Analysis of Empetrum nigrum L. lipophilic secondary metabolites, their metabolomic profiles and antioxidant activity

ABSTRACT Fourteen hexane-soluble polyphenolic secondary metabolites were previously isolated as individual compounds from Empetrum nigrum L. and identified as three bibenzyls, four 9,10-dihydrophenanthrenes, two chalcones, four dihydrochalcones and one flavanone. In this study, the mass-spectra and retention indexes (RI) of compounds 1-14 without prior derivatization were obtained and the resulting fragmentation pathways rationalized in accordance with literary data and the compounds structures. Preliminary differences in metabolite composition were assessed by comparative profiling using GC-MS chromatography combined with multivariate data analysis for a limited amount of E. nigrum n-hexane extracts obtained from plants growing in three different geographic locations. To characterize antioxidant capacity of isolated compounds 1-14 we used our well-established model based on reactive oxygen species (ROS) production by activated human platelets and showed that most of the examined polyphenols act as antioxidants by inhibition of ROS production.