Oregan Essential Oil: interaction with photogenerated singlet molecular oxygen

DIMARCO PALENCIA, F.C.D; MUÑOZ, V.A; POSADAZ, A.C; CIFUENTE D.A; MISKOSKI S.; FERRARI G.V; GARCÍA N.A; MONTAÑA M.P

Villa Carlos Paz, Córdoba, Argentina

Congreso; XIII LATIN-AMERICAN MEETING ON PHOTOCHEMISTRY AND PHOTOBIOLOGY; 2017

Asociación de fotoquímica y fotobiología

OEO was extracted by hydrodistillation with Clevenger trap from plants grown in the experimental field of the FTU-UNSL, which were in flowering state. The main compounds of OEO, carvacrol (CR) and thymol (TM), were characterized by EIMS and NIST Mass Spectrometry Data Center. In addition, CR and TM were quantified, in the extracted oil, by gas chromatography (see Table 1). The mixture Rf + OEO was irradiated at λ ˃ 400 nm in solvent MeOH: H2O 60:40 v/v and the spectral evolution is shown in the figure, indicating OEO reacts with photogenerated ROS. In order to identify the participating ROS in the photodegradation mechanism of the OEO, experiments of oxygen consumption of solutions in the presence and absence of specific ROS inhibitors were carried out [2]. Oxygen consumption profiles indicate degradation occurs involving singlet molecular oxygen (O2(1Δg)) (see inset). The total quenching rate constant of O2(1Δg), kt, and the reactive quenching constant, kr, of OEO and its two major components were determined (see table). The kr/kt ratio was calculated since it indicates the fraction of overall quenching of O2(1Δg) that effectively leads to a chemical transformation.Table 1. Kinectic constants of OEO, CR and TMSystemkt x 10-6 M-1s-1kr x 10-6 M-1s-1kr/ktTM5.61.70.3CR4.71.10.2OEO4.62.40.5