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European Journal of Obstetrics,... Oct 2020Folate (vitamin B9) is widely accepted to protect against fetal neural tube defects. The main sources of dietary folate are folic acid-fortified foods and folic... (Review)
Review
Folate (vitamin B9) is widely accepted to protect against fetal neural tube defects. The main sources of dietary folate are folic acid-fortified foods and folic acid-containing dietary supplements. However, folic acid is inactive in the human body and must be converted by the liver into the active molecule 5-methyltetrahydrofolate (5-MTHF). 5-MTHF functions as a methyl donor in many metabolic reactions, including the conversion of homocysteine into methionine, the biosynthesis of glycine from serine, and the biosynthesis of DNA precursor molecules. Therefore, folate is fundamental for growth, especially in the embryonic and fetal stages. Prescription of folic acid to women in the preconception period and during pregnancy is a consolidated practice. However, it can pose health risks in certain conditions, such as megaloblastic anemia, where it will conceal megaloblastic anemia due to vitamin B12 deficiency and in cases of reduced hepatic transformation of folic acid (e.g. due to genetic variants or during some pharmacotherapies). Some of these risks can be avoided by supplementation with 5-MTHF rather than folic acid. Because 5-MTHF does not require activation, it is immediately available to mother and fetus and does not accumulate in blood like folic acid does in cases of reduced hepatic transformation. This paper reviews the advantages and disadvantages of folate supplementation with folic acid versus 5-MTHF, with a focus on maternal and fetal health.
Topics: Dietary Supplements; Female; Folic Acid; Humans; Neural Tube Defects; Pregnancy; Tetrahydrofolates
PubMed: 32868164
DOI: 10.1016/j.ejogrb.2020.06.012 -
International Journal of Molecular... Jan 2020Riboflavin (RF) is a water-soluble member of the B-vitamin family. Sufficient dietary and supplemental RF intake appears to have a protective effect on various medical... (Review)
Review
Riboflavin (RF) is a water-soluble member of the B-vitamin family. Sufficient dietary and supplemental RF intake appears to have a protective effect on various medical conditions such as sepsis, ischemia etc., while it also contributes to the reduction in the risk of some forms of cancer in humans. These biological effects of RF have been widely studied for their anti-oxidant, anti-aging, anti-inflammatory, anti-nociceptive and anti-cancer properties. Moreover, the combination of RF and other compounds or drugs can have a wide variety of effects and protective properties, and diminish the toxic effect of drugs in several treatments. Research has been done in order to review the latest findings about the link between RF and different clinical aberrations. Since further studies have been published in this field, it is appropriate to consider a re-evaluation of the importance of RF in terms of its beneficial properties.
Topics: Animals; Dietary Supplements; Drug Interactions; Functional Food; Humans; Riboflavin; Vitamin B Complex
PubMed: 32023913
DOI: 10.3390/ijms21030950 -
Biomedicine & Pharmacotherapy =... Jun 2022Methotrexate (MTX) has been used for the treatment of rheumatoid arthritis (RA) for about forty years and to date MTX remains the part of global standard of treatment... (Review)
Review
Methotrexate (MTX) has been used for the treatment of rheumatoid arthritis (RA) for about forty years and to date MTX remains the part of global standard of treatment for RA. The efficacy of MTX in RA is the result of multiple mechanisms of action. In order to summarize the possible pharmacological mechanisms of MTX in the treatment of RA, this review will elaborate on folate antagonism, promotion of adenosine accumulation, regulation of inflammatory signaling pathways, bone protection and maintenance of immune system function.
Topics: Antirheumatic Agents; Arthritis, Rheumatoid; Humans; Methotrexate
PubMed: 35658215
DOI: 10.1016/j.biopha.2022.113074 -
Current Neuropharmacology 2021Tetrahydrobipterin (BH4) is a pivotal enzymatic cofactor required for the synthesis of serotonin, dopamine and nitric oxide. BH4 is essential for numerous physiological... (Review)
Review
Tetrahydrobipterin (BH4) is a pivotal enzymatic cofactor required for the synthesis of serotonin, dopamine and nitric oxide. BH4 is essential for numerous physiological processes at periphery and central levels, such as vascularization, inflammation, glucose homeostasis, regulation of oxidative stress and neurotransmission. BH4 de novo synthesis involves the sequential activation of three enzymes, the major controlling point being GTP cyclohydrolase I (GCH1). Complementary salvage and recycling pathways ensure that BH4 levels are tightly kept within a physiological range in the body. Even if the way of transport of BH4 and its ability to enter the brain after peripheral administration is still controversial, data showed increased levels in the brain after BH4 treatment. Available evidence shows that GCH1 expression and BH4 synthesis are stimulated by immunological factors, notably pro-inflammatory cytokines. Once produced, BH4 can act as an anti- inflammatory molecule and scavenger of free radicals protecting against oxidative stress. At the same time, BH4 is prone to autoxidation, leading to the release of superoxide radicals contributing to inflammatory processes, and to the production of BH2, an inactive form of BH4, reducing its bioavailability. Alterations in BH4 levels have been documented in many pathological situations, including Alzheimer's disease, Parkinson's disease and depression, in which increased oxidative stress, inflammation and alterations in monoaminergic function are described. This review aims at providing an update of the knowledge about metabolism and the role of BH4 in brain function, from preclinical to clinical studies, addressing some therapeutic implications.
Topics: Biopterins; GTP Cyclohydrolase; Humans; Neuropsychiatry; Nitric Oxide; Serotonin
PubMed: 32744952
DOI: 10.2174/1570159X18666200729103529 -
Journal of Clinical Pharmacy and... Sep 2022High-dose methotrexate (HDMTX) is active against various malignancies; it possesses serious toxicities and is associated with patient characteristics, dosage regimens,... (Review)
Review
High-dose methotrexate (HDMTX) is active against various malignancies; it possesses serious toxicities and is associated with patient characteristics, dosage regimens, comedications, and physiological status. There are many strategies to overcome HDMTX-induced toxicities, such as hydration, alkalization, leucovorin rescue, and haemodialysis. Leucovorin rescue is a cornerstone for toxicity prevention in HDMTX treatment. However, the leucovorin dose adjustment and the existence of leucovorin overrescue are still controversial. At present, various methods for calculating leucovorin doses in different tumour types have been proposed, including empirical calculations based on MTX plasma concentration, the Bleyer nomogram, and other methods. Nonetheless, leucovorin rescue protocols differ greatly across tumour types and medical institutions. Further studies are needed to investigate the optimal dosage regimen for leucovorin rescue in various tumours using HDMTX.
Topics: Drug-Related Side Effects and Adverse Reactions; Humans; Leucovorin; Methotrexate; Neoplasms; Renal Dialysis
PubMed: 35929573
DOI: 10.1111/jcpt.13739 -
ARP Rheumatology Oct 2022Methotrexate (MTX) is an anti-folate drug with anti-proliferative and anti-inflammatory effects. MTX proved to be the most highly effective, fast-acting disease... (Review)
Review
BACKGROUND
Methotrexate (MTX) is an anti-folate drug with anti-proliferative and anti-inflammatory effects. MTX proved to be the most highly effective, fast-acting disease modifying anti-rheumatic drug (DMARD), being widely used for the treatment of rheumatoid arthritis (RA). This review aims to describe the main genetic variants identified concerning proteins that play a role in methotrexate's kinetics and efficiency profile.
METHODS
A literature review was conducted since January of 2000 until December 2020, by searching the PubMed and Embase bibliographic databases, employing the following MeSH terms: methotrexate, pharmacogenetics, pharmacokinetics, and rheumatoid arthritis. The search was limited to articles in English language. Two independent reviewers screened the titles and abstracts followed by a full-text review to assess papers regarding their eligibility. A total of 48 articles matched the research criteria and were analyzed.
RESULTS
Reduced folate carrier 1 (RFC1), a constitutively expressed folate transport protein that has high affinity for MTX is responsible, almost exclusively, for the transport of folate and MTX into the cell. The most studied variant of the gene is the 80G>A variant, mapped within exon 2, on chromosome 21. It seems to improve RA responses to MTX, clinical efficacy with long disease remission. ABC transporters are involved in the efflux of MTX from cells. An increased expression and function of these transporters should decrease MTX concentrations in target cells, resulting in lack of therapeutic response. ABCB1 3435 C/T is a high frequency polymorphism, significantly associated with RA good responses, symptom remission and reduced adverse events, due to MTX treatment. Thymidylate synthase (TYMS) is involved in thymidine synthesis. MTX decreases TYMS activity by inhibition and decreasing the access to tetrahydrofolate (THF) cofactors. The most common genetic variant of the TYMS gene consists of a 28 bp tandem repeat, with double and triple number of repeats (2R and 3R). The 3R allele genotype was associated with decreased efficacy and increased toxicity. The 5,10-methylenetetrahydrofolate reductase (MTHFR) enzyme is indirectly inhibited by MTX. The most common SNPs of the MTHFR gene are C677T and A1298C. Both are associated with a decreased efficacy and an increased toxicity of MTX.
CONCLUSION
MTX response is affected by many gene variants; the effect of each variant separately is likely to be small. Additionally, gene-gene interaction seems to enhance the potential role of linkage disequilibrium. This shows the emerging need for a better gene characterization and to improve the knowledge about variants distribution according to ethnicity, to explain different responses to MTX at an individual level.
Topics: Humans; Methotrexate; Pharmacogenetics; Arthritis, Rheumatoid; Antirheumatic Agents; Polymorphism, Single Nucleotide; Folic Acid
PubMed: 35724450
DOI: No ID Found -
Biomolecules Jan 2022Methylation is an essential biochemical mechanism that is central to the transmission of life, and crucially responsible for regulating gametogenesis and continued... (Review)
Review
Methylation is an essential biochemical mechanism that is central to the transmission of life, and crucially responsible for regulating gametogenesis and continued embryo development. The methylation of DNA and histones drives cell division and regulation of gene expression through epigenesis and imprinting. Brain development and its maturation also depend on correct lipid methylation, and continued neuronal function depends on biogenic amines that require methylation for their synthesis. All methylation processes are carried out via a methyltransferase enzyme and its unique co-factor S-adenosylmethionine (SAM); the transfer of a methyl group to a target molecule results in the release of SAH (SA homocysteine), and then homocysteine (Hcy). Both of these molecules are toxic, inhibiting methylation in a variety of ways, and Hcy recycling to methionine is imperative; this is achieved via the one carbon cycle, supported by the folates cycle. Folate deficiency causes hyperhomocysteinaemia, with several associated diseases; during early pregnancy, deficiency interferes with closure of the neural tube at the fourth week of gestation, and nutraceutical supplementation has been routinely prescribed to prevent neural tube defects, mainly involving B vitamins, Zn and folates. The two metabolic pathways are subject to single nucleotide polymorphisms that alter their activity/capacity, often severely, impairing specific physiological functions including fertility, brain and cardiac function. The impact of three types of nutraceutical supplements, folic acid (FA), folinic acid (FLA) and 5 Methyl THF (MTHF), will be discussed here, with their positive effects alongside potentially hazardous secondary effects. The issue surrounding FA and its association with UMFA (unmetabolized folic acid) syndrome is now a matter of concern, as UMFA is currently found in the umbilical cord of the fetus, and even in infants' blood. We will discuss its putative role in influencing the acquisition of epigenetic marks in the germline, acquired during embryogenesis, as well as the role of FA in the management of cancerous disease.
Topics: Carbon Cycle; Dietary Supplements; Female; Folic Acid; Humans; Infant; Leucovorin; Mutation; Pregnancy; Tetrahydrofolates
PubMed: 35204698
DOI: 10.3390/biom12020197 -
Nutrients Sep 2022The importance of B complex vitamins starts early in the human life cycle and continues across its different stages. At the same time, numerous reports have emphasized... (Review)
Review
The importance of B complex vitamins starts early in the human life cycle and continues across its different stages. At the same time, numerous reports have emphasized the critical role of adequate B complex intake. Most studies examined such issues concerning a specific vitamin B or life stage, with the majority reporting the effect of either excess or deficiency. Deep insight into the orchestration of the eight different B vitamins requirements is reviewed across the human life cycle, beginning from fertility and pregnancy and reaching adulthood and senility, emphasizing interactions among them and underlying action mechanisms. The effect of sex is also reviewed for each vitamin at each life stage to highlight the different daily requirements and/or outcomes. Thiamine, riboflavin, niacin, pyridoxine, and folic acid are crucial for maternal and fetal health. During infancy and childhood, B vitamins are integrated with physical and psychological development that have a pivotal impact on one's overall health in adolescence and adulthood. A higher intake of B vitamins in the elderly is also associated with preventing some aging problems, especially those related to inflammation. All supplementation should be carefully monitored to avoid toxicity and hypervitaminosis. More research should be invested in studying each vitamin individually concerning nutritional disparities in each life stage, with extensive attention paid to cultural differences and lifestyles.
Topics: Adolescent; Adult; Aged; Child; Female; Folic Acid; Humans; Male; Niacin; Pantothenic Acid; Pregnancy; Pyridoxine; Riboflavin; Sex Characteristics; Thiamine; Vitamin B 12; Vitamin B Complex
PubMed: 36235591
DOI: 10.3390/nu14193940 -
Alternative Therapies in Health and... May 2022Folate plays an essential role in the metabolic regulation of amino acids and nucleic acids, and in one-carbon metabolism. Folate must be obtained from the diet, and...
Folate plays an essential role in the metabolic regulation of amino acids and nucleic acids, and in one-carbon metabolism. Folate must be obtained from the diet, and supplementation is strongly recommended in populations at risk for deficiency due to specific conditions. Folic acid is the synthetic form of the vitamin, usually incorporated into foods and supplements. In the body, it must be reduced into the bioactive folate derivative (6S)5-MTHF by cell metabolism. Folate deficiency is related to many health issues such as neurological disorders and can increase cardiovascular disease risk. Women of childbearing age and pregnant women, as well as individuals with MTHFR polymorphism, are the main populations at risk for folate deficiency. Folate supplementation is widely used for fertility, for the inhibition of embryonal neural tube defects (NTDs) in pregnancy and is important for lowering homocysteine levels. (6S)5-MTHF supplementation during pregnancy is preferred over folic acid for its ability to bypass the block in folic acid metabolism linked to enzymatic polymorphism. The use of (6S)5-MTHF can overcome the concerns about the risk for deleterious effects of Unmetabolized Folic Acid (UMFA) related to the use of a supraphysiological dose of folic acid.
Topics: Dietary Supplements; Double-Blind Method; Female; Fertility; Folic Acid; Humans; Pregnancy; Tetrahydrofolates
PubMed: 35653630
DOI: No ID Found -
Methionine synthase is essential for cancer cell proliferation in physiological folate environments.Nature Metabolism Nov 2021Folate metabolism can be an effective target for cancer treatment. However, standard cell culture conditions utilize folic acid, a non-physiological folate source for...
Folate metabolism can be an effective target for cancer treatment. However, standard cell culture conditions utilize folic acid, a non-physiological folate source for most tissues. We find that the enzyme that couples folate and methionine metabolic cycles, methionine synthase, is required for cancer cell proliferation and tumour growth when 5-methyl tetrahydrofolate (THF), the major folate found in circulation, is the extracellular folate source. In such physiological conditions, methionine synthase incorporates 5-methyl THF into the folate cycle to maintain intracellular levels of the folates needed for nucleotide production. 5-methyl THF can sustain intracellular folate metabolism in the absence of folic acid. Therefore, cells exposed to 5-methyl THF are more resistant to methotrexate, an antifolate drug that specifically blocks folic acid incorporation into the folate cycle. Together, these data argue that the environmental folate source has a profound effect on folate metabolism, determining how both folate cycle enzymes and antifolate drugs impact proliferation.
Topics: 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Folic Acid; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Methotrexate; Neoplasms; Tetrahydrofolates
PubMed: 34799701
DOI: 10.1038/s42255-021-00486-5