidant activity was determined using the ABTS method (656.2–1,185.0 μmol Trolox/L), FRAP method (1,296.8–2,656.2 μmol Trolox/L), and DPPH method (314.6–446.6 μmol Trolox/L). In the predictive experiments, the essential oil that showed the lowest MIC and MBC values against most bacteria was used. In treatments varying only oil concentrations, no growth was observed for most strains. Furthermore, the combination of pH + essential oil was effective in inhibiting or reducing bacterial growth rate and prolonging the lag phase duration. Overall, L. gracilis essential oils demonstrated excellent potential for application as natural antioxidants and antimicrobial agents.