Synthesis of a water-soluble analog of 6-methyl-3-N-alkyl catechol labeledwith carbon 13: NMR approach to the reactivity of poison ivy/oak sensitizers toward proteins

A 13-C labeled water soluble derivative of alkylcatechol was synthesized an d reacted with human serum albumin in phosphate buffer at PH 7.4 in air to allow a slow oxidation of the catechol into orthoquinone. The formation of several adducts was evidenced by a combination of C-13 and H-1-C-13 correla tion NMR. Although some adducts could result from a classical o-quinone for mation - Michael type addition, our results suggest that a second pathway, involving a direct reaction of a carbon centered radical with proteins coul d be an important mechanism in the formation of modified proteins, (C) 1999 Elsevier Science Ltd. All rights reserved.