Abstract
A series of 46 folate and the related compounds including those already evaluated as enzyme inhibitors was tested for their inhibition of bovine milk and mouse liver xanthine oxidase in vitro. We have reconfirmed the inhibitory effect of folic acid on this enzyme N10-Formyl folic acid was even stronger inhibitor than folic acid.Reduced forms of folate and its derivatives, namely N5, N10-methenyltetrahydrofolic acid, tetrahydrofolic acid and dihydrofolic acid were also effective inhibitors of this enzyme, indicating that the biological active forms (e.g. one-carbon transfer) are not necessary for the enzyme inhibitory action. Some pteridine compounds including Neopterin, Lumazine were showed to have comparative effects to folic acid, while p-aminobenzoyl glutamic acid and p-aminobenzoic acid and glutamic acid, and their derivatives studied were without significant activity.
