Novel yellow compounds, dilysyldipyrrolones a and b, formed from xylose and lysine by the maillard reaction

Abstract

When a solution containing xylose and L-lysine is heated under weakly acidic conditions, it turns brown by the Maillard reaction. We isolated here two novel yellow compounds from a heated solution containing xylose and lysine, and identified pyrrolyl-methylidene- pyrrolone derivatives named dilysyldipyrrolones A and B. Their chemical structures were elucidated by instrumental analyses as 6-[[1-[(S)-5-amino-1-carboxypentyl]- 3-hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-methyl-1,2H- pyrrol-3-one-1-ly]-(S)- 2-amino-hexanoic acid (dilysyldi- pyrrolone A) and 6-[[1-[(S)-5-amino-5- carboxypentyl]- 3-hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-methyl-1,2H- pyrrol-3-one-1-yl]-(S)-2-amino-hexanoic acid (dilysyldi- pyrrolone B). These were the major pigments in the heated solution.