Seasonal phytochemical changes in Phillyrea angustifolia L.: Metabolomic analysis and phytotoxicity assessment

Plants show seasonality in the secondary metabolite production and the resulting variability can influence plant bioactivity. A study aimed at determining the seasonal metabolic changes in Phillyrea angustifolia and the effects of them on its biological activity has been carried out. The NMR profiles of the extracts obtained from leaves monthly collected from April 2011 to March 2012 revealed a variation of the iridoid content along the year. Oleuropein and the dialdehydic form of decarboxymethyloleuropein ( DHPEA-EDA) were the main metabolites present in the extracts. All the extracts have been tested for their phytotoxicity against Triticum ovatum, a P. angustifolia coexisting plant, using a recently proposed metabolomic based approach. Different plant extracts produced a very diverse response in the target plant metabolome. T. ovatum plants treated with plants collected during summer were very similar to the control, while the extracts obtained from leaves collected in winter, containing the highest amount of oleuropein, were the most active against the test species. The metabolic variation detected in different extracts, could be linked to the phoenological stages or induced by environmental stresses ( drought, temperature, competition, herbivores, etc.) to which plants are exposed in Mediterranean ecosystems. (c) 2013 Phytochemical Society of Europe. Published by Elsevier B. V. All rights reserved.