Abstract
Radix Bupleuri is one of the most widely used herbal medicines in China for the treatment
of fever, pain, and/or chronic inflammation. Quercitrin, epicatechin, and rutin, the
flavonoids present in Radix Bupleuri, have been reported to display anti-inflammatory,
antitumor, and antioxidant biological activities among others. Sulfation has been
reported to play an important role in the metabolism of flavonoids. In this study,
we aimed to systematically identify the human cytosolic sulfotransferase enzymes that
are capable of catalyzing the sulfation of quercitrin, epicatechin, and rutin. Of
the thirteen known human cytosolic sulfotransferases, three (cytosolic sulfotransferase
1A1, cytosolic sulfotransferase 1C2, and cytosolic sulfotransferase 1C4) displayed
sulfating activity toward quercitrin, three (cytosolic sulfotransferase 1A1, cytosolic
sulfotransferase 1A3, and cytosolic sulfotransferase 1C4) displayed sulfating activity
toward epicatechin, and six (cytosolic
sulfotransferase 1A1, cytosolic sulfotransferase 1A2, cytosolic sulfotransferase
1A3, cytosolic sulfotransferase 1B1, cytosolic sulfotransferase 1C4, and cytosolic
sulfotransferase 1E1) displayed sulfating activity toward rutin. The kinetic parameters
of the cytosolic sulfotransferases that showed the strongest sulfating activities
were determined. To investigate the effects of genetic polymorphisms on the sulfation
of quercitrin, epicatechin, and rutin, individual panels of cytosolic sulfotransferase
allozymes previously prepared were analyzed and shown to display differential sulfating
activities toward each of the three flavonoids. Taken together, these results provided
a biochemical basis underlying the metabolism of quercitrin, epicatechin, and rutin
through sulfation in humans.
Key words
Bupleurum scorzonerifolium
- Apiaceae - quercitrin - epicatechin - rutin - sulfation - cytosolic sulfotransferase
- SULT - single nucleotide polymorphism - SNP