Sulfation of dietary flavonoids by human sulfotransferases

Abstract

1. Dietary flavonoids catechin, epicatechin, eriodictyol, and hesperetin were investigated as substrates and inhibitors of human sulfotransferases (hSULTs). Purified recombinant proteins and human intestine cytosol were used as enzyme sources.

2. hSULT1A1 and hSULT1A3 as well as human intestine cytosol can catalyse the sulfation of the investigated flavonoids.

3. Sulfation of catechin, epicatechin, eriodictyol, and hesperetin by recombinant hSULTs showed substrate inhibition at high flavonoid concentrations.

4. Hesperetin and eriodictyol are potent inhibitors of purified hSULT1A1, hSULT1A3, hSULT1E1, and hSULT2A1. Catechin and epicatechin inhibited hSULT1A1 and hSULT1A3, but not hSULT1E1 and hSULT2A1.

5. The sulfation efficacy and potency of inhibition is related to the C-ring structure of flavonoids. These results suggest that dietary flavonoids may regulate human SULT activity and, therefore, affect the regulation of hormones and neurotransmitters, detoxification of drugs, and the bioactivation of pro- carcinogens and pro-mutagens.

Keywords::

• Sulfotransferase
• flavonoids
• sulfation
• inhibition
• kinetics

Acknowledgements

Declaration of interest: This work was supported in part by the NIH (Grant Number GM078606) to G. Chen; the American Cancer Society (Grant Number RSG-07-028-01-CNE to G. Chen; the US Department of Agriculture (USDA) (Grant Number 2006-35200-17137 to G. Chen; and the Oklahoma Center for the Advancement of Science and Technology (OCAST) (Grant Number HR05-015 to G. Chen).