Total Synthesis of Hispidulin and the Structural Basis for Its Inhibition of Proto-oncogene Kinase Pim-1

(Figure Presented). A new method is applied to synthesize hispidulin, a natural flavone with a broad spectrum of biological activities. Hispidulin exhibits inhibitory activity against the oncogenic protein kinase Pim-1. Crystallographic analysis of Pim-1 bound to hispidulin reveals a binding mode distinct from that of quercetin, suggesting that the binding potency of flavonoids is determined by their hydrogen-bonding interactions with the hinge region of the kinase. Overall, this work may facilitate construction of a library of hispidulin-derived compounds for investigating the structure-activity relationship of flavone-based Pim-1 inhibitors.