Cysteic acid is the chemical mediator of automotive clearcoat damage promoted by dragonfly eggs

The damage caused by dragonfly eggs on automotive clearcoats exposed to sun light occurs by a chemical mechanism similar to that caused by acid rain. C ysteine and cystine residues present in dragonfly eggs are oxidized during the egg hardening process, which releases hydrogen peroxide, to a cysteic a cid derivative, a strong acid capable to catalyze the hydrolysis of acrylo/ melamine clearcoat polymer. Cysteic acid was indeed identified and quantifi ed by ion-exchange HPLC in dragonfly egg extracts submitted to oxidation by H2O2 followed by acid digestion. Moreover, H2O2 concentration, temperature , and exposure ti:me profiles of cysteic acid formation as well as an appar ent activation energy for cysteine (in dragonfly eggs) oxidation to cysteic acid by H2O2 (32 +/- 2 kJ/mol) were determined. (C) 2001 John Wiley & Sons , Inc.