Essential Oil of Origanum vulgare var. aureum L. from Western Romania: Chemical Analysis, In Vitro and In Silico Screening of Its Antioxidant Activity

This investigation aims to assess the chemical composition and antioxidant properties of Origanum vulgare var. aureum L. essential oil (OEO). The oil was obtained with a 0.34% (v/w dried weight) yield and investigated by gas chromatography-mass spectrometry (GC-MS) analysis. The main compounds of the OEO were found to be gamma-terpinene (22.96%), para-cymene (14.72%), germacrene (11.64%), beta-trans-ocimene (9.81%), and cis-beta-ocimene (7.65%). Furthermore, individual antioxidant assays 1,1-diphenyl-2-picrylhydrazyl (DPPH) and [2,2 '-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium] (ABTS) radical scavenging activities and beta-carotene/linoleic acid bleaching were carried out. OEO demonstrated better scavenging effects on the DPPH (IC50 93.12 +/- 0.03 mu g/mL) and ABTS (IC50 27.63 +/- 0.01 mu g/mL) assays (significantly lower IC50 values; p <= 0.001) than ascorbic acid (IC50 127.39 +/- 0.45 mu g/mL). In the beta-carotene/linoleic acid bleaching assay, the OEO exhibited a higher Relative antioxidant activity (RAA %) (82.36 +/- 0.14%) but lower compared with butylated hydroxyanisole (BHA) (100%), with no significant differences (p > 0.05) observed. According to molecular docking results, the first two main compounds of the OEO, para-cymene, and gamma-terpinene, may potentially contribute to the biological antioxidant activity of the oil by inhibiting ROS (reactive oxygen species)-producing enzymes such as lipoxygenase and xanthin oxidase. These experimental data suggest that OEO could represent a valuable new natural antioxidant source with functional properties in the food or pharmaceutical industries.