RELEVÂNCIA QUIMIOSSISTEMÁTICA E MONITORAMENTO DA EXPRESSÃO DE γ-LACTONAS EM ESPÉCIES DE LAURACEAE

Abstract

Gamma-lactones are substances composed by a five-membered lactone ring produced by angiosperms of the Magnoliid clade, and despite its potent antiproliferative activity against human tumor cell lines in vitro, its interspecies distribution remains undefined. Among γ- lactones-producing plant species, Lauraceae family can be highlighted: it lacks studies focused on bioprospecting this secondary metabolite class and comprises a challenge to taxonomic and evolutionary studies, once some of its members′ taxonomic delimitation are mainly and, in some cases, poorly supported and understood by morphological and genetic data. Thus, the present work aimed to use metabolomic approaches for the description of Lauraceae intergenus and interspecies relationships based on its specialized metabolites. The chemotaxonomic study was conducted with multivariate treatment (Principal Component Analysis - PCA, and Hierarchical Cluster Analysis - HCA) of data obtained by High Performance Liquid Chromatography coupled to Ultraviolet and High Resolution Mass detectors (HPLC-UV-MS) of 47 samples of Lauraceae plants extracts. In general, such analysis revealed two groups: one composed by species of the Ocotea complex (group 1), and another formed by species of the Mezilaurus clade (group 2). Additional interspecies relationships, previously described by morphological and/or genetic characters, agreed with the performed chemical analysis and, from the data obtained, the γ-lactone rubrenolide, occurring restricted to the section Clinostemon-Mezilaurus-Sextonia, could be proposed as a chemotaxonomic marker for group 2. In situ prospection of γ-lactones was also carried out by analyzing the UPLC-UV-MS profiles of different parts of seedlings cultivated from two species that produce such compounds in mature stage: Aiouea trinervis and Mezilaurus crassiramea. The results obtained pointed out the presence of γ-lactones in seedlings of both species in its first months (4 months after germination), which suggests the importance of this class of bioactive metabolites during the growing stages of these plants.