As a corrosion inhibitor for mild steel in a molar hydrochloric acid medium, we investigated the potential of Eucalyptus globulus essential oil (EuEO). Through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves, and theoretical methods, including DFT/B3LYP 6-31G (d, p) and Monte Carlo simulations, the interactions between the EuEO components and the steel surface were analyzed. D-Allose, Betulinaldehyde, and Uvaol were identified as the major active compounds in the GC-MS analysis. The experimental results showed that EuEO reached an inhibitory efficiency as high as 97% at a 1 g/L concentration. The findings suggest that EuEO operates as a mixed-type inhibitor, reducing both cathodic and anodic reactions, as well as building up a protective coating on the steel surface. Simulations also confirmed that EuEO molecules function as electron donors and acceptors, enhancing corrosion resistance.

Background/Objectives: The phytochemical composition, antioxidant, and antibacterial properties of Vitex agnus-castus L. essential oil (VACEO), extracted from fruit harvested in the Middle Atlas region of Morocco, were investigated. Methods/Results: A full chemical analysis of VACEO was performed to identify the principal components of the oil using GC–MS, demonstrating that caryophyllene (13.87%), 1-(4-Isopropylphenyl)-2-methylpropyl acetate (12.20%), and τ-Cadinol (5.41%) were the most important constituents of this oil. In addition, antioxidant activity was evaluated using DPPH, FRAP, TAC, and beta-carotene bleach tests; the oil demonstrated an IC50 of 0.93 ± 0.03 mg/mL (DPPH), an EC50 of 0.146 ± 0.004 mg/mL (FRAP), and a total antioxidant capacity of 0.794 ± 0.02 mg BHT equivalent/g EO, with relative antioxidant activity at 72.69 ± 0.3%. Antibacterial assays revealed inhibition diameters ranging from 13.25 ± 1.00 mm to 21.11 ± 0.25 mm, with minimum inhibitory concentrations (MICs) ranging from 0.02–0.04 mg/mL against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa. Moreover, ADMET analysis suggested VACEO potential for drug development, with specific insights into pharmacokinetics, safety, and molecular docking, clarifying its interactions with key bacterial proteins. Conclusions: These results confirm the promising therapeutic and pharmaceutical potential of VACEO through its bioactive compounds.