Involvement of Maillard reactions in Alzheimer disease

Maillard reactions have been explored by food chemists for many years. It is only recently that the advanced glycation end products (AGEs), the end products of the Maillard reaction, have been detected in a wide variety of diseases such as diabetes, atherosclerosis, cataractogenesis, Parkinson disease and Alzheimer disease (AD). In this review, we discuss the chemistry and biochemistry of AGE-related crosslinks such as pyrraline, pentosidine, carboxymethyllysine (CML), crosslines, imidazolidinones, and dilysine crosslinks (GOLD and MOLD), as well as their possible involvement in neurodegenerative conditions. Pentosidine and CML are found in elevated amounts in the major lesions of the AD brain. Glycation is also implicated in the formation of the paired helical filaments (PHF), a component of the neurofibrillary tangles (NFTs). Amyloid-beta peptide and proteins of the cerebrospinal fluid are also glycated in patients with AD. In order to ameliorate the effects of AGEs on AD pathology, various inhibitors of AGEs have been increasingly explored. It is hoped that understanding of the mechanism of the AGEs formation and their role in the neurodegeneration will result in novel therapeutics for neuroprotection.