In the paper, two new phosphorylated isoflavones of puerarin were successfully obtained by a modified Atheron-Todd reaction. Further, the interactions of bovine serum albumin (BSA) and puerarin or its phosphorylated products were studied under physiological pH by fluorescence spectroscopy. The results showed that puerarin and its phosphorylated products all could form a non-covalent complex with BSA, while the interactions of the phosphorylated isoflavones with BSA were weaker than puerarin. The quench-ing mechanisms of them with BSA were suggested as a static quenching process, and the binding force was mainly a hydrophobic force. The distances between BSA and puerarin and its phosphorylated isoflavones were less than 7 nm according to the theory of the Förster energy transference. The relationship between the molecule structures of these compounds and the binding ability of them with BSA was preliminarily dis-cussed, and the quenching constants in the presence of various metal ions were also explored.

Key words: fluorescence spectroscopy, puerarin, phosphorylation, bovine serum albumin