Essential Oils From Lamiaceae and Myrtaceae Families: Chemical, Antifungal, Antioxidant, and Multivariate Analysis for Multifunctional Purposes

Essential oils (EOs) from three Lamiaceae species (Lavandula dentata, Salvia rosmarinus, and Thymus vulgaris) and seven Eucalyptus species (Myrtaceae) were evaluated for yield, chemical composition, antioxidant capacity, and antifungal activity. Oil yields ranged from 0.18% to 3.6%, with L. dentata producing the highest. Chemical composition was determined using gas chromatography, revealing high levels of oxygenated monoterpenes (39.95%-88.31%). The main constituents were 1,8-cineole, α-pinene, β-pinene, p-cymene, and camphor, except for the EO of T. vulgaris, which was dominated by thymol (72.37%). Antifungal assays showed strong activity for T. vulgaris, moderate activity for others, and the lowest for E. lehmannii. Antioxidant activity was also highest in T. vulgaris, surpassing the Trolox standard. Multivariate statistical analyses, including principal component analysis, hierarchical clustering, Pearson correlation, and partial least squares regression, revealed strong negative correlations (r ≤ -0.87, p < 0.05) and high variable importance (VIP ≥ 2) for thymol, cis-linalool oxide, γ-terpinene, α-terpinene, and 3-carene. These findings support the multifunctional potential of bioactive EOs from Lamiaceae and Myrtaceae as eco-friendly agents for integrated crop protection and antioxidant applications.