On the generation of bioactive trigonelline degradation products upon coffee roasting and their bioappearance after coffee consumption

Besides caffeine, the betaine N-methyl nicotinic acid, also known as trigonelline, is commonly reported as the second most abundant alkaloid in raw coffee beans. Upon roasting of coffee beans, trigonelline is partially decomposed to give volatile pyridines as well as non-volatile compounds such as N-methylpyridinium ions, nicotinic acid, and methyl nicotinate. As N-methylpyridinium ions were recently found to exhibit phase I/I I biotransformation enzyme modulating activity in vitro as well as in vivo (SOMOZA et al. 2003), and nicotinic acid, methyl nicotinate, together with nicotinamide, exhibit vitamin B3 activity (Experts Group 2002), there is growing interest in the amounts of these bioactive compounds in roasted coffee, coffee beverages, as well as in their bioappearance after coffee consumption. To meet this demand, straightforward stable isotope dilution analyses (SIDA) were developed for the quantitative determination of trigonelline, nicotinic acid, nicotinamide, methyl nicotinate, as well as N-methylpyridinium ions by means of LC-MS/MS (MRM). Application of the SIDA on coffee samples as well as human urine and plasma samples collected before and after coffee consumption gave first insights into the influence of the roasting degree on the amounts of the individual bioactive compounds in coffee samples as well as their human bioappearance after coffee consumption.