Revalorizing ancient herbs in Egyptian modern deserts: A functional study on Origanum syriacum essential oils

• Cultivated and produced oregano ( Origanum syriacum ) in the newly reclaimed desert region of Wadi El Natrun, Egypt, promoting sustainable agricultural practices as an alternative to the limited natural habitat in the St. Catherine Nature Reserve, Sinai, Egypt. • Conducted comprehensive studies on the extraction of oregano three essential oils (i.e. Leaves EO, Stems EO, and Aerial parts of the plant EO), including their physical properties and chemical composition. • Evaluated the antioxidant activity of the three essential oils by 5 different methods, highlighting their role as high-value natural antioxidants with potential applications in food, pharmaceutical, and cosmetic industries. This study investigates the potential of Origanum syriacum L., a plant native to Egypt’s Saint Catherine Sinai nature reserves, as a natural source of phytochemicals. For the first time, this species was successfully cultivated under desert conditions on the American Egyptian Lebanese Company for Herbs (AELC) Farm in the Wadi El Natrun region. Essential oils were extracted from the plant’s leaves, stems, and aerial parts and subsequently analyzed for yield, physical properties, and chemical composition. The antioxidant activity of the oils was evaluated using five different assays: DPPH (expressed as % inhibition and IC₅₀), FRAP (reported as TEAC in mmol/L), ferrous ion-chelating (FIC % inhibition), TBARS (expressed as % inhibition and IC₅₀), and the Rancimat method (as Antioxidant Activity Index, AAI). The results revealed a high essential oil yield, with GC-MS analysis identifying 20, 18, and 19 chemical compounds in aerial part of the plant,leaves, and stems, respectively, predominantly thymol and carvacrol. Interestingly, the stems exhibited a higher thymol content, whereas the leaves showed nearly equal concentrations of thymol and carvacrol. All samples demonstrated significant antioxidant activity across all tested methods, highlighting the plant’s potential as a valuable source of natural antioxidants.