Antibacterial Action of T. Minuta Essential Oil: Insights into Membrane Effects

ANAHÍ BORDÓN; RODRIGUEZ, SERGIO A.; ANDREA C. CUTRÓ; HOLLMANN, AXEL

cORDOBA

Congreso; LI Reunión Anual de la Sociedad Argentina de Biofísica; 2023

Sociedad Argentina de Biofísica

Tagetes minuta L., popularly known as Chinchilla, is a native South American plant that hasbeen used for different applications, including traditional medicine for antispasmodics,antiseptics, and stomach disorders, among others. It has been reported that the essential oil(EO) obtained from T. minuta shows interesting biological activities as an antifungal,antiviral, antibacterial, and insecticide. In this context, the objectives of this work were toobtain by hydrodistillation the EO from the leaves of this species located in Santiago delEstero, and characterize its chemical composition and antibacterial action. The chemicalprofile was determined by gas chromatography coupled with mass spectrometry, indicatingthat the major components of the EO were dihydrotagetone, ocimene, and tagetone. Theminimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC)against gram-positive S. aureus ATCC 252923 and gram-negative E. coli ATCC 252922were obtained. This EO has shown a MIC of 10 µg/mL and 20 µg/mL for S. aureus and E.coli, respectively. On the other hand, CBM has only been observed in E. coli at the maximalconcentration tested, 20 µg/mL. By fluorescence microscopy studies, it has been shown thatafter 24 h of incubation with this EO, lead permeability changes in the membranes of bothbacteria at the MIC concentration. This fact indicates that the bacterial membrane representsan important target for the antimicrobial action observed. In this sense, the change in meltingtransition temperature (Tm) by dynamic scattering light and laurdan fluorescencepolarization (GP) by the action of EO in the biomimetic membrane system, liposomes ofDMPC and DMPG (5:1) were determined. The EO-membrane interaction reduces the Tmand the cooperative interaction between phospholipid chains and decreases the laurdan GP.These results indicate that the EO is capable of affecting the membrane, increasing fluidityand the access of molecular water, confirming that the bacterial membrane is one of thetargets for the antibacterial action.Keywords: Tagetes minuta L, essential oil, antibacterial, biophysical characterization, meltingtransition temperature, laurdan polarization.