Isolation and characterization of (+)-mellein, the first isocoumarin reported in Stevia genus

From the acetone extract obtained of leaves and stems of Stevia lucida Lagasca were isolated the following phenolic derivatives: (+)-mellein (1), hispidulin (2), pectolinaringenin (3) and isosakuranetin (4). These compounds were characterized on the basis of spectroscopic studies, including 1D- and 2D-NMR experiments. The literature review indicated that isocoumarins are rather rare compounds in higher plants. This gives importance to their discovery in the Stevia genus.