THE PTEROYLGLUTAMATE COMPONENTS OF AMERICAN DIETS AS DETERMINED BY CHROMATOGRAPHIC FRACTIONATION

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Abstract
Mixed American diets composed of ordinary foods were assayed bacteriologically for pterolyglutamate (PGA) activity, both before and after conjugase digestion. Because of the known complexity of such mixtures and the inability of certain organisms to discriminate between related growth factors, 10 dietary extracts were subjected to fractionation on DEAE chromatographic columns. Fractions were identified by chromatographic comparison with reference standards, and by their ability to support growth of Streptococcus faecalis, Lactobacillus casei, and Pediococcus cerevisiae. These diets yielded after conjugase digestion to total of 184 [plus or minus] 67 [mu]g (mean [plus or minus] S. D.) of folic acid acivity daily, according to assays with S. fecalis. On the basis of the microbiological assays of the chromato-graphically separated components it could be calculated that this activity is distributed as follows: N10 formyl PGA-55%, N5formyl PGAH4-34% and 11% in an unsubstituted form, thought to be either PGA or PG2A. Chromatograms assayed using L. casei yielded in some cases additional peaks interpreted as either methyl folates or tri-glutamates. It was concluded that ordinary mixed American diets provide an average of 20 [mu]g daily (range 4 to 69) of folate activity available as unsubstituted pteroylmono- or di-glutanate.

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