Ricerc@Sapienza

The electrochemical reduction of caffeine, never carried out previously, yielded in DMF-Et 4 NBF 4 N -formyl- N,1-dimethyl-4-(methylamino)-1 H -imidazole-5-carboxamide, a highly functionalized imidazole product derived from the opening of the uracil ring. This reactivity is different from that of the methylated salt of caffeine, the cathodic reduction of which leads to the opening of the imidazole ring.

Background: Caffeine, theophylline, and theobromine are methylxanthines commonly found in coffee, tea, cola, and cocoa. Other sources may be soft drinks or energy drinks. All of them are stimulants of the nervous system and can be used for the treatment of some diseases. The three xanthines produce addiction with typical abstinence symptoms. Among young people, the consumption of energy beverages is increasing, and the growing market causes concern about the caffeine intake. To evaluate intake of methylxanthines, their accurate determination can be helpful.

A chromatographic procedure (HPLC-DAD) using a relatively rapid gradient has been combined with a chemometric curve deconvolution method, multivariate curve resolution-alternating least squares (MCR-ALS), in order to quantify caffeine and chlorogenic acid in green coffee beans.

Controlled potential electrolyses of caffeine (CAF) were carried out at a Pt electrode in undried acetonitrile (ACN) and ACN-H2O and the products of the anodic oxidation were analyzed by HPLC-PDA-ESI-MS/MS. A higher current efficiency occurred in ACN-H2O, but an analogous chromatographic outline was found in both media, evidencing a reactive pathway of the electrogenerated radical cation CAF•+ with water, added or in trace, as nucleophile. No dimeric forms were evidenced, excluding any coupling reactions.