Influence of Phenological Stage on the Volatile Content and Biological Properties of Origanum elongatum Essential Oil

Origanum elongatum (OE) is an aromatic, medicinal plant endemic to Morocco that is widely used in traditional medicine due to its biological properties. This study aimed to elucidate the chemical composition of the essential oil (EO) obtained from O. elongatum (OEEO) at three stages of its life cycle, including vegetative stage (OEEO-VS), flowering stage (OEEO-FS), and post-flowering (OEEO-PFS), as well as to evaluate its biological and antiradical characteristics. The chemical analysis of the essential oil was conducted using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was evaluated in vitro through distinct methodologies, namely, disc diffusion and microatmosphere assay; subsequently, the minimum inhibitory concentration (MIC) was then determined. The antioxidant potential was also measured by using the DPPH and FRAP assays. The GC-MS revealed the predominant of p-cymene (26.83%_31.45%), γ-terpinene (8.46%_26.95%), thymol (13%_29.54%), and carvacrol (20.25%_37.26%), in all three samples, with notable variations according to the phenological stage of the samples. The EOs extracted at three phenological stages demonstrated notable antibacterial efficacy against all the phytopathogen tested. The MICs for Erwinia amylovora exhibited a range of 6.25 and 250 µg/mL. However, for Agrobacterium tumefaciens C58 and Allorhizobium vitis S4, the MICs spanned 125 and 250 µg/mL. In the DPPH test, the IC50 values were 168.25 ± 1.14, 147.01 ± 0.78, and 132.01 ± 2.06 µg/mL for EOs derived from the vegetative, flowering, and post-flowering period, respectively. In the FRAP test, the EC50 values were 164.22 ± 1.04, 215.73 ± 1.48, and 184.06 ± 0.95 µg/mL for the same stages. The findings offer promising prospects for the phytochemical development, demonstrating how the phenological stage significantly influences the therapeutic and biotechnological potential of O. elongatum. This has the potential to open up new avenues of research in the pharmaceutical, agronomic, and environmental fields.