Methylation of genistein and kaempferol improves their affinities for proteins

Abstract

Methylation of flavonoids appears to be a simple and effective way to improve metabolic resistance and transport of flavonoids. Serum albumins are major soluble proteins serving as transport proteins for many exogenous compounds. This work in here mainly concerns about the effect of methylation of flavonoids on the affinity for human serum albumin (HSA) and ovalbumin. One isoflavone (genistein) and one flavonol (kaempferol) and their monomethylated derivatives at position 4′ (biochanin A and kaempferide) were studied for their affinities for ovalbumin and HSA. The methylation of flavonoids significantly affects the binding process. In general, the methylation of flavonoids improved the affinities for proteins by 2–16 times. This result supports that the methylation of genistein and kaempferol enhanced the transporting ability, which leads to facilitated absorption and greatly increased bioavailability. The methylation increases the hydrophobicity of genistein and kaempferol, and the hydrophobic interaction plays an important role in binding flavonoids to HSA and ovoalbumin.

Keywords::

• methylation
• affinity
• genistein and biochanin A
• kaempferide and kaempferol
• ovalbumin and HSA

Acknowledgement

The authors are grateful for the financial support sponsored by the Nantong University (2010K133 and 2010B61).

Declaration of interest : The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.