Reactions of Aqueous Chlorine and Chlorine Dioxide with Tryptophan, N‐Methyltryptophan, and 3‐Indolelactic Acid: Kinetic and Mutagenicity Studies

Abstract

ABSTRACTReactions of tryptophan, N‐methyltryptophan and 3‐indolelactic acid with aqueous chlorine or chlorine dioxide (ClO2) in 0.1M potassium phosphate buffer, pH 6.0, were investigated to determine any structural relationships with regards to kinetics and mutagenicity. The reaction with ClO2 followed pseudo‐first order kinetics, with the half‐life of the respective compounds being 36, 22, and 8 milliseconds. The formation of a dark precipitate in the reaction of tryptophan with HOCl precluded any kinetic comparison. The reaction products of tryptophan with hypochlorous acid (HOCl) or ClO2 were mutagenic to Salmonella typhimurium TA98 and TA100; while those of N‐methyltryptophan with HOCl and ClO2 were more mutagenic toward TA98. Higher recoveries of the reaction products were achieved by passing the acidified (pH 2.5) mixture through an XAD‐8/XAD‐2 resin column.