[O-Demethylation of benzoic acids in wheat seedlings]

Various methoxybenzoic acids (anisic, veratric and 3,4,5-trimethoxybenzoic acid) labelled specifically in para and meta methoxyl groups as well as the corresponding 4-hydroxybenzoic acids were added to the nutrient solution of sterile cultures of wheat seedlings.The experiments show that the O-demethylation of benzoic acids is specific for para methoxy groups. meta-O-Methyl carbon atoms appeared only to a very low extent as CO2 and no products formed by demethylation of these groups could be isolated.The products formed by O-demethylation of the para methoxyl groups could be identified as p-hydroxybenzoic acid from anisic acid, vanillic acid from veratric acid and syringic acid from trimethoxybenzoic acid. These 4-hydroxybenzoic acids are normally decarboxylated to a high extent after being fed to plants. When they are formed in the plants by O-demethylation they can be isolated partly as free acids but mainly as their glycosides and glucose esters. These observations and some other indications give evidence of a possible compartmentalisation of plant cells.