Incubation of fumonisin B(1) and D-glucose in aqueous solutions resulted in the formation of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) in addition to the previously reported N-(carboxymethyl) fumonisin B(1). N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) is the first stable product formed after the Amadori rearrangement of the Schiff base formed by the reaction of the primary amine of fumonisin B(1) and the aldehyde group of D-glucose. N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) was synthesized by reacting fumonisin B(1) with an excess of D-glucose in methanol and heating for 6 h at 64 degrees C. It was purified using C(18) and strong cation exchange solid-phase extraction cartridges and characterized by nuclear magnetic resonance and liquid chromatography-mass spectrometry. Subsequently, N,N-dimethylformamide was found to be a better reaction solvent, requiring reaction for only 2-3 h at 64 degrees C and eliminating the formation of methyl esters. Alkaline hydrolysis of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) gave a mixture of hydrolyzed fumonisin B(1) and hydrolyzed N-(carboxymethyl) fumonisin B(1).