Variation in the essential oil composition of calendula officinalis L

Abstract

Variations in the yield and composition of the essential oils from Calendula officinalis L. cultivated in Alice (Eastern Cape) are reported. Essential oils were obtained by hydrodistillation using the Clevenger apparatus and analysis was performed by GC-MS. The yield in essential oil revealed a maximum at the full-flowering stage (0.97%) and a minimum during the pre-flowering stage (0.13%). The composition showed different patterns at different phases of the vegetative cycle. Sesquiterpenes (α-cadinene, α-cadinol, T-muurolol, and epi-bicyclosesquiphellandrene) and monoterpenes (limonene, 1,8- cineole, and trans-β-ocimene) showed highest correlations with the age of the plant. An interesting stage is the post-flowering period, the essential oil being rich in α-cadinene, α- cadinol, T-muurolol, limonene, 1,8-cineole, with p-cymene presenting lower levels. The oils were extracted by hydrodistillation from fresh leaves, dry leaves, and fresh flowers yielding 0.06 %, 0.03 %, and 0.09 %, respectively. The analysis of oils by GCMS revealed a total of 30, 21, and 24 compounds from the fresh leaves, dry leaves, and the flowers, respectively, representing 91.7, 89.8, and 87.5% of the total oil composition. Sesquiterpenoids dominated in the fresh leaves (59.5 %) and flowers (26 %), while the monoterpenes dominated in the dry leaves (70.3 %). T-Muurolol (40.9 %) predominated in the fresh leaf oil, α-thujene (19.2 %) and δ-cadinene (11.8 %) were present in high quantities. In contrast, 1,8-cineole (29.4%), γ-terpenene (11.6 %), δ-cadinene (9.0 %), β- pinene (6.9 %), and α-thujene (6.3 %) were the major components in the dry leaf oil, while in the fresh flower oil, α-thujene (15.9 %), δ-cadinene (13.1 %) and γ-cadinene (10.9 %) were the major components. The significance of the effect of drying and age on essential oil composition is discussed.