New dimers and trimers of the silibinin: synthesis, radical scavenger properties and beyond.

Polyphenols are active compounds of the medicinal plants widely distributed in nature. Despite the few and common biosynthetic origins, polyphenols encompass many subclasses of structurally different entities with a variety of pharmacological properties. Many studies suggest that the mechanisms by which plant polyphenols exert their protective actions against various diseases, are in part due to their redox properties.1Silibinin belongs to flavonolignan class, it is a major component of the Silymarin complex extracted from the milk thistle (Silybum marianum). Silibinin has long been studied for its large variety of pharmacological properties ranging from the antioxidant activity to neuroprotective and antiviral activities. In order to expand the repertoire of the modified Silibinins with high molecular diversity and good water solubility, here, we present a new and efficient method for the synthesis of dimers and trimers of the Silibinin, in which the monomer units are linked by phosphodiester bond Exploiting the selective protection of the Silibinin hydroxyl groups, we carried out a new synthetic approach using the well-established phosphoramidite chemistry. Aiming at the discovery of new pharmacological activities of these molecules, the water solubility, the radical scavenger activity by DPPH test, as well as, their ability to scavenge different reactive oxygen species (1O2 and HO●) have been studied. Additionally, the serum stability and cytoprotective behaviour (X/XO assay on HepG2 cells) of dimers have been evaluated. The combination of both striking antioxidant ability and high water solubility, makes these molecules, promising synthetic metabolites for future therapeutic applications.