Three new isoflavonoids with antioxidant properties from Ptycholobium contortum (N.E.Br.) Brummitt (Leguminosae)

Abstract Two new pterocarpans, seputhecarpan A ( 1 ) and B ( 2 ) and a new isoflavanone seputheisoflavone ( 3 ) were isolated from the roots of Ptycholobium contortum . Seputhecarpan A and B were identified respectively as 9-hydroxylated and 9,16-dihydroxylated pterocarpans possessing a linear (C-2/C-3) isopropenyldihydrofuran substituent and seputheisoflavone as 5′-α,α-dimethylallyl-4′,5,7-trihydroxy-2′-methoxyisoflavanone. In addition, four known compounds, genistein, isoliquiritigenin, thonningiol and (−)-medicarpin were isolated. Their structures were elucidated using intensive 1D and 2D NMR spectroscopies, CD and MS data. The new compounds were assayed for their antimicrobial, α-glucosidase and antioxidant activities. If the antimicrobial and α-glucosidase inhibitory properties were weak, all the tested compounds exhibited antioxidant activities and seputhecarpan A ( 1 ) was most effective as an antioxidant with an EC50 value of 0.030 mg/ml.