Inhibitors of advanced glycation end products from coffee bean roasting by-product

The present study aimed to obtain novel information regarding the pathways of a polyphenol-rich coffee silverskin extract (CSE) for inhibiting the formation of advanced glycation products (AGE). Chlorogenic acid (CGA) is the main phenol present in coffee beans. The contribution of CGA to the antiglycoxidative properties of CSE was also evaluated by analysis of CGA standard. The CGA (90%) and CSE (49%) significantly inhibited (p < 0.001) the formation of fluorescent AGE in a protein–methylglyoxal (MGO) model system (37 °C for 96 h). The lack of MGO-derivative AGE in the presence of CGA and CSE was verified using liquid chromatography–tandem mass spectrometry techniques, which evidenced the almost complete absence of arginine adducts after 24 h of reaction. The inhibitory effect of polyphenols present in CSE may be associated to its carbonyl trapping capacity as well as to its ability to react with side-chains of protein amino residues blocking the reaction sites. In conclusion, aqueous CSE can be considered a natural source of various inhibitors of in vitro formation of AGE acting by different pathways.