Carnosine and advanced glycation end products: a systematic review

Advanced glycation end products (AGEs) are a cluster of heterogeneous molecules that are generated in a non-enzymatic reaction by the binding of sugars with amino groups of DNA, lipids and proteins. Carnosine is a naturally occurring dipeptide with antioxidant activity, which inhibits protein carbonylation and glycoxidation. This systematic review searched international sources for all published and unpublished original research in English from any year up to the end of April 2018. An electronic search of PubMed, Scopus and Google Scholar was conducted. 187 articles were initially found and 133 articles were selected after excluding duplicated data. Review articles, studies based on the components of carnosine and studies that were about the effects of carnosine on AGEs-induced changes were excluded. In total, 36 studies met the inclusion criteria. This included 19 in vitro studies, 15 animal studies and two human studies. All but two of the studies indicated that carnosine can prevent the formation of AGEs. The findings of this review indicating that carnosine has anti-glycating properties, and may hinder the formation of protein carbonyls and the cross-links induced by reduced sugars; however, there were few human studies. The mechanism by which carnosine prevents the formation of AGEs needs further investigation.