Carbonylation of skin collagen induced by reaction with methylglyoxal

Our previous studies have shown that glycerin, which is present at high concentrations in moisturizers and skin lotions, gradually oxidizes to produce methylglyoxal (MGO). In this study, we observed that MGO-treated porcine dermis type-I collagen was carbonylated in an MGO concentration- and time-dependent manner. Furthermore, we examined the structure of advanced glycation end products (AGEs) induced by MGO reacting with type-I collagen. Our findings demonstrate that the α chains of collagen reacted with MGO and easily transformed into a modified protein containing a methylglyoxal-derived hydroimidazolone (MG-H1) moiety in a concentration- and time-dependent manner. Moreover, porcine skin proteins underwent carbonylation when the skin section was treated with MGO for four weeks. Analysis of the structure of AGEs on the carbonylated proteins extracted from MGO-treated skin sections revealed that skin collagen had been converted to MG-H1-modified protein. These novel findings suggest that continuous application of MGO to the skin leads to carbonylation of proteins, which may cause prompt accumulation of MG-H1-modified dermis collagen, thereby resulting in morphological and functional changes of collagen in the skin.