Integrated analysis by GC(RI), GC-MS and C-13 NMR of fortunella japonica leaf volatiles obtained by hydrodistillation, microwave- assisted hydrodistillation and hydrolate extraction
Résumé
The chemical composition of the essential oil (EO), microwave extract (ME) and hydrolate extract (HE) from the same batch of leaves of Fortunella japonica, was investigated by combination of chromatographic (GC, CC) and spectroscopic techniques (GC-MS, C-13 NMR). F. japonica essential oil and extracts are complex mixtures of 28-60 compounds being mainly oxygenated sesquiterpenes. The EO composition was dominated by germacrene D (14.9%), beta-elemol (9.1%), cis-guai-6-en-10 beta-ol (6.3%), beta-eudesmol (5.5%), and delta-elemene (5.2%). Limonene was the unique monoterpene identified at appreciable amount (7.1%). The extract obtained by microwave assisted hydrodistillation contained as main components: beta-elemol (12.4%), germacrene D (9.9%), cis-guai-6-en-10 beta-ol (9.0%), beta-eudesmol (8.2%), germacra-1(10),5-dien-4 alpha-ol (7.1%) and alpha-eudesmol (6.4%). Finally, the highest content of oxygenated sesquiterpenes (near 92%) was found in the hydrolate extract displaying cryptomeridiol (23.3%, but totally absent in the EO and ME), beta-eudesmol (20.6%) and alpha-eudesmol (10.7%). Combined analysis by chromatographic and spectroscopic techniques appeared useful for identification of various sesquiterpenols bearing a tertiary alcohol function.