Effects of Hydroxy and Methoxy Substituents on NMR Data in Flavonols

摘要

Kaempferide, kaempferol, and galangin belong to flavonol, one of flavonoid classes. Even they have the same moiety as flavonol, their binding affinities for a hexahistidine-tagged C-terminal nucleotide-binding domain are different with each other. The dissociation constants of flavonol, kaempferide, kaempferol, and galangin are 10.1, 4.5, 6.7, and 5.3 mM, respectively. Galangin contains two more hydroxyl groups than flavonol, and kaempferol has three more hydroxyl groups. Kaempferide differs with kaempferol in only one substituent: 4'-hydroxyl group of kaempferol is switched to 4'-methoxyl group in kaempferide.