Inhibitory effect of 2-arylbenzofurans from Erythrina addisoniae on protein tyrosine phosphatase-1B

Bioassay-guided fractionation of an EtOAc-soluble extract of the stem bark of Erythrina addisoniae (Leguminosae), using an in vitro PTP1B inhibitory assay, resulted in the isolation of three new (1–3) and three known (4–6) 2-arylbenzofuran derivatives. The new compounds were identified as 2-[2′,4′-dihydroxy-3′-(3-methylbut-2-enyl)phenyl]-6-hydroxybenzofuran (1), 2-[2′-methoxy-4′-hydroxy-5′-(3-methylbut-2-enyl)phenyl]-6-hydroxybenzofuran (2), and 2-(2′-methoxy-4′-hydroxyphenyl)-5-(3-methylbut-2-enyl)-6-hydroxybenzofuran (3). The new 2-arylbenzofurans 1–3 inhibited PTP1B activity with IC50 values ranging from 13.6 ± 1.1 to 17.5 ± 1.2 μM in vitro assay. On the basis of the data obtained, 2-arylbenzofurans with prenyl group may be considered as a new class of PTP1B inhibitors.