Determination of thiamine modification by polyphenols using K3Fe(CN)6, HgCl2 and CNBr.

The reaction between thiamine (37 micro M) and polyphenols (74 micro M) at 60 degrees, pH 7.4, is without an extremely rapid initial phase. The time-course of reaction is hyperbolic and the log [thiamine] vs time plots pseudo-first order with respect to thiamine. A tentative mechanism is proposed for the reaction after considering results with free radical scavengers and reducing agents together with previous data. As a by-product of the study, CNBr emerges as a better reagent than HgCl2 and K3Fe(CN)6 for thiochrome formation in the presence of polyphenols and reducing agents.