Erythrina studies, part 51.: Isoprenylated flavonoids from the stem bark of Erythrina abyssinica

Three new prenylated flavanones, abyssinoflavanones V, VI, and VII (1- 3), together with eight known flavanones (4- 11) and two chalcones (12- 13), were isolated from the stem bark of Erythrina abyssinica. Their structures were elucidated on the basis of spectroscopic and physicochemical analyses. All the isolates, with the exception of 1 and 8, strongly inhibited PTP1B activity in an in Vitro assay with IC50 values ranging from 14.2 +/- 1.7 to 26.7 +/- 1.2 mu M.