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

BORDÓN, ANAHÍ; RODRÍGUEZ, S. A.; CUTRO, ANDREA C.; HOLLMANN, AXEL

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

Tagetes minuta L., popularly known as Chinchilla, is a native South American plant thathas been used for different applications, including traditional medicine forantispasmodics, antiseptics, and stomach disorders, among others. It has been reportedthat the essential oil (EO) obtained from T. minuta shows interesting biological activities asan antifungal, antiviral, antibacterial, and insecticide. In this context, the objectives of thiswork were to obtain by hydrodistillation the EO from the leaves of this species located inSantiago del Estero, and characterize its chemical composition and antibacterial action.The chemical profile was determined by gas chromatography coupled with massspectrometry, indicating that the major components of the EO were dihydrotagetone,ocimene, and tagetone. The minimal inhibitory concentrations (MIC) and minimalbactericidal concentrations (MBC) against gram-positive S. aureus ATCC 252923 andgram-negative E. coli ATCC 252922 were obtained. This EO has shown a MIC of 10 μg/mLand 20 μg/mL for S. aureus and E. coli, respectively. On the other hand, CBM has onlybeen observed in E. coli at the maximal concentration tested, 20 μg/mL. By fluorescencemicroscopy studies, it has been shown that after 24 h of incubation with this EO, leadpermeability changes in the membranes of both bacteria at the MIC concentration. Thisfact indicates that the bacterial membrane represents an important target for theantimicrobial action observed. In this sense, the change in melting transition temperature(Tm) by dynamic scattering light and laurdan fluorescence polarization (GP) by the actionof EO in the biomimetic membrane system, liposomes of DMPC and DMPG (5:1) weredetermined. The EO-membrane interaction reduces the Tm and the cooperativeinteraction between phospholipid chains and decreases the laurdan GP. These resultsindicate that the EO is capable of affecting the membrane, increasing fluidity and theaccess of molecular water, confirming that the bacterial membrane is one of the targetsfor the antibacterial action.