Seasonal variation in yield and chemical composition of Moroccan Thymbra capitata (L.) Cav. essential oil and its corresponding hydrolat extracted essential oil

Abstract

The aim of the present work was to study the variation in yield and chemical composition of the pure essential oil (EO) and essential oil dissolved in its corresponding hydrolat (HEO) of Thymbra capitata (L.) Cav. of Morocco according to its stage of growth. The results obtained revealed that the yield of essential oil increases with the growth of the plant to reach its maximum at post-flowering stage (2.90%). On the other hand, the yield of dissolved essential oil in the corresponding hydrolats peaked at the flowering stage (0.53%) and then dropped. The analysis of these oils was performed by the GC-MS and showed that carvacrol was the major compound of this plant during its growth stage. The highest carvacrol content was noted at the flowering stage for EO (84.26%) and at the pre-flowering stage for HEO (98.54%). However, the evolution of concentration of p-cymene (3.84-6.01%) and g-terpinene (3.45-5.68%) in EO seems to be the opposite of carvacrol. Moreover, these two monoterpene hydrocarbons are absent or almost absent in HEO.