Concise synthesis of licochalcone C and its regioisomer, licochalcone H.

Licochalone C (7a) is a retrochalcone isolated from Glycyrrhiza inflata, which shows potent antioxidant properties and inhibition of bacterial growth and cellular respiration. Biological studies have suggested that licochalcone C attenuates the lipopolysaccharide and interferon-gamma induced inflammatory response by decreasing the expression and activity of inducible nitric oxide synthase and modulating the antioxidant network activity of superoxide dismutase, catalase, and glutathione peroxidase activity. Licochalcone C also inhibits NADH-cytochrome C reductase in the membrane fraction of Micrococcus luteus. Since pharmacological activity studies of licochalcone C are ongoing and the yield of the compound is poor from natural product, we report a concise four step synthesis of licochalcone C (7a) and its regioisomer, tentatively called licochalcone H (7b), by employing acid-mediated Claisen-Schmidt condensation as a key step with 6 and 20 % overall yield, respectively.