Formation of a pyridinium derivative by reaction of 4-hydroxypentenal with glycine.

4-Hydroxypentenal reacts with glycine in a slightly alkaline (pH 8.8) aqueous solution to 1-(1-carboxymethyl)-3-(2-hydroxypropyl)-pyridinium betaine. The yield of the pyridinium betaine isolated by preparative HPLC was 20 mol% and its structure was ascertained by 13C-NMR, IR, UV and mass spectroscopy. Several other products could be detected by HPLC in the 4-hydroxpentenal-glycine reaction mixture, their instability, however, impeded their preparative isolation. 4-Hydroxyalkenals are toxic products generated during lipid peroxidation and the results described explain in part the mechanism how these aldehydes react with nucleophilic amino groups in tissue.