Kinetic investigation of the transformations of indol-3-ylcarbinol into oligomeric indolyl compounds based on micellar electrokinetic capillary chromatography

Indol-3-ylcarbinol (I3C) and indol-3-ylmethylcarbonium ion are intermediate products formed in aqueous solutions as a result of indol-3-ylmethylglucosinolate (glucobrassicin) hydrolysis, resulting in various physiologically active compounds. A micellar electrokinetic capillary chromatography (MECC) method has been developed for qualitative and quantitative determination of indolyl oligomers. The method, which is based on cholate as the surfactant, allows efficient separations of di(indol-3-yl)methane (DIM), 2,3-bis(indol-3-ylmethyl)indole (TRI), monomeric, and other oligomeric indolyl products. Theoretical plate numbers per meter of capillary of 1-4 . 4.10(5) have been found. The resolution between I3C and DIM, DIM and TRI, and between TRI and a possible tetramer, were 30, 34 and 5, respectively. Repeatability and linearity of the method have been determined, giving relative standard deviations for the migration times of between 0.3 and 3% and linear correlation coefficients of around 0.99, respectively. The kinetics (reaction orders, rate constants) of I3C transformation into indolyl oligomerisation products, and of the reaction between I3C and a nucleophile (1-propanol), have been studied. The use of the method for separation of the degradation products of a mixture of glucobrassicin and N-methoxyindol-3-ylmethylglucosinolate (neoglucobrassicin) is shown.