Molecular orbital calculations on folic acid and folic acid analogs.
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Folic acid plays an important role in the prevention of neural tube defects (e.g., spina bifida and anencephaly), heart defects, facial clefts, urinary abnormalities, and limb deficiencies. Milk and milk products serve as a potential source for folic acid fortification because of the presence of folate-binding proteins that seem to be involved in folate bioavailability. Although milk is not a good source of folic acid, fortification could help in the prevention of the above-mentioned defects. The objective of this study was to examine the physicochemical characteristics of reduced fat milks fortified with folic acid. Reduced fat milks were prepared using 25, 50, 75, and 100% of the recommended dietary allowance of 400 microg of folic acid. Treatments included addition of folic acid at these levels before and after pasteurization. Color, pH, fat, protein, viscosity, folic acid concentration, folate-binding protein concentration, folate-binding protein profile, standard plate count, and coliform counts were determined on d 1, 7, 14, and 21. A consumer acceptability test was conducted on d 7. Data from the consumer panel were analyzed using ANOVA (PROC GLM) with means separation to determine the differences among treatments. Data obtained from the color, pH, fat, protein, viscosity, folic acid concentration, folate-binding protein concentration, standard plate count, and coliform counts were analyzed using the GLM with a repeated measure in time. Significant differences were determined at P < 0.05 using Tukey's Studentized Range Test. There were no differences in the electrophoretic mobility of folate-binding protein in the samples. The concentration of folic acid was significantly higher in reduced fat milks fortified with folic acid after pasteurization compared with the treatments in which folic acid was added before pasteurization. The consumer panelists did not find any significant differences in flavor, appearance, or texture of folic acid fortified reduced fat milks compared with that of the control. Fortification of reduced fat milks with folic acid can be accomplished without adversely affecting the product characteristics.
Folic acid deficiency represents a vitamin deficiency that may be due either to an inadequacy of the dietary supply or to an increased requirement. It leads to a number of abnormalities including hematological, neurological and cardiovascular disorders. In this study, we investigated whether folic acid deficiency would influence platelet and macrophage activities. For 6 weeks, rats were fed a test diet containing a low amount of folic acid (250 mu g/kg) by comparison with a control diet (750 mu g/kg). We found 40 and 32 percent reductions (P < 0.05) of plasma and erythrocyte folates, respectively in the tested group. Peritoneal macrophages of the folic acid deficient animals exhibited greater (20 x) tissue factor (TF) activity than in the controls. We also found that folate depletion significantly enhanced the thrombin- and ADP-induced platelet aggregation (+64 and + 13 percent, respectively). Moreover, the results of incubations with radiolabeled arachidonic acid indicated that platelets of folic acid deficient animals incorporated more labeling than controls did. When stimulated with thrombin, the mobilization of arachidonate from platelet phospholipids and its subsequent formation of cyclooxygenase and lipoxygenase metabolites were enhanced in the deficient animals. In particular, thromboxane biosynthesis was markedly increased. The analysis of the plasma fatty acid composition showed a decrease in the plasma unsaturation index related to a marked fall of long chain (n-3) fatty acids which was also observed in platelets. These data suggested the occurrence of an oxidative stress in folic acid deficient animals which was confirmed by increases in plasma lipid peroxidation products (more than +20 percent) and an enhanced susceptibility of erythrocytes to free radicals (+23 percent). Altogether these data suggested that folic acid deficiency altered the circulating and cellular fatty acid composition and thus influenced the balance of the platelet eicosanoid synthesis. In addition, total homocysteine and glutathione concentrations were highly increased in plasma from folate-depleted rats. From these results, we conclude that folate deficiency can potentiate the coagulation pathway mediated by the macrophage TF as well as the platelet activation process. It is suggested that these dysfunctions might be related to the loss of (n-3) polyunsaturated fatty acids. The latter could result from an increased lipid peroxidation triggered by the folic acid deficiency-induced hyperhomocysteinemia.
BACKGROUND & AIMS: Patients with metabolic syndrome (MS) have increased cardiovascular risk factors. Dietary modifications mainly polyunsatturated fatty acids intake, can improve them. The present study was performed to assess the effects of enriched milk with omega-3 and oleic fatty acids, folic acid and vitamin E, in these patients. METHODS: We performed a randomized, placebo-controlled and open clinical trial, among 72 patients with MS for 3 months. Thirty-six of them consumed 500 cm(3) per day of semi-skimmed milk (control group), and the others consumed 500 cm(3) per day of enriched milk (test group). Daily supplements in this group were 5.7 g of oleic acid, 0.2g of omega-3 fatty acid, 150 microg of folic acid and 7.5mg of vitamin E. Serum for total and HDL cholesterol, triglycerol, Apo B, glucose, insulin, hs-CRP, homocysteine and fatty acids contents in serum phospholipids, was obtained at the beginning and at the end of the study. LDL cholesterol was calculated by Friedewald formula. RESULTS: Four patients in the test group, and two in the control group dropped out. In the test group a decrease in serum total cholesterol (-6.2%, P=0.006), LDL cholesterol (-7.5%, P=0.032), triglycerol (-13.3%, P=0.016), Apo B (-5.7%, P=0.036), glucose (-5.3%, P=0.013), and homocysteine (-9.5%, P=0.00) was observed. Any of these parameters changed in the control group. CONCLUSIONS: Dietary supplementation with 500 cm(3) of enriched milk with omega-3 fatty acid, oleic acid and folic acid, reduces serum tryglicerides, total and LDL cholesterol, Apo B, glucose and homocysteine in patients with MS. This milk is well tolerated and accepted by the patients.
Folic acid is necessary for cell development; for the metabolism of specific biochemical reactions in the body, such as the conversion of homocysteine to methionine; and for the metabolism of specific anticonvulsant drugs. Folic acid has an interrelationship with vitamin B12. A deficiency of folate increases the risk of NTDs, as well as contributing to hyperhomocystinemia, a condition associated with increased cardiovascular disease and NTDs. For the prevention of NTDs, it is recommended that a woman of childbearing age consume a daily folate intake of 400 micrograms; however, the average dietary folate intake is half that amount, and the FDA folate fortification of cereal grains adds only 100 micrograms daily. The woman in her childbearing years does not meet the recommendation with dietary and food fortification. Periconceptional folic acid supplementation is essential, because the neural tube closes 23 to 27 days after conception. Therefore, a multiple vitamin containing folic acid is the practical solution at present if the food fortification is not increased. The bioavailability of folate in the vitamin preparation is approximately double that of dietary folate. Most preparations contain 400 micrograms of folic acid, and if the woman took a multiple vitamin (400 micrograms of folate) in addition to her diet (230 micrograms of folate), she would not exceed 1000 micrograms (1 mg) daily, which is considered the upper limit of daily folate ingestion by dietary fortification and supplementation before the masking of vitamin B12 becomes a concern. However, in this group of patients, pernicious anemia is rare. Regarding cardiovascular disease in men and women, there are no long-term studies showing the benefit of folic acid in reducing the homocysteine level. At present, there are only estimations. However, they should not be ignored. Although it is not the current standard of practice, adding a multiple vitamin containing folic acid to the regimen of men and women starting anticonvulsant medication should be considered in order to prevent the folate lowering observed with such commonly used drugs as PHT and carbamazepine. Women in childbearing years should be on a folic acid supplement when taking an anticonvulsant drug. In general, it appears that all men and women would benefit from increased folate intake. This can be accomplished through vitamin supplementation when there is compliance. However, if the food fortification for folate is increased in the future, then the issue of vitamin supplementation will have to be readdressed.
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Folic acid supplementation may help prevent the following three common and important disorders: neural tube defect pregnancies, ischemic heart disease and strokes, and possibly colon cancer. Several studies have irrefutably established that folic acid supplementation in proper doses reduces neural tube defect pregnancies. Fortified food would be the most reliable way to address this health issue. Several epidemiologic reports have established a close link between hyperhomocysteinemia and ischemic heart disease. This is supported by evidence obtained from genetic defects leading to elevated plasma levels of homocysteine. There is reasonable evidence to conclude that hyperhomocysteinemia is the actual cause of excessive cardiac diseases. Again, folic acid supplementation in proper doses could potentially reduce ischemic heart disease by 40% There is also some evidence to suggest that folic acid treatment reduces the incidence of colon cancer. The reduction in all three health problems is dependent upon the dose of folic acid administered. The levels needed are rarely supplied by the daily food intake, even under ideal conditions, although breakfast cereals address this problem at least in part. It is proposed that flour be fortified because it is a food product heavily used by most people, and that governmental agencies should oversee such programs because they are responsible for setting public health policies.
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We describe a liquid chromatography (LC) tandem mass spectrometry (MS-MS) method for the determination of 5-methyltetrahydrofolic acid (5-methylTHF) and folic acid concentrations and enrichments in human plasma. It was used to study absorption and initial metabolism in five volunteers with two simultaneously administered oral test doses ([(13)C(6)]folic acid in capsules and [(2)H(2)]folic acid in a drink). [(13)C(5)]5-methylTHF and [(2)H(4)]folic acid were used as internal standards. Plasma samples (2 ml) were purified using folate binding protein affinity columns, followed by a concentration step. After LC separation, folates were detected using positive electrospray ionization MS-MS under multiple reaction monitoring conditions. Calibrations were linear for 5-methylTHF over the range 1.2 x 10(-11) (=limit of detection) to 3.2 x 10(-7)mol/L and for folic acid over the range 5 x 10(-10) (=limit of detection) to 4.5 x 10(-8)mol/L. For 5-methylTHF concentration in plasma, intraassay coefficient of variation was within 8.6% (and for unlabeled 5-methylTHF it was within 2.8%) and interassay coefficient of variation was within 9.0%. For folic acid concentrations these coefficient of variations were within 7.5% and within 6.5%, respectively. The [(13)C(6)] and [(2)H(2)] isotopomers of folic acid and 5-methylTHF were measured in the plasma of each volunteer for 8h. After accounting for the time delay due to capsule opening, the modeling results showed no significant differences in absorption time, first pass effect, and elimination rate in the folic acid test doses in capsule or drink. We conclude that LC-MS-MS offers increased sensitivity for quantification of plasma concentrations and enrichments of 5-methylTHF and folic acid and is applicable to stable-isotope studies in humans.
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Folic acid is an essential nutrient from the B complex group of vitamins. Folate, as a cofactor, is involved in numerous intracellular reactions, and this is reflected in the various derivatives that have been isolated from biological sources. Folic acid is involved in single carbon transfer reactions and serves as a source of single carbon units in different oxidative states. The processes involved in the absorption, transport, and intracellular metabolism of this cofactor are complex. Much of folate is bound tightly to enzymes, indicating that there is not excess of this cofactor and that its cellular availability is protected as well as being strictly regulated. In animals, the liver controls the supply of folate through first pass metabolism, biliary secretion, enterohepatic recirculation, as well as through senescent erythrocyte recycling. Deficiencies of folate can occur for many reasons, including reduced intake, increased metabolism, and/or increased requirements as well as through genetic defects. The effects of folate deficiency include hyperhomocysteinemia, megaloblastic anemia, and mood disorders. Folate deficiency has also been implicated in disorders associated with neural tube defects. Supplementation of grain products such as cereals has been undertaken in several countries as a cost-effective means of reducing the prevelance of neural tube defects. Recently, common polymorphisms have been discovered in several genes associated with folate pathways that may play a role in diseases associated with folate deficiency, particularly mild folate deficiency.
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Induction of apoptosis has been implicated as an anticarcinogenic mechanism of both folic acid and retinoic acid. The ability of retinoic acid or folic acid to induce gastric cancer cell apoptosis was investigated in the human gastric cancer cell lines MKN-45 and MKN-28, and DNA fragmentation was studied in situ by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and DNA agarose gel electrophoresis. The rates of apoptosis in both the poorly differentiated MKN-45 and the well differentiated MKN-28 cell line were less than 5% after treatment with either retinoic or folic acid. Apoptosis may be induced by the administration of retinoic acid or folic acid, and the apoptosis indices of MKN-45 and MKN-28 cells were related to the doses of these drugs. The induction of gastric cancer cell apoptosis may play a role in the anticarcinogenic effect of retinoic acid and folic acid, both of which are potential agents for the treatment of human gastric cancer.
The activity of pyrimethamine and sulfadoxine against two strains of Plasmodium falciparum has been studied in vitro by a radioisotopic technique. Low level antagonism of pyrimethamine resulted from the inclusion of p-aminobenzoic acid, p-aminobenzoylglutamic acid or folic acid in the test medium. Sulfadoxine activity was antagonised slightly by p-aminobenzoic but not by p-aminobenzoylglutamic acid, and antagonised markedly by folic acid at concentrations above 4 X 10(-8) M. At 10(-7) M folic acid, a concentration lower than that of normal RPMI medium 1640, sulfadoxine activity was reduced 7000 to 9000-fold in comparison with controls. These results are of importance in terms of the utilisation of folates by P. falciparum, the susceptibility of the parasite to antifolate drugs and the in vitro determination of parasite susceptibility.
Folic acid in amounts of 2 mumol (0.88 mg) was given by mouth to four patients who had undergone portal vein catheterization. All had normal liver function. The increase in folates in plasma obtained from portal and peripheral veins was followed for three hours with the use of L. casei and S. faecalis as test organisms. The results lend support to the assumption that the liver is the main site of methylation of folic acid when given in physiological amounts.
Folic acid analogues containing an additional nitrogen atom between the phenyl ring and the carbonyl group of the side chain were synthesized. None of the compounds showed significant inhibitory activity against human lymphoblastic leukemia cells (CCRF-CEM) in culture or against Lactobacillus casei (ATCC 7469) growth. Against L1210 leukemia in mice, the aza homologue of folic acid, 4, and the aspartic acid analogue, 14, showed no increase in life span over control animals. These compounds were more toxic in vivo than the corresponding methotrexate analogues. Compound 4 supported the growth of Streptococcus faecium (ATCC 8043), and its tetrahydro derivative supported the growth of Pediococcus cerevisiae (ATCC 8081). These results strongly suggest that 4 can substitute for folate derivatives as cofactors for serine transhydroxymethylase, thymidylate synthetase, and dihydrofolate reductase.