Lippia graveolens HBK oleoresins, extracted by supercritical fluids, showed bactericidal activity against multidrug resistance Enterococcus faecalis and Staphylococcus aureus strains

Objective The aim of this work was to characterize Lippia graveolens oleoresins, obtained by Supercritical Fluid Extraction (SFE), from crops collected at different locations in Mexico. The antimicrobial effect of oleoresins was tested in reference strains and clinical isolates of susceptible and multidrug resistant (MDR) strains of Enterococcus faecalis and Staphylococcus aureus. Significance The increasing of MDR strains is becoming a global public health problem that has led to the search for new treatments, and essential oils have resurged as a source of compounds with bactericidal functions. Oregano essential oil has attracted attention recently, however, this oil is mainly obtained by hydro-distillation (uses large amounts of water) or solvents extraction (potential contaminant). SFE has gained popularity as it represents an environmentally friendly technology. Methods L. graveolens oleoresins were obtained by SFE, total phenol contents were quantified by Folin-Ciocalteu method, the identification of compounds and thymol and carvacrol quantification was carried out by GC-MS. The antimicrobial activity was tested by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results SFE showed higher yields compared with the hydro-distillation process. L. graveolens grown in different Mexican locations showed differences in oleoresin composition and a slightly different antimicrobial capacity against clinical isolates. Conclusions It was demonstrated that SFE is an efficient technology for extracting L. graveolens oleoresins. Additionally, the solvent-free extraction method and the observed antimicrobial effect, increases the applications of these oleoresins in fields such as cosmetics, food industry, medicine, amongst others.