Folates folate

Detection" H4-folate folate folate Folic acid Others Reference... 

Figure 14.2 Chemical structure of folates. Folate molecules consist of pteridine, para-aminobenzoate (pABA), and glutamate moieties. Plants usually contain polyglutamylated forms of folates that are made by the addition of up to about six glutamate residues (which form the y-glutamate tail) attached to the first glutamate, each linked by amide bonds to the preceding molecule of glutamate through the y-carboxyl of the latter. Cl units at various levels of oxidation can be attached to NS and/or N1 0, as indicated by Ri and R2.

Elevated Hey levels can also occur in nutritional deficiencies of vitamin B12 (cobalamin) and folate. Folate or vitamin B12 deficiency can even lead to tHcy levels as high as those seen in the genetic homocystinurias [13]. In addition, a reciprocal relationship between blood levels or intake of these vitamins and tHcy concentrations... 

Individuals affected with hereditary folate malabsorption exhibit early onset of failure to thrive, megaloblastic anemia, and severe mental retardation. Therapy requires the administration of large doses of oral and systemic folates. Folate is reduced and converted to N -methyltetrahydrofolate in intestines and secreted into the circulation. 

Folate Folate receptor Cancer cells/ tumor [45] (Rev. [46])... 

Folates Folates are foUc acid derivatives that are naturally present in foods. FoUc acid is the chemically synthesized form of folate. Folates are involved in many metaboUc pathways such as DNA and RNA biosynthesis, repair and methylation, and amino acid interconversions. These compounds possess antioxidant competence that protects the genome by preventing free radical attack [238]. In humans, folate deficiency is associated with a variety of disorders such as coronary heart disease, osteoporosis, Alzheimer s disease, and increased risk of breast and colorectal cancer [239]. 

Comparison between stable isotope dilution assay (SIDA) and Liquid ehromatography-fluoreseence detection (LC-FD) for food folates. Folate contents are calculated as folic acid in tg/100g. SIDA generally yields higher folate contents as 5-formyl-H4folate was not detectable in LC-FD due to weak fluorescence. 

Folate Folate receptor Reduced folate carrier Proton-coupled folate transporter... 

Folate Folate, a B-complex vitamin, includes the naturally occurring form found in foods as well as the synthetic form (folic acid) found in fortified foods and supplements. The rationale for the recommendation that all women who may become pregnant should take a daily 400 pg folic acid supplement, a preventive measure to reduce the risk of NTDs, has already been discussed. Folate intake is important throughout pregnancy because... 

A search for derivatives of L-glutamate can be performed by a substructure search (SSS) (sec Section 6.3). figure 10,3-24b shows the query of the SSS observe that here, too, the stereochemistry can be specified and this is then considered in the SSS. The query provides 25 hits, including L-glutamatc, N-acctylghjtamate, etc. but also compounds such as tctrahydrofolatc, folate, etc. which would never be found by a name search,... 

Folate Folcysteme Foldan Folded oils Folding-carton inks Folding cartons... 

Purine nucleotides thymidylate methionine serine folates... 

Biochemical Functions. Ascorbic acid has various biochemical functions, involving, for example, coUagen synthesis, immune function, dmg metabohsm, folate metaboHsm, cholesterol cataboHsm, iron metaboHsm, and carnitine biosynthesis. Clear-cut evidence for its biochemical role is available only with respect to coUagen biosynthesis (hydroxylation of prolin and lysine). In addition, ascorbic acid can act as a reducing agent and as an effective antioxidant. Ascorbic acid also interferes with nitrosamine formation by reacting direcdy with nitrites, and consequently may potentially reduce cancer risk. 

L-Tyrosine metabohsm and catecholamine biosynthesis occur largely in the brain, central nervous tissue, and endocrine system, which have large pools of L-ascorbic acid (128). Catecholamine, a neurotransmitter, is the precursor in the formation of dopamine, which is converted to noradrenaline and adrenaline. The precise role of ascorbic acid has not been completely understood. Ascorbic acid has important biochemical functions with various hydroxylase enzymes in steroid, dmg, andhpid metabohsm. The cytochrome P-450 oxidase catalyzes the conversion of cholesterol to bUe acids and the detoxification process of aromatic dmgs and other xenobiotics, eg, carcinogens, poUutants, and pesticides, in the body (129). The effects of L-ascorbic acid on histamine metabohsm related to scurvy and anaphylactic shock have been investigated (130). Another ceUular reaction involving ascorbic acid is the conversion of folate to tetrahydrofolate. Ascorbic acid has many biochemical functions which affect the immune system of the body (131). 

En2ymatic reduction of folic acid leads to the 7,8-dihydrofolic acid (H2 folate) (2), a key substance in biosynthesis. Further reduction, cataly2ed by the en2yme dihydrofohc acid reductase, provides (65)-5,6,7,8-tetrahydrofohc acid (H folate) (3). The folate (3) is the key biological intermediate for the formation of other folates (4—8) (Table 2). 

Radiolabeled folate provides a powerful tool for folate bioavaHabiUty studies in animals and for diagnostic procedures in humans. Deuteration at the 3- and 5-positions of the central benzene ring of foHc acid (31) was accompHshed by catalytic debromination (47,48) or acid-cataly2ed exchange reaction (49). Alternatively, deuterium-labeled fohc acid (32) was prepared by condensing pteroic acid with commercially available labeled glutamic acid (50). 

The metabohcahy active folate cofactors (see Table 2) are prepared synthetically as follows. 7,8-Dihydrofohc acid (2) and 5,6,7,8-tetrahydrofohc acid (3) are prepared via catalytic hydrogenation of fohc acid under controUed reaction conditions (51,52). Optical rotation of (63, R)-H4 folate (3) is [oc] = +14.9° (0.1 NNaOH) and the natural (63)-H folate (3) is [oi] = —16.9° (0.1 NNaOH). 

Methyltetrahydrofohc acid folate) (4) is involved in methionine biosynthesis. Condensation of formaldehyde with folate (3),... 

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