SEARCH Articles Figures Tables 3,4-Protocatechuate Conversion into protocatechuic acid Protocatechuic Protocatechuic acid Constitution Protocatechuic acid Methyl ether Protocatechuic acid Synthesis Protocatechuic acid effects on PEP Protocatechuic acid esters Protocatechuic acid oxidase Protocatechuic acid oxygenase Protocatechuic acid structure Protocatechuic acid, isolated from Protocatechuic acid, oxidation