Gynoxys reinaldii Cuatrec. and Gynoxys pulchella (Kunth) Cass.: Chemical and Enantioselective Analyses of Two Unprecedented Essential Oils from Ecuador

This study presents the first chemical and enantioselective analyses of essential oils (EOs) derived from the leaves of two endemic species, <i>Gynoxys reinaldii</i> Cuatrec. and <i>Gynoxys pulchella</i> (Kunth) Cass., from Loja, Ecuador. The distillation yields, by weight of dry plant material, were 0.04 ± 0.007% for <i>G. reinaldii</i> and 0.03 ± 0.002% for <i>G. pulchella</i>. For both plants, the chemical analyses were conducted by GC-MS (qualitative) and GC-FID (quantitative), on two stationary phases of different polarity (5% phenyl-methylpolysiloxane and polyethylene glycol). The major components of <i>G. reinaldii</i> EO included germacrene D (22.3-22.1%), α-pinene (14.2-14.1%), and (<i>E</i>)-β-caryophyllene (13.6-14.5%). Similarly, <i>G. pulchella</i> EO was characterized by germacrene D (9.5-12.9%), caryophyllene oxide (7.2-6.7%), and <i>n</i>-tricosane (4.9% in both columns). The enantioselective analyses were carried out with two columns, based on 2,3-diacetyl-6-<i>tert</i>-butyldimethylsilyl-β-cyclodextrin and 2,3-diethyl-6-<i>tert</i>-butyldimethylsilyl-β-cyclodextrin, detecting nine chiral terpenes and terpenoids. In <i>G. reinaldii</i> EO, (1<i>S</i>,5<i>S</i>)-(-)-α-pinene, (1<i>S</i>,5<i>S</i>)-(-)-β-pinene, (1<i>S</i>,5<i>S</i>)-(-)-sabinene, (<i>R</i>)-(-)-α-phellandrene, and (<i>R</i>)-(-)-β-phellandrene were enantiomerically pure, whereas <i>cis</i>-linalool oxide, linalool, terpinene-4-ol, and germacrene D were non-racemic mixtures of enantiomers. In <i>G. pulchella</i>, only (<i>R</i>)-(-)-α-phellandrene was enantiomerically pure. The detection of enantiomerically pure compounds may provide insights into the biosynthetic pathways and potential bioactivities of these EOs.