Natural flavonoids function as chemopreventive agents from Gancao (Glycyrrhiza inflata Batal)

Bioactivity guided assay of Gancao showed the flavonoids as being effective in its extract, which contained 24 flavonoids, including isoflavones (1-4), flavanones (5-7), chalcones (8-17), and flavones (18-24). Components 1, 5, 6, 7, 8, 9, 19, 21, and 22 were for the first time identified in licorice. NQO1 and tumour angiogenesis assay suggested three effective flavonoids, alpha, 4, 2', 4' tetrahydroxydihydrochalcone (8), licochalcone A (12), and licoflavone B (20) as being responsible for the chemopreventive effect. Furthermore, AutoDock 4.2 was employed for molecular docking to clarify the interaction between bioactive flavonoids and NQO1. HPLC analysis was performed to determine the contents of 8, 12 and 20. Therefore the chemical and biological results indicated that flavonoids from the residue of Gancao are promising natural cancer chemopreventive agents. (C) 2015 Elsevier Ltd. All rights reserved.