Chemical composition of Minthostachys setosa (Briquet) and Piper elongatum (Vahl) essential oils, antistaphylococcal activity and effect on Staphylococcus aureus biofilm removal

Minthostachys setosa (Briquet) (M. setosa) and Piper elongatum (Vahl) (P. elongatum), known as muña and matico, respectively, are plants originating from Peru. They are widely used in a variety of traditional uses, such as food preservatives, digestives, antispasmodics, carminatives, insecticides, and antibacterials. This study was conducted to determine the chemical composition of M. setosa and P. elongatum essential oils (EOs), as well as to evaluate their antistaphylococcal activity and effect on the removal of preformed biofilm by Staphylococcus aureus on stainless steel. Gas chromatography/mass spectrometry revealed pulegone (57.54%) and caryophyllene (7.29%) as the most abundant compounds of M. setosa essential oil (EO), while eucalyptol (10.84%) and methyl eugenol (9.29%) were the main compounds of P. elongatum EO. Both EOs showed antistaphylococcal activity and the ability to remove preformed S. aureus biofilm on stainless steel at two temperatures (25 and 37 °C). A reduction of up to 2.52 CFU.log cm-2 was observed in S. aureus viable cell counts in preformed biofilm, which was concentration- and isolate-dependent. Confocal laser scanning microscopy demonstrated that M. setosa and P. elongatum EOs presented activity on the preformed S. aureus biofilm. Significant reductions in the count of viable cells in the biofilm were observed as the concentrations of EOs increased. In conclusion, pulegone and eucalyptol, respectively, were the main compounds found in the EOs of M. setosa and P. elongatum. These EOs demonstrated antistaphylococcal activity and the potential to remove S. aureus biofilms on surfaces commonly found in the food industry.