Phenolic Profile, Antioxidant, and Antibacterial Activities of Extracts and Essential Oils of Algerian Artemisia herba-alba and Thapsia garganica

Artemisia herba-alba and Thapsia garganica are two of the most famous and potent medicinal plants used in Algeria. This study aimed to investigate the phenolic profile, antioxidant, and antibacterial activities of extracts and essential oils of Artemisia herba-alba (AH) and Thapsia garganica (TG). The plant samples were extracted using four solvents with different polarities, while essential oils were obtained by the hydrodistillation method. Phytochemical screening was performed to identify various secondary metabolites present in the extracts. Total phenol, flavonoid, and tannin contents were determined following standard methods. Furthermore, the antioxidant activity was evaluated using FRAP and β-carotene bleaching assays. The antibacterial activity of the extracts and essential oils was evaluated by the agar well diffusion, and the disc diffusion assays, respectively. The results confirmed the richness of these plants in tannins (content ranging from 20.47 to 239.02 µg TAE/mg E) and flavonoids (1.47 to 83.89 µg QE/mg). The best ferric reducing antioxidant capacity was exhibited by the acetone extracts for both plants (A = 1.90 for AH extract and A = 0.83 for TG extract). The extracts prevented lipid peroxidation in vitro, with AH methanol extract exhibiting the highest activity with percentage inhibition of 90.01%. Furthermore, AH and TG extracts and essential oils exhibited good antibacterial activity against E. coli, S. aureus, and P. aeruginosa with inhibition zone diameters ranging from 9.5 to 20 mm. On the basis of these findings, AH aerial parts and TG roots appear to be good sources of bioactive compounds with antioxidant and antibacterial activities.