试剂 Glu406、Ile 418、Lys417 和 Tyr453 与左美叶酸 (5-MTHF) 相互作用。 Lys 417 和 Tyr 453 在 S1 和 ACE 之间的相互作用中具有重要的生理意义，并且可能作为 ACE2 与 SARS-CoV-2 病毒相互作用的 S1 潜在抑制剂发挥作用 [1]。 Levomefolate (5-MTHF)（50 nM，72 小时）可将人淋巴母细胞系 (LCL) 中的细胞内叶酸代谢活性提高 7 倍，是叶酸的 2 倍。这使其成为有效的叶酸补充剂[2]。

Absorption, Distribution and Excretion
Absorbed in the proximal small intestines via the active proton-coupled folate transporter (PCFT) that transports both oxidized and reduced folic acids. Passive diffusion also occurs at the proximal and distal portions of the small intestines. A single oral dose of 906nmol of levomefolic acid in healthy females resulted in the mean peak plasma concentration of 39.4nmol/L.
Mainly eliminated through renal or fecal excretion. Small proportion of excreted levomefolic acid is in unchanged form as over 99% of tissue folate is in polyglutamate form. Some portions of levomefolic acid is secreted into bile.
Circulates in its free form or loosely bound to plasma proteins

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Metabolism / Metabolites
Levomefolic acid is further converted into tetrahydrofolate (THF) via the vitamin B12-dependent enzyme methionine synthase before effective polyglutamylation by folylpolyglutamate synthetase (FPG). Polyglumate forms of folic acids are more effective substrates for associated enzymes in folate-dependent reactions.

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Biological Half-Life
The mean elimination half-life is approximately 3 hours after 5mg of oral L-methylfolate, administered daily for 7 days.

Protein Binding
Approximately 56% bound to plasma proteins

[1]. Virtual screening and molecular dynamics study of approved drugs as inhibitors of spike protein S1 domain and ACE2 interaction in SARS-CoV-2. J Mol Graph Model. 2020 Dec;101:107716.

[2]. Simultaneous quantification of intracellular concentrations of clinically important metabolites of folate-homocysteine cycle by LC-MS/MS. Anal Biochem. 2020 Sep 15;605:113830.

5-methyltetrahydrofolic acid is a tetrahydrofolic acid that is 5,6,7,8-tetrahydrofolic acid substituted by a methyl group at position 5. It has a role as a human metabolite. It is functionally related to a 5,6,7,8-tetrahydrofolic acid. It is a conjugate acid of a 5-methyltetrahydrofolate(2-).
5-methyltetrahydrofolic acid is a methylated derivate of tetrahydrofolate. It is generated by methylenetetrahydrofolate reductase from 5,10-methylenetetrahydrofolate and used to recycle homocysteine back to methionine by 5-methyltetrahydrofolate-homocysteine methyltransferases (also called methionine synthases).
Levomefolic acid (INN) is the metabolite of folic acid (Vitamin B9) and it is a predominant active form of folate found in foods and in the blood circulation, accounting for 98% of folates in human plasma. It is transported across the membranes including the blood-brain barrier into various tissues where it plays an essential role in the DNA synthesis, cysteine cycle and regulation of homocysteine, where it methylates homocysteine and forms methionine and tetrahydrofolate (THF). Levomefolate is approved as a food additive and is designated a GRAS (generally regarded as safe) compound. It is available commercially as a crystalline form of the calcium salt (Metafolin(R)), which has the stability required for use as a supplement. Supplementation of levomefolic acid is desired over folic acid due to reduced potential for masking vitamin B12 deficiency symptoms.
5-Methyltetrahydrofolic acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655).
Levomefolic acid is a Folate Analog.
Levomefolic acid has been reported in Homo sapiens with data available.
L-methylfolate is a nutritional supplement containing the biologically active form of the B9 vitamin folate, 5-methyltetrahydrofolate (L-methylfolate), with potential antineoplastic activity. Upon administration, L-methylfolate is able to provide methyl groups allowing an increase in the level of DNA methylation in the promoter regions of certain tumor-promoting genes, thereby reversing the DNA hypomethylation of these genes and inactivating them. This may result in a decrease of both tumor cell proliferation and tumor progression. In addition, administration of L-methylfolate may sensitize tumor cells to the cytotoxic effects of other chemotherapeutic agents. Unlike folic acid, L-methylfolate is able to cross the blood brain barrier and could be beneficial in the treatment of brain tumors. DNA hypomethylation of certain genes leads to chromosome instability and contributes to tumor development.
See also: 5-Methyltetrahydrofolic acid (annotation moved to).

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Drug Indication
For the treatment and prevention of folate deficiency and for use as an antidote against folic acid antagonists. Contained in oral contraceptives to reduce the risk of neural tube defects arising from folic acid deficiency for pregnant women who conceived during use or shortly after the discontinuation of the product. Being studied for use as a treatment for cardiovascular diseases and adjunct therapy for patients undergoing antidepressant pharmacotherapy.

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Mechanism of Action
Levomefolic acid plays a critical role in methylating homocysteines into methionine by acting as a methyl donor in a reaction catalyzed by vitamine B12-dependent methionine synthase. Homocysteine must either be further metabolized via transulfuration to become cysteine, taurine, and glutathione via a B6-dependent process, or re-methylated to become methionine again. Methionine formed from remethylation of homocysteine by levomefolic acid forms the downstream metabolite S-adenosylmethionine (SAMe), which is involved in numerous biochemical methyl donation reactions, including reactions forming monoamine neurotransmitters. Studies suggest that high plasma levels of homocysteine is associated with increased incidences of arterial plaque formation.

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Pharmacodynamics
Levomefolic acid is an active metabolite of folic acid and a methyl group donor in one-carbon metabolism reactions. It regulates important cellular functions such as DNA biosynthesis, gene expression regulation, amino acid synthesis and metabolism, and myelin synthesis and repair. As a only form of folate that can cross the blood-brain barrier, it acts as a cofactor in the production of monoamine neurotransmitters such as dopamine, serotonin and norepinephrine. Levomefolic acid is also involved in red blood cell formation.

C20H25N7O6

459.46

459.186

31690-09-2

Levomefolic acid-13C,d3;1356019-94-7;Levomefolate calcium;151533-22-1;Levomefolic acid-13C5;2687960-08-1

135398561

Light yellow to yellow solid powder

1.6±0.1 g/cm3

1.733

-2.61

202.77

7

10

9

33

865

2

CN1[C@H](CNC2=C1C(=O)NC(=N2)N)CNC3=CC=C(C=C3)C(=O)N[C@@H](CCC(=O)O)C(=O)O

ZNOVTXRBGFNYRX-STQMWFEESA-N

InChI=1S/C20H25N7O6/c1-27-12(9-23-16-15(27)18(31)26-20(21)25-16)8-22-11-4-2-10(3-5-11)17(30)24-13(19(32)33)6-7-14(28)29/h2-5,12-13,22H,6-9H2,1H3,(H,24,30)(H,28,29)(H,32,33)(H4,21,23,25,26,31)/t12-,13-/m0/s1

(2S)-2-[[4-[[(6S)-2-amino-5-methyl-4-oxo-3,6,7,8-tetrahydropteridin-6-yl]methylamino]benzoyl]amino]pentanedioic acid

LMSR Levomefolinic acidLevomefolinic acid Metafolin BodyfolinNutrifolin Levomefolate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~2.08 mg/mL (~4.53 mM)

注意: 如下所列的是一些常用的体内动物实验溶解配方，主要用于溶解难溶或不溶于水的产品（水溶度<1 mg/mL）。 建议您先取少量样品进行尝试，如该配方可行，再根据实验需求增加样品量。

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注射用配方1: DMSO : Tween 80： Saline = 10 : 5 : 85 (如： 100 μL DMSO → 50 μL Tween 80 → 850 μL Saline)
*生理盐水/Saline的制备：将0.9g氯化钠/NaCl溶解在100 mL ddH ₂ O中，得到澄清溶液。
注射用配方 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL DMSO → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)
注射用配方 3: DMSO : Corn oil = 10 : 90 (如： 100 μL DMSO → 900 μL Corn oil)
示例: 以注射用配方 3 (DMSO : Corn oil = 10 : 90) 为例说明, 如果要配制 1 mL 2.5 mg/mL的工作液, 您可以取 100 μL 25 mg/mL 澄清的 DMSO 储备液，加到 900 μL Corn oil/玉米油中, 混合均匀。

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注射用配方 4: DMSO : 20% SBE-β-CD in Saline = 10 : 90 [如：100 μL DMSO → 900 μL (20% SBE-β-CD in Saline)]
*20% SBE-β-CD in Saline的制备（4°C，储存1周）：将2g SBE-β-CD (磺丁基-β-环糊精) 溶解于10mL生理盐水中，得到澄清溶液。
注射用配方 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (如： 500 μL 2-Hydroxypropyl-β-cyclodextrin (羟丙基环胡精)→ 500 μL Saline)
注射用配方 6: DMSO : PEG300 : Castor oil : Saline = 5 : 10 : 20 : 65 (如： 50 μL DMSO → 100 μL PEG300 → 200 μL Castor oil → 650 μL Saline)
注射用配方 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (如： 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
注射用配方 8: 溶解于Cremophor/Ethanol (50 : 50), 然后用生理盐水稀释。
注射用配方 9: EtOH : Corn oil = 10 : 90 (如： 100 μL EtOH → 900 μL Corn oil)
注射用配方 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL EtOH → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)

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口服配方 1: 悬浮于0.5% CMC Na (羧甲基纤维素钠)
口服配方 2: 悬浮于0.5% Carboxymethyl cellulose (羧甲基纤维素)
示例: 以口服配方 1 (悬浮于 0.5% CMC Na)为例说明, 如果要配制 100 mL 2.5 mg/mL 的工作液, 您可以先取0.5g CMC Na并将其溶解于100mL ddH2O中，得到0.5%CMC-Na澄清溶液；然后将250 mg待测化合物加到100 mL前述 0.5%CMC Na溶液中，得到悬浮液。

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口服配方 3: 溶解于 PEG400 (聚乙二醇400)
口服配方 4: 悬浮于0.2% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 5: 溶解于0.25% Tween 80 and 0.5% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 6: 做成粉末与食物混合

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注意: 以上为较为常见方法，仅供参考， InvivoChem并未独立验证这些配方的准确性。具体溶剂的选择首先应参照文献已报道溶解方法、配方或剂型，对于某些尚未有文献报道溶解方法的化合物，需通过前期实验来确定（建议先取少量样品进行尝试），包括产品的溶解情况、梯度设置、动物的耐受性等。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。