Evaluation of the Antioxidant Activity and the Antibacterial Potential of Dittrichia viscosa (L.) against Nosocomial Pathogens

Dittrichia viscosa (L.) Greuter, a Mediterranean medicinal plant widely used in traditional medicine, is renowned for its wealth of phytochemical and therapeutic potential. This study aimed to investigate the antioxidant activity and antibacterial potential of Dittrichia viscosa aerial parts and roots against nosocomial pathogens. The antibacterial activity was assessed against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains using the disc diffusion and microdilution assays. The antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP), and total antioxidant capacity (TAC) assays.  The extracts demonstrated strong antibacterial activity, particularly against Staphylococcus aureus and Escherichia coli, with minimum inhibitory concentration (MIC) ranging from 0.1562 to 5.0 µg/mL. Most of the extracts exhibited bactericidal effects, with minimum bactericidal concentration (MBC) equating the MIC for certain strains. Among the extracts, the decoction demonstrated the strongest antioxidant capacity, with IC50 values of 15.68 ± 0.07 µg/mL, 36.32 ± 1.09 µg/mL, and 83.29 ± 13.89 µg/mL in the DPPH, ABTS, and FRAP assays, respectively, along with a TAC value of 12.40 ± 1.23 mg AAE/g extract. These results underline the ability of the plant to neutralize free radicals and reduce oxidative stress effectively. The dual antibacterial and antioxidant activities of D. viscosa highlight its potential as a natural source of bioactive compounds for pharmaceutical applications. These findings position D. viscosa as a promising candidate for developing therapies targeting oxidative stress and multidrug-resistant infections, addressing the growing demand for alternative and sustainable treatment options.