In a continuing study for discovering urease inhibitors based on flavonoids, nineteen reductive derivatives of flavonoids were synthesized and evaluated against Helicobacter pylori urease. Analysis of structure–activity relationship disclosed that 4-deoxy analogues are more potent than other reductive products. Out of them, 4′, 7, 8-trihydroxyl-2-isoflavene (13) was found to be the most active with IC50 of 0.85 μM, being over 20-fold more potent ...