Bound fumonisin B1:: Analysis of fumonisin-B1 glyco and amino acid conjugates by liquid chromatography-electrospray ionization-tandem mass spectrometry

To study the formation of fumonisin artifacts and the binding of fumonisins to matrix components (e.g., saccharides and proteins) in thermal-treated food, model experiments were performed. Fumonisin B-1 and hydrolyzed fumonisin B-1 were incubated with alpha-D-glucose and sucrose (mono- and disaccharide models), with methyl CC-D-glucopyranoside (starch model), and with the amino acid derivatives N-alpha-acetyl-L-lysine methyl ester and BOC-L-cysteine methyl ester (protein models). The reaction products formed were analyzed by liquid chromatography-electrospray ionization-tandem mass spectrometry. The incubation Of D-glucose with fumonisin B-1 or hydrolyzed fumonisin B-1 resulted in the formation of Amadori rearrangement products. Whereas conjugates were found following the reaction of sucrose, methyl alpha-D-glucopyranoside, and the amino acid derivatives with fumonisin B-1, the heating with hydrolyzed fumonisin B, yielded no artifacts. For structural determination, the stable reaction product formed by heating of methyl alpha-D-glucopyranoside (as starch model) with fumonisin B-1 was purified and identified by nuclear magnetic resonance spectroscopy as the diester of the fumonisin tricarballylic acid side chains with methyl alpha-D-glucopyranoside. These model experiments demonstrate that fumonisins are able to bind to polysaccharides and proteins via their two tricarballylic acid side chains.