Folates natural forms

HPLC does not give a good response to long-chain derivatives of folate, therefore, conversion of the natural form of folate, polyglutamates, to mono- or di-glutamate is required. The enzyme used is y-glutamylcarboxypeptidase, extracted from chicken pancreas, hog kidney, or to a lesser extent from... 

The curative material, which is abundant in green leafy vegetables, was named folic acid. However, this name is usually reserved for the synthetic compound used in dietary supplementation. The natural forms are largely the coenzymes (Fig. 6), which are collectively called folates. The last of the accepted human vitamins to be discovered was vitamin Bn. A cobalt-containing organic compound needed in very small amounts, it cures and prevents pernicious anemia, which was often a fatal disease of people over 60 years of age. Its complex structure (Fig. 7) was determined by X-ray diffraction after numerous efforts at chemicai characterization had failed. However, cy anocobalamin, the compound isolated and the form used in nutritional supplementation, is an artifact of the isolation and synthesis. The natural vitamin may have OH in place of CN but consists largely of the coenzyme forms. 

Milk is not a rich source of dietary folate compared to other foods however, as is the case for riboflavin, folate concentrations can be significantly increased in many dairy products due to microbial fermentation. Among dairy products, fermented milks are considered a good potential matrix for folate fortification because folate-binding proteins present in milk improve folate stability and enhance the bioavailability of both 5-methyltetrahydrofolate (the most predominant natural form of the vitamin) and folic acid (Jones and Nixon 2002 Aryana 2003 Verwei et al. 2003). However, due to the potential risks of fortification with folic acid, the elaboration of fermented milks containing elevated levels of natural folates would be a better suited alternative. 

Folic acid was initially distinguished from vitamin Bi2 as a dietary anti-anemia factor by Wills in the 1930s. The subsequent chemical isolation of folic acid and the identification of its role as a cofactor in one-carbon metabolism led to the elucidation of deficiency diseases at the molecular level. The term folate encompasses the entire group of folate vitamin forms, comprising the naturally occurring... 

Folacin bioavailability varies among the vitamers (120,125). Folic acid is more readily available than the naturally occurring food folates but may be less available from fortified foods than in aqueous solution or tablet form. Food folates have been reported to be 30-80% as available as folic acid. Folacin availability, absorption, and metabolism were recently reviewed (20,120,122). 

Folic Acid (folate). Chemically, folic acid is a pteryl-glutamic acid. The several forms that occur in nature depend on the numbers of glutamic acid units and methyl groups in the molecules. Because of its usual low concentration, folic acid is generally determined in food materials by the microbiological assay with lactobacillus casei and measured turbidimetrically or titrimetrically. Deficiency of this vitamin could result in... 

Its natural occurrence is unique in citrus fruits (4-6J. Furthermore, by employing triple lumen perfusion techniques, it was shown that diphenylhydantoin does not influence the absorption of citrus folate in human volunteers. This may be clinically significant, since diphenylhydantoin in dosages sufficient to control epileptic seizures influences absorption of forms of folate present in other food sources. 

Many of the naturally occurring folates are extremely labile and easily destroyed by cooking. Folic acid itself is stable to heat in an acid medium but is rapidly destroyed under neutral and alkaline conditions. In solution, the vitamin is easily destroyed by light. Folate may occur in a form more active... 

Folate Is a generic term referring to a family of related compounds. All of these compounds represent modifications of the simplest form of the vitamin, folic acid (pteroylglutamic add, PlcGlu). Folic add does not occur in nature in appreciable amounts, though it is readily assimilated by the body and converted to the active cofactor forms of the vitamin. Folic acid is the form of the vitamin used in folate supplements. Folates are modified by reduction and by a poly glutamyl chain or tail. The reduced folates include dlhydrofolate and tetrahydrofolate. 

Fluorouracil (5-FU) is a fluorinated analog of the naturally occurring pyrimidine uracil, originally synthesized in the late 1950s (Table 124—11). It is a prodrug and must be metabolized to the nucleotide form, fluorodeoxyuridine monophosphate (FdUMP), to be active. In the presence of folates, FdUMP binds tightly to and interferes with... 

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