Essential oil compositions of Alphonsea philastreana (Pierre) Pierre ex Finet & Gagnep. and Alphonsea gaudichaudiana (Baill.) Finet & Gagnep. from Vietnam.

Essential oils isolated from the air-dried leaves of Alphonsea philastreana and Alphonsea gaudichaudiana growing in Vietnam have been studied for their constituents by means of gas chromatography with flame ionization detector and gas chromatography coupled with mass spectrometry. Sesquiterpenes were the most prominent class of compound identified in the oils. The quantitatively significant constituents of the oils were (E)-β-ocimene (6.9% and 8.5%), bicycloelemene (8.9% and 6.3%), β-caryophyllene (5.1% and 5.9%), α-humulene (5.8% and 4.6%), bicyclogermacrene (9.3% and 6.3%), guaiol (9.0% and 5.2%) and α-eudesmol (8.3% and 5.5%), respectively, for A. philastreana and A. gaudichaudiana. This is the first comprehensive report on the volatile oil constituents of the studied species.