New functions of glucosamine as a scavenger of the lipid peroxidation product malondialdehyde.

Direct reaction between malondialdehyde (MDA) and glucosamine (GlcN) was studied using high-performance liquid chromatography, liquid chromatography/mass spectrometry, spectrophotometry, and spectrofluorometry. The results indicated that GlcN reacted readily with MDA at supraphysiological conditions to form different products, such as a nonfluorescent enamine with an absorption peak at 281 nm (product 1) and a lipofuscin-like fluorescent (Ex. 392 nm/Em. 454 nm) 1,4-dihydropyridine (product 2). GlcN also greatly inhibited the formation of lipofuscin-like fluorescence induced by MDA reacted with bovine serum albumin. The reaction of GlcN with MDA suggested a novel anticarbonylation function of GlcN in pathophysiological situations related to aging-related diseases and provided insight into the reaction mechanism of GlcN in protecting proteins against carbonyl stress.