Short and Efficient Synthesis of Licochalcone B and D Through Acid-Mediated Claisen-Schmidt Condensation

摘要

Licochalcones A-E and echinatin were isolated and characterized from the roots of licorice (Glycyrrhiza inflata). These retrochalcones are an unusual phenolic compound family and are distinguished from ordinary chalcones by the absence of an oxygen functionality at the C-2' and C-6' positions. They have various biological activities including anti-cancer, anti-parasitic, anti-bacterial, superoxide-scavenging and anti-oxidant activities. Among the reported retrochalcones, licochalcone B and D (Fig. 1) strongly inhibited superoxide anion production in the xanthine/ xanthine oxidase system, and displayed potent scavenging activity on 2,2-diphenyl-l-picrylhydrazyl l,l-diphenyl-2-picrylhydrazyl radicals. Licochalcone B and D have also been linked with potent anti-inflammatory activity involving the inhibition of lipopolysaccharide-induced phosphorylation at serine 276 and transcriptional activation of nuclear factor-kappa B. A recent study reported that licochalcone D inhibits mast cell degranulation by inhibiting extracellular Ca~(2+) influx and activation of the MEK-ERK pathway.