Inhibition of advanced glycation end-products by chlorogenic and caffeic acids and their detection and quantification by fluorescence and LC-MS

The Maillard reaction produces advanced glycation end-products (AGEs) when reducing sugars glycate with amino acids. These AGEs are formed exogenously and endogenously, and their accumulation in the body over time has been associated with various chronic health conditions. Chlorogenic acid (CGA) and caffeic acid (CA), two hydroxycinnamic acids found in high amounts in products like coffee and apples, have been tested using fluorescence on their ability to inhibit AGE formation. However, many AGEs are non-fluorescent, and these phenolic acids had not been compared using LC-MS. The objective was to compare the inhibitory effects of chlorogenic and caffeic acids on AGEs formed in heated glucose-lysine solutions. Chlorogenic and caffeic acids at 0-1 mM were added to lysine-glucose solutions and were heated to 63°C and 100°C for 30 and 60 mins to determine their impact on AGE formation. Advanced glycation end-products were detected fluorometrically at Ex/Em 370/440 nm, while non-fluorescent AGEs were detected and quantified using LC-MS. This provided a targeted approach to quantifying AGEs using standards to complement previous studies that tested fluorometrically. Solutions heated to 100°C had higher AGE concentrations than those heated to 63°C at the same time points. There was a high negative correlation between AGEs and concentration of phenolic acids. At the same molarities, adding CGA to lysine-glucose solutions resulted in greater inhibition than CA, suggesting that CGA is a more efficient inhibitor at the temperatures and concentrations tested. The combined use of LC-MS and fluorescence provided comprehensive measurements to assess the inhibition of harmful AGE compounds formed through the Maillard reaction. Phenolic acids like CGA and CA can lower formation of unwanted AGEs; therefore, this knowledge can later be further investigated to minimize the presence of AGEs in foods and beverages and ultimately reduce the prevalence of diseases associated with AGE accumulation.