Chemical characterization and correlation analysis of essential oils from four medicinal plants: in vitro and in silico approaches

This work aims to characterize the essential oils (EO) of Salvia rosmarinus, Salvia lavandulifolia, Artemisia herba-alba, and Mentha pulegium by studying their physico-chemical properties, chemical composition, and biological activities. The physicochemical parameters were analyzed to determine and compare the properties of EOs. Biological activities, evaluated by antioxidant and antimicrobial tests, were also explored. A comparative analysis of chemical profiles was also performed to identify the main compounds responsible for the observed biological activities. The results show that 1,8-cineole is the majority compound in S. rosmarinus EO (33.81%), camphene in S. lavandulifolia (26.95%), polegone in M. pulegium (87.48%), and trans-thujone in A. herba-alba (33.91%). Significant antimicrobial activity was observed for all four EOs, with minimum inhibitory concentrations (MICs) ranging from 6.25 to 50 µL/mL. Assessment of antioxidant activity, using three chemical methods, revealed remarkable free radical scavenging and reducing capacities. A. herba-alba EO was the most effective at inhibiting the DPPH free radical (IC₅₀ of 3.015 mg/mL) and reducing iron (EC₅₀ of 1.34 mg/mL), followed by M. pulegium (IC₅₀ 4.01 mg/mL, EC₅₀₌0.677 mg/mL), S. rosmarinus (IC₅₀ 4.51 mg/mL, EC₅₀ = 1.19 mg/mL), and S. lavandulifolia (IC₅₀ 41.35 mg/mL, EC₅₀ = 1.4 mg/mL). The total antioxidant capacity of the four EOs exceeds 140.5 mg of ascorbic acid equivalent per gram of EO. The chemical composition of the EOs supports the biological activity results, indicating that M. pulegium EO is mainly active as an antioxidant and antimicrobial due to the presence of oxygenated ketones. At the same time, S. rosmarinus EO owes its activity to phenols. Principal component analysis revealed significant relationships between EO variables and their biological properties, notably a strong negative correlation between hydrocarbon and oxygenated monoterpenes. In addition, a heat map revealed correlations between chemical composition, antimicrobial capacity and antioxidant activity. Finally, molecular docking studies have modelled the interactions between major compounds and biological targets, confirming the potential of EOs to interact effectively with key enzymes involved in oxidative and antimicrobial processes.