LABILE CITROVORUM FACTOR IN URINE

Abstract
The bulk of the citrovorum factor activity excreted in human urine by subjects who have ingested folic acid is lost after several hours storage in air at pH 7.0 and 23[degree] C. Upon heating in the presence of ascorbic acid, the labile material is converted into an active stable compound, which possesses the microbiological properties of citrovorum factor. The occurrence of N-10-formyl-folic in urine and the stability properties of "labile" CF suggest that the latter is a reduced derivative of N-10-formyl-folic acid.