Chemical Composition of Essential Oils of Dahlia imperialis (Asteraceae) Growing Wild in Costa Rica

Abstract

Dahlia is a genus of flowering plants of about 35 to 40 species, distributed mainly in Mesoamerica. The aim of this work was to study the chemical composition of the leaflet and capitulum essential oils of D. imperialis growing wild in Costa Rica. The essential oils were obtained by hydrodistillation in a modified Clevenger apparatus. The chemical composition of the oils was performed by capillary gas chromatography with a flame detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) using the retention indices on a DB-5 type capillary column in addition to mass spectral fragmentation patterns. A total of 131 compounds were identified, accounting for 96.5-99.3 % of the total amount of the oils. The major constituents in the leaflet oil were β-pinene (35.2 %), α-phellandrene (21.9 %), α-pinene (18.0 %), p-cymene (8.3 %), limonene (4.3 %) and γ-muurolene (3.9 %). The major constituents in the capitulum (flower head) oil were β-pinene (27.7 %), α-phellandrene (26.2 %), α-pinene (12.4 %), β-phellandrene (6.6 %), limonene (5.6 %), (E)-β-ocimene (2.9 %), and germacrene D (2.2 %). This is the first report about the chemical composition of essential oils from D. imperialis.