Effects of hydrodistillation and steam distillation on the chemical composition, antioxidant and antibacterial activities of essential oils from Tagetes minuta L. and Eryngium foetidum L

The extraction method used can significantly influence the chemical composition and biological properties of essential oils (EOs). This study evaluated the effects of hydrodistillation (HD) and steam distillation (SD) on the yield, chemical composition, antioxidant activity, and antibacterial properties of EOs obtained from Tagetes minuta and Eryngium foetidum collected in the Peruvian Amazon. EO composition was characterized by GC–MS, and their antioxidant and antibacterial properties were evaluated via DPPH, radical-scavenging activity and Trolox-equivalent antioxidant capacity from the same DPPH assay, as well as MIC and MBC assays against Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa , and Staphylococcus aureus . The plant species significantly affected the EO yield and refractive index (p < 0.05), whereas the antioxidant and antibacterial responses were influenced by significant species × extraction method interactions (p < 0.01). T. minuta presented a substantially greater EO yield (1.36 ± 0.27%) than did E. foetidum (0.08 ± 0.03%). The hydrodistilled T. minuta EOs presented the highest antioxidant activity, reaching 105.3 ± 10.6 mg of Trolox Eq. mL⁻¹ and 67.0 ± 6.7% DPPH inhibition. GC–MS analysis revealed that E. foetidum oils were dominated by 2-dodecenal (38.99–55.61%), whereas T. minuta oils were characterized by dihydrotagetone (30.67–34.18%), β-ocimene (20.65–23.52%), tagetone (14.97–15.91%), and tagetenone (16.43–28.37%). Hydrodistillation produced a higher relative abundance of 2-dodecenal in E. foetidum and tagetenone in T. minuta . Antibacterial activity depended on both plant species and extraction method. E. foetidum showed stronger in vitro antibacterial activity against the tested bacteria, whereas hydrodistilled T. minuta showed superior antioxidant properties. These findings support further in vitro investigation of the antioxidant and antibacterial properties of these essential oils.