A New Essential Oil from the Leaves of the Endemic Andean Species Gynoxys miniphylla Cuatrec. (Asteraceae): Chemical and Enantioselective Analyses.

A previously uninvestigated essential oil (EO) was distilled from Gynoxys miniphylla Cuatrec. (Asteraceae) and submitted to chemical and enantioselective analyses. The qualitative and quantitative analyses were conducted by GC-MS and GC-FID, over two orthogonal columns (5%-phenyl-methylpolysiloxane and polyethylene glycol stationary phases). Major constituents (≥2%) were, on both columns, respectively, as follows: α-phellandrene (16.1-17.2%), α-pinene (14.0-15.0%), germacrene D (13.3-14.8%), trans -myrtanol acetate (8.80%), δ-cadinene (4.2-4.6%), β-phellandrene (3.3-2.8%), ( E )-β-caryophyllene (3.1-2.0%), o -cymene (2.4%), α-cadinol (2.3-2.6%), and α-humulene (1.7-2.0%). All the quantified compounds corresponded to 93.5-97.3% by weight of the whole essential oil, with monoterpenes counting for 53.8-55.6% of the total, and sesquiterpenes for 38.5-41.4%. For what concerns the enantioselective analyses, the chiral components were investigated through a β-cyclodextrin-based enantioselective column (2,3-diethyl-6- tert -butyldimethylsilyl-β-cyclodextrin). A total of six chiral metabolites were analysed and the respective enantiomeric excess calculated as follows: (1 S ,5 S )-(-)-α-pinene (98.2%), (1 S ,5 S )-(-)-β-pinene (11.9%), (1 R ,5 R )-(+)-sabinene (14.0%), ( R )-(-)-α-phellandrene (100.0%), ( R )-(-)-β-phellandrene (100.0%), and ( S )-(-)-germacrene D (95.5%). According to the chemical composition and enantiomeric distribution of major compounds, this EO can be considered promising as a cholinergic, antiviral and, probably, analgesic product.