Methylglyoxal (MGO) is a reactive α-dicarbonyl produced as an unavoidable byproduct of glycolysis. Because it reacts readily with amino acids, nucleic acids and ethanolamine in phospholipids, MGO is deleterious to living systems and contributes significantly to diabetic complications. The primary defense against MGO is the glyoxalase system that oxidizes MGO to D-lactate. However, about 1% of MGO evades this mechanism and remains free to react with susceptible biomolecules. Consequently MGO, whose concentrations increase chronically in diabetics and temporarily in all individuals after meals, leads to increasing production of Advanced Glycation Endproducts (AGE) in diabetes and aging. Several recent papers suggest that residual MGO, can be trapped by scavengers with the resulting adduct safely removed via the urinary system One such report is Metformin, a drug that not only reduces blood glucose but is also beneficial for cardiovascular health and lowers mortality. In 2016 Kinsky et al. showed that Metformin reacts with MGO in diabetics and the adduct is eliminated in urine. This MGO-scavenging activity is also seen with some endogenous amine-containing compounds such as carnosine, taurine and creatine. In addition to metformin and other amine-based scavengers, there is solid evidence that phytochemicals, such as flavonoids in fruit and vegetables, are also MGO scavengers. Most recently Schalkwjik et al. have published data showing that modest ingestion of quercetin, reduces MGO in plasma by 10%. Prior to that, Sang et al. have shown that three other polyphenols: genistein, 6-shagaol and epicatechin, react with MGO in mice and are subsequently excreted as covalent adducts in urine. These studies can be interpreted in many ways, however the simplest interpretation may be that scavenging of MGO and its elimination may account, in part, for the widely reported positive effects of flavonoids on human health.
B. Szwergold: None. C.B. Miller: None.
