Biological activity of the folacin oxidation products 10-formylfolic acid and 5-methyl-5,6-dihyrofolic acid

Abstract

The biological activity of 10-formylfolic acid (10-formyl-FA) and 5-methyl-5,6-dihydrofolic acid (5methyl-DHF) was examined to determine the potential contribution of these oxidized folates to the folacin activity of foods. Both compounds exhibited high folacin activity for Lactobacillus casei in microbiological assays under standard conditions in the presence of ascorbate. Chick bioassays with plasma folacin as the indicator of biological activity revealed approximately 100% activity for 10formyl-FA and 80% activity for the natural l isomer of 5-methyl-DHF, respectively, relative to folic acid. Tritiated forms of these compounds were synthesized and compared with tritiated folic acid for their incorporation into the liver folacin pools of rats after oral dosing. Fractionation of conjugase-treated liver extracts by HPLC indicated that 10-formyl-FA and 5-methyl-DHF were absorbed and metabolized in a manner that was qualitatively and quantitatively similar to that of tritiated folic acid. These results suggest that the formation of 10-formyl-FA and 5-methyl-DHF in foods by oxidation of reduced folates would not yield important losses of folacin activity.

Intestinal absorption of different types of folate in healthy subjects with an ileostomy

“…90 %) compared with the absorption of folic acid. Each of these folates contributes to overall folate activity (Spies et al 1948;Gregory et al 1984;Baggott et al 1998;Baggott & Johanning, 1999).…”

Determination of Folate Bioavailability with a Rat Bioassay

“…The chick bioassay has been used by Graham et al (13) to examine folate bioavailability in selected fortified foods. Pre vious studies from this laboratory employed chick bioassays to examine the effects of dietary fiber on the bioavailability of folie acid (5) as well as for assessment of folate bioavailability of various foods or the activity of synthetic folates (6,14). An advantage of the chick as an animal model is its apparent lack of susceptibility to variation in its folate status induced by nonfolate components of the diet (5).…”

Modulation of One-Carbon Metabolism by B Vitamins: Implications for Transformation and Progression of Prostate Cancer

“…Pratt (Pratt & Cooper, 1971) and others (Ratanasthien et al, 1974) conjecture that this folate could be formed within the jejunum by bacteria and subject to entero-hepatic circulation and jejunal absorption. Long-term feeding of 10-formylfolic acid produces bioactive folates found to support the growth of chickens (Gregory III et al, 1984) and produces a relatively weak but measurable hematological response in humans with pernicious anemia (Spies & Garcia-Lopez, 1948). Needless to say, more work is needed here.…”