Relationship between the structure of the flavone-C-glycosides of flax (Linum usitatissimum L.) and their biological activities

Abstract

International audienceAtibiotics are one of the most important discoveries that have saved and is saving millions of lives in the world, but the emergence of resistant bacteria induces little or not effective for these synthetic products. In some situations the appearance of resistance prevents the treatment of infections caused by bacteria. The discovery of alternative antimicrobial agents has become urgently required.Many products of plant origin, in particular the class of flavonoids, exhibit antibacterial activity often associated with a high level of antioxidant power. Despite the many studies on this issue, the relationship between structure and function is currently poorly understood. To fill this gap, the biological activity of 12 flavone C-glycosides structurally close was studied. The structural variability of these compounds (derived from apigenin and luteolin) depends on the position and nature of the sugars, the number of hydroxyl groups and the presence of a methyl group.Thus, orientin, isoorientin, vitexin, isovitexin, swertisin, swertiajaponin, carlinoside, schaftoside, lucenin-1, lucenin-2, vicenin-1 and vicenin-2 were extracted from the aerial part of winter flax (Linum usitatissimum). The hydroalcoholic extract was purified by preparative HPLC and by the drowning-out crystallization method. Then, the control of the purity (greater than 99%) and the confirmation of the chemical structures were carried out by NMR and LC/MS. Antioxidant activity was tested by methods such as DPPH and FRAP and antimicrobial potential was assessed using common foodborne pathogens such as P. aeruginosa, E. coli, L. monocytogenes, L. innocua, S. arizonae, E. faecalis, S. aureus, B. subtilis