Submitted to: Analytical Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2012
Publication Date: 1/9/2013
Citation: Quadri, S., Stratford, R., Boue, S.M., Cole, R.B. 2013. Screening and identification of glyceollins and their metabolites by electrospray ionization tandem mass spectrometry with precursor ion scanning. Analytical Chemistry. 85:1727-1733. Interpretive Summary: A method has been developed for screening soybean glyceollins and their metabolites using mass spectrometry. Under higher-energy collision conditions, employing a triple quadrupole mass spectrometer, a glyceollin breakdown component yields a diagnostic ion at m/z 148. We propose diagnostic ion to be diagnostic of glyceollins and glyceollin metabolites. Using tandem analytical techniques established several metabolites in plasma samples from rats dosed with glyceollins. The primary metabolite was determined to be a sulfated metabolite of glyceollin. Several other metabolites were detected in plasma samples. This method will aid in analysis of glyceollin metabolites in future animal and human studies.
Technical Abstract: A method has been developed for screening glyceollins and their metabolites based upon precursor ion scanning. Under higher-energy collision conditions, employing a triple quadrupole mass spectrometer in the negative ion mode, deprotonated glyceollin precursors yield a diagnostic radical product ion at m/z 148. We propose this resonance-stabilized radical anion, formed in violation of the even-electron rule, to be diagnostic of glyceollins and glyceollin metabolites. Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) established that scanning for precursors of m/z 148 can identify glyceollins and their metabolites from plasma samples originating from rats dosed with glyceollins. Precursor peaks of interest were found at m/z 337, 353, 355, 417, and 433. The peak at m/z 337 corresponds to deprotonated glyceollins, whereas, the others represent metabolites of glyceollins. Accurate mass measurement confirmed m/z 417 to be a sulfated metabolite of glyceollins. The peak at m/z 433 is also sulfated, but it contains an additional oxygen, as confirmed by accurate mass measurement. The latter metabolite differs from the former, likely by the replacement of a hydrogen with a hydroxyl moiety. The peaks at m/z 353 and 355 are proposed to correspond to hydroxylated metabolites of glyceollins, wherein the latter additionally undergoes a double bond reduction.