Commercial and wild Sicilian Origanum vulgare essential oils: chemical composition, antimicrobial activity and repellent effects

The composition of two different Origanum vulgare essential oils (EOs) was analysed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS); their repellent and antimicrobial effects were evaluated against adults and late-instar larvae of Tribolium confusum and adults of Sitophilus oryzae (Insecta: Coleoptera), Gram-negative and -positive bacteria Pseudomonas fluorescens, Escherichia coli, Staphylococcus aureus, Bacillus cereus and the pathogenic fungi, Penicillium digitatum and Aspergillus flavus. The main constituents of the essential oil from the first sample (obtained by hydrodistillation of inflorescences of wild Sicilian O. vulgare) were thymol and -terpinene wherein main component of the second one (a commercial essential oil) was carvacrol. The two tested oils showed relevant antimicrobial and repellent activity, with variable efficacy depending on chemical composition, concentration, targeted species and exposure time. Based on the obtained results, the study extends knowledge on oregano EOs for their potential use as food protectants during storage.