10-Formyl-dihydrofolic Acid Is Bioactive in Human Leukemia Cells

Abstract

The bioactivity of 10-formyl-7,8-dihydrofolic acid and 10-formyl-folic acid was determined in human leukemia (CCRF-CEM) cells grown in a folate-depleted medium containing methotrexate. Excess 10-formyl-7,8-dihydrofolic acid, (but not 10-formyl folic acid) supported the growth of these cells, but it was less potent than5-formyl-5,6,7,8-tetrahydrofolic acid (a control). 10-formyl-7, 8-dihydrofolic acid (not 10-formyl folic acid) was active as substrate for aminoimidazole carboxamide ribotide transformylase and dihydrofolate reductase. This is the first experimental evidence that 10-formyl-7,8-dihydrofolic acid is a bioactive folate in mammalian cells. These experiments and several other lines of evidence in the literature suggest that 10-formyl-folic acid must be metabolized to bioactive folate by enteric bacteria before it can be utilized by the vertebrate host.

Comparison of UPLC and HPLC for Analysis of Dietary Folates

“…The purity of all standards was checked according to the procedure of van den Berg et al using molar extinction coefficients reported by Eitenmiller and Landen [8], but for 10-HCO-folic acid the molar extinction coefficient reported by Baggot and Johanning was used [9]. The stock solutions of folates of 200 lg mL -1 (purity corrected) were prepared under subdued light in 0.1 M phosphate buffer pH 6.1 containing 1% sodium ascorbate and 0.1% 2,3-dimercapto-1-propanol.…”

Effect of germination and subsequent oven-drying on folate content in different wheat and rye cultivars

“…Folate standards were stored at À80 C until use. The actual concentration of the folate standard solutions was determined according to van den Berg et al (1994) using the molar extinction coefficients reported by Baggott and Johanning (1999) for 10-HCOefolic acid and by Eitenmiller and Landen (1999) for other folate forms. Standard stock solutions (w200 mg/mL) were prepared according to Jastrebova et al (2003) under subdued light and stored under argon atmosphere at À80 C for a maximum of three months.…”

Folate content in foods commonly consumed in Egypt

“…All were stored at À80°C until use. The actual concentration of folates and folic acid was controlled according to van den Berg, Finglas, and Bates (1994) using the molar extinction coefficients reported by Baggott and Johanning (1999) for 10-HCO-folic acid and molar extinction coefficients reported by Eitenmiller and Landen (1999) for other folate forms. The actual concentrations of standard stock solutions of folates (%200 lg/mL) were prepared according to Jastrebova, Witthöft, Grahn, Svensson, and Jägerstad (2003) under subdued light and stored under argon atmosphere at À80°C for a maximum of three months.…”