Two prenylated retrochalcones from Glycyrrhiza inflata

Two new chalcones, licochalcones C and D, were isolated from the root of Glycyrrhiza inflata (Leguminosae) together with three known chalcones echinatin, licochalcones A and B. Their structures were elucidated as 4,4′-dihydroxy-2-methoxy-3-prenylchalcone and 2-methoxy-3′-prenyl-3,4,4′-trihydroxychalcone, respectively, on a spectroscopic basis. All chalcones obtained from this plant are retrochalcones and lack an oxygen-functionality at the 2′-position. The biogenesis of retrochalcones is briefly discussed in relation to the chemotaxonomy of the genus Glycyrrhiza.