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This article is part of the contribution to the development of two medicinal plants widely used by the Moroccan population: white wormwood (Artemisia herba-alba) andArâr (Juniperus phoenicea), species belonging to the Asteraceae and Cupressaceae families, respectively. The present work was conducted to investigate the chemical composition and anticorrosive properties of essential oils (EOs) extracted from these plants. The chemical analysis of the essential oils (EOs) was carried out by GC-MS/MS. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and quantum chemical calculations by density-functional theory at B3lYP were used to study the anticorrosive effect of the researched oils on mild steel in 1 M hydrochloric acid solution. Moreover, SEM-EDX analysis was used to identify the surface morphology of mild steel surface. GC-MSMS results showed the presence of 32 potentially active compounds in the EOs of Artemisia herba-alba. The average yield of the EOs was about 1.39 ± 0.17 mL/100 g dry matter. Beta thujone (30.07%) and alpha thujone (13.32%) are the main components, while for the EOs of Juniperus phoenicea, the study showed the presence of 30 constituents, with alpha-pinene (43.61%) and manoyl oxide (11.5%) as the main components. The average yield of HE was 1.10 ± 0.03 mL/100 g dry matter. The findings demonstrated an important anticorrosive action of EOs from Artemisia herba-alba and Juniperus phoenicea. Notably, the experimental results showed good efficiency of the studied essential oils and correlated well with the density-functional theory (DFT) calculations. The results of potentiodynamic polarization measurements showed that hydrazone acted as a mixed-type inhibitor. The EIS results showed an increase in charge transfer resistance accompanied by a noticeable decrease in Cdl values, revealing that both studied oils were effective as reliable inhibitors for the protection of mild steel in 1 M HCl solution. Also, the efficiency decreased with decreasing inhibitor concentrations. Surface studies ensure the effectiveness of both investigated oils and the reduction of the surface roughness of mild steel. Furthermore, DFT results of the major constituents of Artemisia herba-alba and Juniperus phoenicea EOs revealed insights into the chemical reactivity of the tested oils while supporting the experimental conclusions and showed outstanding adsorption ability of both investigated EOs on the steel surface.

This study aims at the valorization of Taxus baccata (L.) in corrosion inhibition. The effect of the extract on corrosion inhibition of mild steel in 1.0 M HCl solution by weight loss measurements, potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) showed that Taxus baccata (L.) leaves extract is a good corrosion inhibitor with an inhibition efficiency of 98%, 96% and 95% at the concentration of 1.0 g/L respectively. Polarisation curves indicated that the extract acted as a mixed type inhibitor. The adsorption on the mild steel surface obeyed the Langmuir isotherm. The activation energy values ∆G0ads (-29.61 KJ.mol-1) confirmed the physical adsorption process of this inhibitor. The study of adsorption kinetics showed a maximum inhibitory efficiency of 90.5 % after one hour of immersion time. Scanning electron microscopy revealed the formation of a protective layer on the steel surface. Analysis of the extract by gas chromatography revealed the dominance of Diisooctyl phthalate (17.22%), Bicyclo [4.4.0] dec-2-ene-4-ol,2-methyl-9-(prop-1-en-3-ol-2-yl) (16.43%), Methanesulfonic acid,4-oxoadamantan-2-yl ester (8.75%), Diethyl phthalate (8. 31 %), The structural and electronic properties of the main components of this extract were calculated using DFT to better understand the adsorption behaviour and inhibition mechanism of this plant.

This study aims to study the impact of environmental stresses on the chemical compositions of essential oils and the content of secondary metabolites of the plants most used by the rural population: Thymus vulgaris, Mentha pulégium and Rosmarinus officinalis. The results of the study indicate that the percentage of secondary metabolites increased in the second year when temperature and water pressure increased by 50%. Specifically, coumarin increased from 3.94% to 9.23%, saponins increased from 6.17% to 7.78%, tannins increased from 2.90% to 6.12%, alkaloids increased from 6.72% to 15.95%, and flavonoids increased from 7.42% to 12.90%. However, in the fourth year, the temperature continued to increase, and water availability decreased by 75%, leading to a decrease in the rate of secondary metabolites. Coumarin decreased from 9.22% to 6.15%, saponin decreased from 7.80% to 6.79%, tannin decreased from 6.11% to 4.16%, alkaloids decreased from 15.95% to 10.45%, and flavonoids decreased from 12.90% to 9.70%. Similar results were observed for the essential oil yield, which increased in year two from 3.57% to 3.84% and decreased in year four to 1.04%. The same pattern was observed for Mentha pulégium and Rosmarinus officinalis. The gas chromatography analysis of the three essential oil samples showed that the majority of the compounds of the three plants were modified under the conditions of climate change. For Mentha pulégium, pulegone was found to represent the highest proportion in sample two (73.3%), followed by sample one (71.1%), and finally, sample three (61.8%). For Rosmarinus officinalis, the majority of compounds were cineole and camphor, with cineole representing 36% in sample two, 45.89% in sample one, and 43.08% in sample three, and camphor representing 21.44% in sample two, 21.56% in sample three, and 17.44% in sample one. For Thymus vulgaris, the majority of the compounds were Thymol and Carvacrol, which underwent approximately the same modifications as the majority of compounds in the other two plants. The results indicate that environmental stresses can lead to significant changes in these compounds, which can affect the medicinal and aromatic properties of these plants. The findings of this study highlight the need for more research to understand the impacts of climate change on plant species and the potential implications for human health and well-being.