Kinetic evaluation of the reaction between methylglyoxal and certain scavenging compounds and determination of their in vitro dicarbonyl scavenging activity.

This study aimed to investigate the reaction between methylglyoxal and amino acids, polyphenols and sulfur compounds and to provide a new approach for the determination of their dicarbonyl scavenging activities. Various pure compounds and beverages were reacted with methylglyoxal under physiological conditions over a week while monitoring methylglyoxal concentration. From the kinetic data, reaction rate constants and methylglyoxal inhibition ratios (for 2, 6 and 24 h) were calculated for each compound. Time vs methylglyoxal inhibition ratios was plotted for each compound. The area under the curve of this plot for a compound or a beverage was divided to that of cysteine or gallic acid to calculate its equivalent dicarbonyl scavenging activity. The dicarbonyl scavenging activities of some selected compounds were in the following order; phloretin > epicatechin > cysteine > epigallocatechin gallate > gallic acid > creatine > hesperetin > resveratrol > phloridzin > quercetin > chlorogenic acid > naringin > genistein > tryptophan. Based on their dicarbonyl scavenging activities, tested compounds and beverages were classified as "rapid reacting with high capacity", "slow reacting with high capacity", and "slow reacting with low capacity".