New C-23 modified of silybin and 2,3-dehydrosilybin: Synthesis and preliminary evaluation of antioxidant properties

Silybin is the major flavonolignan of silymarin and it displays a plethora of biological effects, generally ascribed to its antioxidant properties. Herein we shall describe an efficient synthetic strategy to obtain a variety of new and more water-soluble silybin and 2,3-dehydrosilybin (DHS) derivatives in which the 23-hydroxyl group was converted to a sulfate, phosphodiester, or amine group, using a solution-phase approach. Furthermore a new and efficient method for the preparation of DHS from silybin was developed and optimised. The antioxidant properties of the new compounds were evaluated in a cellular model in vivo and they displayed an antioxidant activity comparable to or higher than silybin and DHS, being able to prevent H 2O 2-induced generation of intracellular reactive oxygen species (ROS). Most of the derivatives also displayed a better hydrophilicity while retaining the biological activities of silybin and they might broaden the in vivo applications of this class of natural compounds.