Chemometric analysis of the seasonal variation in the essential oil composition of Psidium acutangulum growing in the Brazilian Amazon

Abstract

Psidium acutangulum demonstrated promising results from its extracts for some biological activities, which may favor its use as herbal medicine. However, there is still a lack of research that identifies the chemical components of its essential oil. The present study aimed to evaluate the influence of climatic factors on the yield and the chemical composition of essential oils from the leaves and fruits of P. acutangulum. One specimen was monitored for one year with monthly collections. The essential oils were obtained by hydrodistillation, and the chemical composition was analyzed by gas chromatography coupled to mass spectrometry. Chemometric analyzes were performed to verify climatic influences on yields and the chemical composition of P. acutangulum oils. The average oil yields in the dry season (June–February, 0.7 ± 0.3%) and the rainy season (March–May, 0.9 ± 0.2%) did not show a statistical difference. There was a moderate negative correlation between oil yield and insolation (r = 0.53). The predominant class of EOs for seasonal (S) and fruits (F) were oxygenated sesquiterpenes (S: 27.9–85.0%; F: 15.5%), followed by sesquiterpene hydrocarbons (S: 5.5–46.2%; F: 51.0%) and monoterpene hydrocarbons (S:1.8–16.3%; F: 13.6%). The constituents with the highest content in the EOs of P. acutangulum were caryophyllene oxide (0.0–75.1%, 42.4 ± 18.2%), α-pinene (1.5–12.7%, 6.5 ± 3.7%), and α-cadinol (0.0–11.9%, 5.7 ± 2.2%) in leaves, and for the fruits were E-caryophyllene (21.6%) and α-cadinol (5.1%). Climatic parameters can be correlated with caryophyllene oxide and E-caryophyllene amounts, but not with α-cadinol and α-pinene. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed no separation between the oil samples of P. acutangulum during the dry and rainy periods. However, correlations were observed between the oils’ constituents and the environmental parameters. There is great seasonal variability in P. acutangulum. Prior chemical knowledge must be available before suggesting its use.