Preparative enzymatic synthesis of glucuronides of zearalenone and five of its metabolites.
The resorcylic acid lactones zearalenone ( 1), alpha-zearalenol ( 2), beta-zearalenol ( 3), alpha-zearalanol (zeranol) ( 4), beta-zearalanol (taleranol) ( 5), and zearalanone ( 6) were converted to their glucuronides on a preparative scale in good yields. Reactions were conducted with bovine uridine 5'-diphosphoglucuronyl transferase (UDPGT) as catalyst and uridine 5'-diphosphoglucuronic acid (UDPGA) as cofactor. The glucuronides were isolated by column chromatography and characterized by NMR spectroscopy and mass spectrometry. Although the principal products were 4- O-glucuronides (i.e., linkage through a phenolic hydroxyl), significant quantities of the 6'- O-glucuronides (i.e., linkage through the aliphatic hydroxyl) of alcohols 2, 4, and 5 were also isolated. In the case of 3, the 2- O-glucuronide was isolated as the minor product. Overall isolated yields of glucuronides, performed on a 20-50 mg scale, were typically ca. 80% based on the resorcylic acid lactone starting material. LC-UV-MS (2) analysis of purified specimens revealed MS (2) fragmentations useful for defining the point of attachment of the glucuronide moiety to the zearalenone nucleus.
Stevenson
David E
DE
HortResearch Ltd., Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.
Hansen
Richard P
RP
Loader
Jared I
JI
Jensen
Dwayne J
DJ
Cooney
Janine M
JM
Wilkins
Alistair L
AL
Miles
Christopher O
CO
D000818:Animals; D002417:Cattle; D020719:Glucuronides / Q000096:biosynthesis* / Q000737:chemistry; D014453:Glucuronosyltransferase / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015025:Zearalenone / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism
D020719:Glucuronides; D015025:Zearalenone; D014453:Glucuronosyltransferase