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Results for “FOLIC ACID ANTAGONISTS”

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At least 19 recordsLinked to original sources
PubMed1986

Experiments on the biological activities of various fractions of the folic acid antagonist "X-methyl" folic acid.

A crude synthetic preparation called crude "X-methyl" folate has previously been shown to function as a folate antagonist for rats and chicks. This product has been shown to contain two folate antagonists: 9-methyl folate, present as 6% by weight of the product and which has low activity as a folate antagonist for Streptococcus faecalis, and pyrrofolic acid, a compound present in small amounts (0.04%), but having high anti-folate biological activity for S. faecalis. These experiments deal with the antifolate activity of these two fractions for the rat as measured by their effects on histidine oxidation. Rats were fed a purified diet based on 20% vitamin-free casein and containing 1.0% sulfasuxidine. When this diet was supplemented with a marginal amount of folic acid (0.3 mg per kg diet), the addition of 4 g of crude antagonist decreased histidine oxidation and decreased liver folate levels. The addition of 240 mg of pure 9-methyl folic acid (amount of 9-methyl folic acid in 4 g of crude) produced similar decreases in histidine oxidation and liver folate levels. A concentrate of pyrrofolic acid (equivalent to 4 g of crude) free of 9-methyl folic acid produced no decrease in histidine oxidation and minimal changes in liver folate. This indicates that the folate antagonist activity observed previously with animals is probably due to the 9-methyl folic acid component rather than to the pyrrofolic acid activity.

Animals↗
PubMed2001

Neural tube defects in relation to use of folic acid antagonists during pregnancy.

Periconceptional folic acid supplementation reduces the risk of neural tube defects (NTDs). To determine whether periconceptional exposure to folic acid antagonists (FAAs) might therefore increase the risk of NTDs, the authors examined data from an ongoing case-control study of birth defects (1979-1998) in the United States and Canada. They compared data on 1,242 infants with NTDs (spina bifida, anencephaly, and encephalocele) with data from a control group of 6,660 infants with malformations not related to vitamin supplementation. Mothers were interviewed within 6 months of delivery about demographic, reproductive, medical, and behavioral factors and about medication use. The adjusted odds ratios of NTDs related to exposure to FAAs (including carbamazepine, phenobarbital, phenytoin, primidone, sulfasalazine, triamterene, and trimethoprim) during the first or second months after the last menstrual period, compared with no use in either month, were 2.8 (95% confidence interval: 1.7, 4.6) for FAAs as a group, 4.8 (95% confidence interval: 1.5, 16.1) for trimethoprim (based on five exposed cases), and 6.9 (95% confidence interval: 1.9, 25.7) for carbamazepine (six exposed cases). These results are adjusted for region, interview year, periconceptional folic acid supplementation, maternal age, weight, education, and infections early in pregnancy. These findings suggest that a number of FAAs may increase NTD risk, and they provide estimates of risk for selected drugs.

Adult↗
PubMed1977

Mutagenic studies of folic acid antagonists.

Compounds that compete with folic acid (folic acid antagonists [FAAs]) become limited in their usefulness in the treatment of leukemia, malaria, and bacterial infections by the rapid development of resistance. Assays of the plasma levels of certain of these FAAs led to the observation, in about 25% of the determinations, that a higher density of growth of Streptococcus faecium var. durans (ATCC 8043) was obtained at an FAA concentration just below the completely inhibitory level than at one-half this concentration. This and other considerations suggested that FAAs may act not only as selective agents for resistant organisms but also as mutagens. Seven FAAs including amethopterin, pyrimethamine, trimethoprim, chlorguanide triazine, an experimental quinazoline, WR-158,122, and two experimental triazines, WR-99,210 and WR-38,839, were tested for mutagenicity in the Salmonella reversion assay developed by Ames et al. (1975). All were found to be negative for strains TA1535, TA1537, TA1538, TA98, and TA100, both with and without microsomal activation. These compounds were then tested as mutagens for three traits in the folic acid-requiring S. faecium. FAAs were shown to cause mutations to folic acid independence, rifampin resistance, and FAA resistance. It is postulated that the FAAs induce mutations by causing thymine deprivation in the folic acid-requiring host.

Culture Media↗
PubMedDate not supplied

Folic acid antagonists.

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Folic Acid Antagonists↗
PubMed1982

Evaluation of X-methyl folate preparations as possible folic acid antagonists.

Crude X-methyl folate and two purified fractions (purified X-methyl folate and 9-methyl folate) were evaluated as possible folic acid antagonists. Antifolate activity was measured by the deoxyuridine suppression assay, direct measurement of dihydrofolate reductase and morphological changes characteristic of folate deficiency. Cytotoxicity was evaluated by cell growth curves. These drugs were studied in freshly obtained human normal evaluated by cell growth curves. These drugs were studied in freshly obtained human normal bone marrow and leukemia cells as well as in three established cell lines HL-60 (human promyelocytic leukemia), CEM (human T lymphocytes), and L1210 (murine lymphoid leukemia). Purified X-methyl folate and 9-methyl folate at concentrations up to 2X10(-5) M failed to induce cell toxicity or inhibit deoxyuridine suppression of 3H-thymidine into DNA. Dihydrofolate reductase was not inhibited by 9-methyl folate but was partially inhibited by purified X-methyl folate. Crude X-methyl folate (2X10(-1) M) is a weak folate antagonist as compared to methotrexate since it requires a 1,000-fold higher concentration to inhibit cell growth and dihydrofolate reductase activity. In addition, the crude X-methyl folate contains a folate-like fraction since it will correct the abnormal deoxyuridine suppression in folate-depleted cells. None of the drugs tested were able to induce myeloid differentiation in the HL-60 cells. The data suggest that 9-methyl folate would not be active as a folate antagonist antitumor agent and that purified and crude X-methyl folate in large concentrations will inhibit folate metabolism. Additional studies are needed to remove the folate-like activity in the crude material in order to further establish the antitumor effects of the crude X-methyl folate.

Cell Differentiation↗
PubMed2000

Folic acid antagonists during pregnancy and the risk of birth defects.

BACKGROUND: Multivitamin supplementation in pregnant women may reduce the risks of cardiovascular defects, oral clefts, and urinary tract defects in their infants. We evaluated whether the folic acid component of multivitamins is responsible for the reduction in risk by examining the associations between maternal use of folic acid antagonists and these congenital malformations. METHODS: We compared data on exposure to folic acid antagonists that act as dihydrofolate reductase inhibitors and to certain antiepileptic drugs for 3870 infants with cardiovascular defects, 1962 infants with oral clefts, and 1100 infants with urinary tract defects with data for 8387 control infants with malformations the risk of which is not reduced after vitamin supplementation. Mothers were interviewed within six months after delivery about their medication use. RESULTS: The relative risks of cardiovascular defects and oral clefts in infants whose mothers were exposed to dihydrofolate reductase inhibitors during the second or third month after the last menstrual period, as compared with infants whose mothers had no such exposure, were 3.4 (95 percent confidence interval, 1.8 to 6.4) and 2.6 (95 percent confidence interval, 1.1 to 6.1), respectively. The relative risks of cardiovascular defects, oral clefts, and urinary tract defects after maternal exposure to antiepileptic drugs were 2.2 (95 percent confidence interval, 1.4 to 3.5), 2.5 (95 percent confidence interval, 1.5 to 4.2), and 2.5 (95 percent confidence interval, 1.2 to 5.0), respectively. Use of multivitamin supplements containing folic acid diminished the adverse effects of dihydrofolate reductase inhibitors, but not that of antiepileptic drugs. CONCLUSIONS: Folic acid antagonists, which include such common drugs as trimethoprim, triamterene, carbamazepine, phenytoin, phenobarbital, and primidone, may increase the risk not only of neural-tube defects, but also of cardiovascular defects, oral clefts, and urinary tract defects. The folic acid component of multivitamins may reduce the risks of these defects.

Abnormalities, Drug-Induced↗