Reaction of 3-dehydroshikimic acid with molecular oxygen and hydrogen peroxide: Products, mechanism, and associated antioxidant activity

Jack E. Richman, Yu Chen Chang, Spiros Kambourakis, K. M. Draths, Erick Almy, Kristi D. Snell, Gale M. Strasburg, J. W. Frost

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

In the presence of molecular oxygen or hydrogen peroxide, inorganic phosphate catalyzes the conversion of 3-dehydroshikimic acid (DHS) into gallic acid. Other products formed in the reaction of DHS with oxygen include protocatechuic acid, tricarballylic acid, and pyrogallol. With hydrogen peroxide as oxidant, pyrogallol formation is not observed, and smaller amounts of tricarballylic acid are produced. Evidence favoring a mechanism involving phosphate-catalyzed tautomerization of DHS to a reactive enediol intermediate follows from the successful isolation of dihydrogallic acid when oxidant is excluded from phosphate-buffered solutions of DHS. The reductone-like solution chemistry of DHS and the radical quenching reactivity of the phenolics formed from DHS prompted an appraisal of DHS antioxidant activity. Based on two different analyses, DHS was discovered to possess significant antioxidant activity relative to α-tocopherol, gallic acid, propyl gallate, and tert-butylhydroquinone.

Original languageEnglish (US)
Pages (from-to)11587-11591
Number of pages5
JournalJournal of the American Chemical Society
Volume118
Issue number46
DOIs
StatePublished - Nov 20 1996

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