Volatile compound profile and essential oil composition of three wild Algerian aromatic plants with their antioxidant and antibiofilm activities

Aromatic plants represent a natural source of bioactive compounds. Even their essential oils attracted the interesting of many researchers for their biological activities. Therefore, the aims of this work were to analyze the volatile (aroma) compounds of three wild Algerian plants (Thymus algeriensis, Origanum glandulosum and Eucalyptus globulus) and determinate the composition of their essential oils (EO) by HS-SPME-GC/MS and GC-FID/GC–MS technics, respectively. Followed by evaluation of the antioxidant activity of the studied essential oils by five complementary methods. MICs determination and antibiofilm activity of these essential oils were determined against six pathogenic microorganisms. The main compound for T. algeriensis aroma and EO was thymol with 50.15% and 70.58%, respectively. Whereas carvacrol with percentage of 35.60% and 33.97% was the major component in O. glandulosum aroma and EO, respectively. In the case of E. globulus aroma, α-pinene (26.21%), p-cymene (24.45%), 1,8-cineole (22.80%) were the major compounds, but 1,8-cineole (17.93%), p-cymene (16.08%) and p-cymen-8-ol (15.55%) were the dominated constituents in EO. Essential oil of T. algeriensis exhibited highest antioxidant activities in ABTS·⁺ and CUPRAC assays with IC₅₀ values of 9.95 ± 0.17 and 29.21 ± 0.74 µg/mL, respectively. Essential oils allowed antibiofilm effects agains all tested strains with low MICs. Particularly, essential oil of T. algeriensis showed the lowest MICs (0.078–1.25 µL/mL) for all tested microorganisms. According to these results, T. algeriensis and O. glandulosum could be used as bioresource of thymol and carvacrol respectively by pharmaceutic industry. Also, the studied essential oils can be exploited as naturel antipathogenic and antioxidant agents alone or like additives.