Prenylflavonoids from Glycyrrhiza uralensis and their protein tyrosine phosphatase-1B inhibitory activities

Two new 2-arylbenzofurans, glycybenzofuran (1) and cyclolicocoumarone (2), together with 10 known flavonoids including licocoumarone (3), glycyrrhisoflavone (4), glisoflavone (5), cycloglycyrrhisoflavone (6), isoliquiritigenin (7), licoflavone A (8), apigenin (9), isokaempferide (10), glycycoumarin (11), and isoglycycoumarin (12), were isolated from the roots of Glycyrrhiza uralensis and their structures were determined by extensive spectroscopic analyses. Compounds 1 and 5 showed significant protein tyrosine phosphatase-1B (PTP1B) inhibitory activity in vitro with the IC₅₀ values of 25.5 and 27.9 μM, respectively. The structure–activity relationship indicated that the presence of prenyl group and ortho-hydroxy group is important for exhibiting the activity. Kinetic analysis indicated that compound 1 inhibits PTP1B by a competitive mode, whereas compound 5 by a mixed mode.