Crystalline Dihydropteroylglutamic Acid

Abstract

THE preparation of dihydropteroylglutamic acid has previously been described by O'Dell et al., who used catalytic hydrogenation of pteroylglutamate¹, and by Futterman, who carried out the reduction with sodium dithionite². The acid prepared by catalytic hydrogenation is unsuitable for many biochemical studies, however, because it contains traces of tetra-hydropteroylglutamic acid³. The material obtained by the method of Futterman is an amorphous discoloured preparation², but was found to be uncontaminated by tetrahydropteroylglutamic acid³. No analytical figures have been given for this material. By reducing purified pteroylglutamate with sodium dithionite according to the method of Futterman and twice precipitating the product by slow adjustment of the pH. between strictly defined values, it has now been found possible to obtain dihydropteroylglutamic acid consistently as a white crystalline product giving analytical results agreeing fairly well with the theoretical values.