<prompt> Uric acid is formed byCatabolism of proteinsCatabolism of ketonesCatabolism of purinesCatabolism of pyrimidines  <response>: Uric acid the end product of purine catabolismis a strong reducing agent. Its role as an antioxidant is paicularly significant in the upper respiratory tract REF : DM VASUDEVAN TEXTBOOK ;8th EDITION ;Page no:547 and 548 