Chemical Composition and In Vitro Bioactivities of Essential Oil and Volatile Constituents of Hydrosol from Evodia rutaecarpa

Plant-derived essential oils and hydrosols represent valuable sources of volatile compounds with diverse biological properties and potential industrial applications. Nevertheless, comparative information regarding the chemical characteristics and biological activities of essential oil and hydrosol-derived volatile fractions from Evodia rutaecarpa remains limited. Here, essential oil (EO) and volatile constituents recovered from hydrosol (VCH) were comparatively investigated through gas chromatography–mass spectrometry (GC–MS) and evaluated for antibacterial and antifungal activities, cytoprotective effects in RSV-infected Vero cells using a CCK-8 assay, and radical-scavenging activities against DPPH and ABTS radicals. Chemical profiling revealed that EO predominantly contained β-myrcene (21.46 ± 0.31%), D-limonene (18.57 ± 0.51%), and trans-β-ocimene (18.63 ± 0.38%), whereas linalool (14.91 ± 0.63%) and cryptone (11.76 ± 0.69%) were prominent in VCH. For the three bacterial species examined, EO exhibited minimum inhibitory concentrations (MICs) of 1.25–5.00 μL/mL and minimum bactericidal concentrations (MBCs) of 5.00–20.00 μL/mL, compared with 5.00–10.00 μL/mL and 10.00–20.00 μL/mL, respectively, for VCH. Both fractions inhibited the three fungal species at MICs of 0.625–1.25 μL/mL, with minimum fungicidal concentrations (MFCs) of 1.25–2.50 μL/mL for EO and 1.25–5.00 μL/mL for VCH. In RSV-infected Vero cells, VCH exhibited a higher apparent selectivity index (SI) than EO (5.63 versus 2.94) based on the CCK-8 assay. VCH exhibited stronger in vitro radical-scavenging activity than EO in both the DPPH and ABTS assays, with IC50 values of 1.70 and 0.43 mg/mL, respectively, compared with 4.67 and 1.31 mg/mL for EO. Overall, these findings demonstrate marked differences in the chemical composition and biological activities of E. rutaecarpa essential oil and hydrosol-derived volatile constituents, suggesting that E. rutaecarpa, as a natural product with potential applications, warrants further investigation.