Comparative Evaluation of Hydrodistillation, Supercritical Fluid Extraction, and Organic Solvent Extraction on Leaf Essential Oils of Chamaecyparis formosensis and C. obtusa var. formosana and Their Potential as Wood-Protective Agents

Abstract

Hydrodistillation (HD), organic solvent extraction (OSE), and supercritical fluid extraction (SFE) were compared in terms of the chemical composition and antifungal activity of leaf essential oils from Chamaecyparis formosensis and C. obtusa var. formosana. Gas chromatography–mass spectrometry revealed notable differences among extraction methods. In C. formosensis, HD-derived oil was dominated by α-pinene (83.4%), SFE-derived oil by kaur-16-ene (51.1%), and OSE-derived oil by phytol (44.4%). In C. obtusa var. formosana, HD oil was rich in sabinene (36.2%) and thujopsene (22.5%), SFE oil in totarol (50.9%), and OSE oil in thujopsene (27.6%) and cedrol (24.8%). Bioassays demonstrated that OSE oil of C. formosensis exhibited the strongest inhibitory effects against Trichoderma sp., Trametes versicolor, Laetiporus sulphureus, and Gloeophyllum trabeum. For C. obtusa var. formosana, HD oil was most effective against Trichoderma sp. and L. sulphureus, whereas SFE oil was most active against G. trabeum. These results highlight the strong influence of the extraction method on both chemical composition and antifungal efficacy of leaf essential oils.