Chemical composition and seasonal variation of the essential oils of leaves of Garcinia gardneriana (Planchon & Triana) Zappi (Clusiaceae)

Abstract

The seasonal factors have influence upon the secondary metabolism of plants in adaptive response to the environmental variation, leading to the biosynthesis of different compounds. Thus, the aim of the present paper was to characterize the chemical composition of the essential oil (EO) from leaves of Garcinia gardneriana (Clusiaceae), in function of the seasonality, in the period throughout the year (from January to December of 2016). The EO was obtained from fresh leaves by hydrodistillation in a modified Clevenger apparatus and analyzed using a gas chromatograph coupled to a mass spectrometer. Thereafter, the chemical constituents of the EO were evaluated by principal component analysis (PCA) and hierarchical cluster analysis (HCA). The EO yield varied differently throughout the year with the highest yield in January (0.38%) and the lowest one in August (0.19%). The EO composition was sesquiterpene hydrocarbons (84.78 - 99.07%) and oxygenated sesquiterpenes (0.45 - 13.80%). The major compounds found were α-cedrene, for the months of January to November, and α-trans-bergamotene for December. PCA and HCA analyses showed that the development stage of the plant may have altered the chemical composition of the EO, since in the flowering period the compounds α-trans-bergamotene and γ-muurolene were higher, which are responsible for attracting pollinators and for the plant’s defense. Moreover, in the fructification period, the production of compounds of the oxygenated sesquiterpenes class, namely (Z)-caryophyllene, spathulenol and caryophyllene oxide increased, what is probably related to the protection of the fruit. Thus, the EO of “bacupari” leaves had high chemical variability, which is likely related to the developmental cycle of the plant