New synthetic method of 8-oxocoptisine starting from natural quaternary coptisine as anti-ulcerative colitis agent.

Quaternary coptisine (1), a natural bioactive quaternary protoberberine alkaloid (QPA), was treated with potassium ferricyanide in aqueous solution of 5 N sodium hydroxide leading to the acquisition of 8-oxocoptisine (2) with much higher yield than reported in the literature. This is the first report of the oxidation of a natural QPA by applying potassium ferricyanide as an oxidant. 8-Oxocoptisine showed significant anti-ulcerative colitis efficacy in vitro with EC50 value being 8.12 × 10− 8 M.