Applied Sciences, Vol. 12, Pages 12641: Experimental and Theoretical Investigations of Argania spinosas Extracts on the Antioxidant Activity and Mild Steel Corrosions Inhibition in 1 M HCl Applied Sciences doi: 10.3390/app122412641 Authors: Hamid Laaroussi Abdelouahad Aouniti Ouafae Mokhtari Baraa Hafez Ryan Adnan Sheikh Manal Y. Sameeh Manal M. Khowdiary Suliman A. Alderhami Ahmed A. Elhenawy Mohamed El Azzouzi Ilyesse Rahhou Chaouki Belbachir Belkheir Hammouti Taibi Ben Hadda Hicham Elmsellem The aim of the present research is the evaluation of the extraction process effect on the chemical composition, the antioxidant activities, and the mild steel corrosion inhibition ability of Argania spinosas extracts (alimentary oil (AO) and hexanic extract of roasted almonds (HERA)). The chemical composition revealed that both extracts have the same major compounds: Palmitic, linoleic, and stearic acids, with their order slightly different. Electrochemical impedance spectroscopy (EIS), weight loss measurements, and polarization curves were used to estimate AO and HERAs mild steel corrosions inhibition capacity. Based on these three methods, AO registered, respectively, 81%, 87%, and 87% inhibition efficiency while HERA registered 78%, 84%, and 82% inhibition efficiency. The antioxidant activity of AO and HERA was examined in parallel with standard antioxidants (gallic acid and quercetin) using two assays: DPPH* scavenging assay and ferric reducing antioxidant power assay (FRAP). AO had less EC50 in both techniques (DPPH*: 3559.08 ± 161.75 μg/mL; FRAP 1288.58 ± 169.21 μg/mL) than HERA (DPPH*: 3621.43 ± 316.05 μg/mL; FRAP 1655.86 ± 240.18 μg/mL). Quantum chemical and molecular dynamic studies were employed to suggest the adsorption mechanism.