Catalysis of the reaction: 2-oxo-3-enoate-4-benzenoid + H2O = pyruvate + benzaldehyde derivative. Substrates are (3E)-4-(5-amino-2-hydroxy-phenyl)-2-oxo-but-3-ene-1-oic-acid (forms 5-aminosalicylaldehyde) and trans-o-hydroxybenzylidenepyruvate (forms salicylaldehyde).