Three new isoflavonoids with antioxidant properties from Ptycholobium contortum (NEBr.) Brummitt (Leguminosae)

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'-alpha,alpha-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, alpha-glucosidase and antioxidant activities. If the antimicrobial and alpha-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. (C) 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.