Metal coordination protocol for the synthesis of-2,3-dehydrosilybin and 19-O-demethyl-2,3-dehydrosilybin from silybin and their antitumor activities

An efficient and practical method to access bioactive 2,3-dehydrosilybin and 19-O-demethyl-2,3-dehydrosilybin using naturally abundant flavonolignan silybin in the presence of metal salt as a chelating agent is described. The procedure presented here has several advantages including one-pot, synthetic ease, and products in high yields with no side reactions, and large-scale feasibility. The dehydrogenation and demethylation proceed smoothly via a one-pot process using the AlCl3/Pyridine system and I2 as the additive. Furthermore, 2,3-dehydrosilybin and 19-O-demethyl-2,3-dehydrosilybin can inhibit the expression of intracellular mature miRNA-21 with IC50 values of 4.46 μM and 8.25 μM, respectively, and show moderate anticancer activities against HeLa cell lines.