Chemical and Enantioselective Analysis of the Leaf Essential Oil from Piper coruscans Kunth (Piperaceae), a Costal and Amazonian Native Species of Ecuador

In the present study, an essential oil was distilled from the leaves of Piper coruscans Kunth, a native Amazonian species belonging to the family Piperaceae and quite common in Ecuador. The chemical analysis was performed by GC-MS (qualitative) and GC-FID (quantitative), on polar and non-polar columns, detecting a total of 58 compounds of which 52 were identified. All the identified compounds were quantified. The essential oil was mainly constituted of sesquiterpenes (54.1&ndash

55.0%) and oxygenated sesquiterpenoids (32.5&ndash

33.6%), the major constituents being: (E)-&beta

caryophyllene (24.1&ndash

25.0%), &alpha

humulene (11.6&ndash

12.0%), caryophyllene oxide (9.3&ndash

10.9%), linalool (4.5&ndash

5.2%), humulene epoxide II (3.6&ndash

4.1%), (E)-nerolidol (3.7&ndash

4.0%), &alpha

copaene (3.7&ndash

3.9%), &alpha

muurolol (3.4&ndash

3.7%), &alpha

selinene (3.4&ndash

3.5%), &beta

selinene (3.1&ndash

3.3%), and one undetermined oxygenated sesquiterpenoid (3.1&ndash

3.3%). The aqueous phase (hydrolate) of the distillation process was also submitted to chemical analysis, showing linalool as the main organic compound in solution, with a concentration of 12.3&ndash

15.7 mg/100 mL. The essential oil was than analyzed for the enantiomeric distribution of its monoterpene constituents, affording the following enantiomeric excesses in two &beta

cyclodextrin-based enantioselective columns: (1S,5S)-(-)-&alpha

pinene (60.0&ndash

69.6%), (1S,5S)-(-)-&beta

pinene (5.2&ndash

7.2%), (R)-(-)-&alpha

phellandrene (72.5&ndash

78.2%), (R)-(+)-limonene (28.6%) and (R)-(-)-linalool (1.8&ndash

3.1%).