Brandisianins A-F, isoflavonoids isolated from Millettia brandisiana in a screening program for death-receptor expression enhancement activity

In a screening study for natural products with tumor-selective apoptosis-inducing properties, six new isoflavonoids (1- 6), named brandisianins A-F, respectively, have been isolated from a MeOH extract of the dried leaves of Millettia brandisiana, together with five known compounds. The structures of the new compounds were elucidated by spectroscopic data interpretation. Among these compounds, brandisianin D (4) exhibited death-receptor 5 expression enhancement activity in a luciferase assay based in DLD-1/ SacI cells. The results suggest that brandisianin D (4) might overcome TRAIL-resistance by an increase in DR5 expression.