Formation of Yellow Pigment by the Reaction of 4-Methylthio-3-butenyl Isothiocyanate with L-Ascorbic Acid and Some Dihydroxyphenolic Compounds

Abstract

In order to study the formation of yellow pigment in a radish root extract, a model reaction was conducted. It was found that 4-meth¥ Ithio-3-butenv 1 isothiocyanate (4-MTBI) formed a yellow pigment in an aqueous medium by a reaction with i -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 L-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.