Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. Essential Oils—Chemical and Enantioselective Analyses of Three Unprecedented Volatile Fractions from the Ecuadorian Biodiversity

The present study is the first report on the chemical and enantiomeric compositions of essential oils from the Ecuadorian species <i>Gynoxys hallii</i> Hieron., <i>Gynoxys calyculisolvens</i> Hieron., and <i>Gynoxys azuayensis</i> Cuatrec. All the volatile fractions presented a sesquiterpene-based chemical profile, typical of other volatile fractions from this genus. Both qualitative (GC-MS) and quantitative (GC-FID) chemical analyses were carried out on two stationary phases of different polarity (non-polar and polar). The main constituents of <i>G. hallii</i> essential oil on the two columns, respectively, were α-pinene (33.6-31.5%), (<i>E</i>)-β-caryophyllene (6.2-6.4%), germacrene D (35.7-38.3%), and bicyclogermacrene (3.8-4.0%). In <i>G. calyculisolvens</i>, the major compounds were α-pinene (11.2-11.0%), <i>p</i>-cymene (4.0-3.7%), α-copaene (3.6-3.7%), (<i>E</i>)-β-caryophyllene (8.1-8.3%), germacrene D (20.8-22.0%), and germacrene D-4-ol (8.4-8.6%). Finally, the main components of <i>G. azuayensis</i> were α-pinene (4.5-4.1%), germacrene D (14.1-12.4%), bicyclogermacrene (2.6-3.0%), tridecanal (6.4-6.2%), and spathulenol (7.8-7.1%). Furthermore, enantioselective analyses were conducted on the three volatile fractions, using two stationary phases based on β-cyclodextrins. As a result, twelve chiral components were investigated, detecting both enantiomerically pure compounds and scalemic mixtures with various enantiomeric excess.