Diurnal variation in the chemical composition of Psidium decussatum DC. (Myrtaceae) essential oil

In this study, the influence of diurnal variation on the chemical composition of the essential oil from the leaves of Psidium decussatum DC., a species of the Myrtaceae family, was investigated. Samples were collected at 5 a.m., 12 p.m., and 6 p.m. The oil extraction method used was steam-assisted hydrodistillation with a Clevenger apparatus. The samples were analyzed by gas chromatography-mass spectrometry (GC-MS). Compound identification was performed by comparing the compounds with the NIST database. Variations in essential oil yield were observed, with higher values in the morning and afternoon and lower values at night. In total, 25 compounds were identified in the 5 a.m. sample and 20 compounds in the 12 p.m. and 6 p.m. samples. The morning sample showed greater chemical diversity. The 6 p.m. sample exhibited higher concentrations of eucalyptol and γ-terpinene. These differences may be associated with variations in light and temperature throughout the day, factors that influence the synthesis of secondary metabolites. It is concluded that the essential oil of P. decussatum varies both qualitatively and quantitatively according to the collection time. It is also concluded that the main constituents were eucalyptol, γ-terpinene, caryophyllene, L-α-terpineol, and linalool, with monoterpenes predominant in all samples. The main contribution of this study is to expand the chemical knowledge of a little-studied species. By providing detailed data on the chemical profile of endemic plants from the semi-arid region of Alagoas, this work supports the sustainable use and technological development of these plants.