Optimizing pretreatment methods for agarwood (Aquilaria sinensis) essential oil: A comparative analysis of yield, physicochemical properties, and bioactivities

Agarwood essential oil (AEO) is highly valued for its diverse bioactivities, but its development is limited by low extraction yield. In this study, the soaking hydrodistillation (SHD), microwave hydrodistillation (MHD), ultrasonic hydrodistillation (UHD), microwave-ultrasonic hydrodistillation (MUHD), and untreated hydrodistillation (UTHD, control) were evaluated for the extraction of AEO from Aquilaria sinensis ( A. sinensis ). UHD yielded the highest AEO and was further optimized using single-factor experiment and orthogonal design, resulting in optimal parameters of 40 min ultrasound time, 400 W ultrasound power, and 120 h hydrodistillation. The optimized UHD was compared with the traditional SHD in terms of yield, physicochemical, and functional properties of AEO, energy consumption, and environmental impact. Based on GCMS analysis, UHD-AEO yielded a significantly higher sesquiterpenoid content (84.270 ± 0.409 %) than SHD-AEO (81.985 ± 0.675 %). The major compounds identified in UHD-AEO were β-bisabolol, α-costal, kusunol, α-cyperone, agarospirol, 7-epi-γ-eudesmol, and dehydrofukinone. Functionally, UHD-AEO reported a stronger antibacterial effect than SHD-AEO against S. aureus but had limited effects on P. acnes, E. coli , and P. aeruginosa . SHD-AEO showed a greater scavenging effect against DPPH and ABTS free radicals than UHD-AEO with a dose-dependent trend. SHD-AEO exhibited stronger anti-proliferative activity in HepG2, MDA-MB-231, and B16F10 cells, indicating potential for anti-tumor applications. In contrast, UHD-AEO showed lower cytotoxicity, suggesting its potential suitability for pharmaceutical and skincare applications. UHD served as an environmentally friendly and sustainable pretreatment technology for the rapid green extraction of AEO from A. sinensis . • First study linking Aquilaria sinensis essential oil pretreatments to yield, composition, bioactivity, and sustainability. • Ultrasonic hydrodistillation parameters optimized via single-factor and orthogonal designs. • Ultrasonic hydrodistillation yielded essential oil with higher sesquiterpenoid content than soaking hydrodistillation. • Ultrasonic hydrodistillation achieved shorter time, higher yield, stronger antibacterial activity, lower toxicity, and less energy use.