FORMATION OF YELLOW PIGMENT BY THE REACTION OF 4-METHYLTHIO-3-BUTENYL ISOTHIOCYANATE WITH L-ASCORBIC-ACID AND SOME DIHYDROXYPHENOLIC COMPOUNDS

In order to study the formation of yellow pigment in a radish root extract, a model reaction was conducted. It was found that 4-methylthio-3-butenyl isothiocyanate (4-MTBI) formed a yellow pigment in an aqueous medium by a reaction with l-ascorbic acid (l-AsA) and such dihydroxyphenolic compounds as catechol, hydroquinone, dopa, dopamine and caffeic acid. No yellow colored substance was formed when the other ten isothiocyanates were employed instead of 4-MTBI. Also, thiol compounds such as ι -cysteine, dithiothreitol and the reduced form of glutathione had little effect on the formation of the yellow pigment. The possibility that a water-soluble degradation product of 4-MTBI participated in the formation of the yellow pigment is suggested. © 1990 by the Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.