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United States Department of Agriculture

Agricultural Research Service

Research Project: Rice as a Source and Delivery System for Nutrients and Lipophilic Bioactive Compounds

Location: Food Processing and Sensory Quality Research

Title: Identification of glyceollin metabolites derived from conjugation with glutathione and glucuronic acid in rats by on-line liquid chromatography-electrospray ionization tandem mass spectrometry

Authors
item Quadri, Syeda -
item BOUE, STEPHEN
item Cole, Richard -
item Stratford, Robert -

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 18, 2014
Publication Date: March 11, 2014
Citation: Quadri, S., Boue, S.M., Cole, R., Stratford, R. 2014. Identification of glyceollin metabolites derived from conjugation with glutathione and glucuronic acid in rats by on-line liquid chromatography-electrospray ionization tandem mass spectrometry. Journal of Agricultural and Food Chemistry. 62(12):2692-2700.

Interpretive Summary: Soy glyceollin metabolites produced in rats following oral glyceollin administration were identified using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Two components were identified as by-products of glutathione conjugation. Mercapturic acid conjugates of glyceollins were also identified. In addition, glucuronidation of glyceollins was observed, giving a peak corresponding to the deprotonated conjugate. This metabolite was confirmed in vitro in rat liver microsomes. Neither glutathione conjugation by-products nor glucuronic acid conjugates of glyceollins have been previously reported.

Technical Abstract: Glyceollin-related metabolites produced in rats following oral glyceollin administration were screened and identified by precursor and product ion scanning using liquid chromatography, coupled on-line with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), to identify all glyceollin metabolites based on production of a diagnostic radical product ion (m/z 148) upon decomposition. Using this approach, precursor peaks of interest were found at m/z 474 and 531. Tandem mass spectra of these two peaks allowed us to characterize them as by-products of glutathione conjugation. The peak at m/z 474 was identified as the deprotonated cysteinyl conjugate of glyceollins with an addition of an oxygen, whereas, m/z 531 was identified as the deprotonated cysteinylglyceine glyceollin conjugate plus an oxygen. These results were confirmed by positive ion (PI) mode analyses. Mercapturic acid conjugates of glyceollins were also identified in NI mode as deprotonated molecules at m/z 500. In addition, glucuronidation of glyceollins was observed, giving a peak at m/z 513 corresponding to the deprotonated conjugate. This metabolite was confirmed in vitro in rat liver microsomes. Neither glutathione conjugation by-products nor glucuronic acid conjugates of glyceollins have been previously reported.

Last Modified: 9/10/2014
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