Methylcobalamin

Methylcobalamin
Systematic (IUPAC) name


carbanide; cobalt(3+);
Clinical data
AHFS/Drugs.com
Legal status	US: OTC
Routes of administration	oral,sublingual,injection.
Identifiers
CAS Registry Number	^Y
ATC code	B03
PubChem	CID:
UNII	^N
ChEMBL	^N
Chemical data
Formula	C₆₃H₉₁Co N₁₃O₁₄P
Molecular mass	1344.40 g/mol
N

Methylcobalamin (mecobalamin, MeCbl, or MeB₁₂) is a cobalamin, a form of vitamin B₁₂. It differs from cyanocobalamin in that the cyanide is replaced by a methyl group.^[1] Methylcobalamin features an octahedral cobalt(III) centre. Methylcobalamin can be obtained as bright red crystals.^[2] From the perspective of coordination chemistry, methylcobalamin is notable as a rare example of a compound that contains metal-alkyl bonds. Nickel-methyl intermediates have been proposed for the final step of methanogenesis.

Methylcobalamin is equivalent physiologically to vitamin B₁₂, and can be used to prevent or treat pathology arising from a lack of vitamin B₁₂ (vitamin B12 deficiency), such as pernicious anemia.

Methylcobalamin is also used in the treatment of peripheral neuropathy, diabetic neuropathy, and as a preliminary treatment for amyotrophic lateral sclerosis.

Production 1
Functions 2
See also 3
References 4

Production

Methylcobalamin physically resembles the other forms of vitamin B₁₂, occurring as dark red crystals that freely form cherry-colored transparent solutions in water.

Methylcobalamin can be produced in the laboratory by reducing cyanocobalamin with sodium borohydride in alkaline solution, followed by the addition of methyl iodide.^[2]

Functions

This vitamer is one of two active coenzymes used by vitamin B₁₂-dependent enzymes and is the specific vitamin B₁₂ form used by 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), also known as methionine synthase.

Methylcobalamin participates in the

Categories

Enzyme cofactors

Active forms

vitamins	TPP / ThDP (B₁) FMN, FAD (B₂) NAD⁺, NADH, NADP⁺, NADPH (B₃) Coenzyme A (B₅) PLP / P5P (B₆) Biotin (B₇) THFA / H₄FA, DHFA / H₂FA, MTHF (B₉) AdoCbl, MeCbl (B₁₂) Ascorbic acid (C) Phylloquinone (K₁), Menaquinone (K₂) Coenzyme F420

non-vitamins	ATP CTP SAMe PAPS GSH Coenzyme B Cofactor F430 Coenzyme M Coenzyme Q Heme / Haem (A, B, C, O) Lipoic Acid Methanofuran Molybdopterin/Molybdenum cofactor PQQ THB / BH₄ THMPT / H₄MPT

minerals	Ca²⁺ Cu²⁺ Fe²⁺, Fe³⁺ Mg²⁺ Mn²⁺ Mo Ni²⁺ Zn²⁺

Base forms

vitamins: see

Index of nutrition

Description	Fats Sugars

Disease

Treatment	Drugs

Vitamins (A11)

Fat soluble

A	α-Carotene β-Carotene Retinol^# Tretinoin

D	D₂ Ergosterol Ergocalciferol^# D₃ 7-Dehydrocholesterol Previtamin D₃ Cholecalciferol 25-hydroxycholecalciferol Calcitriol (1,25-dihydroxycholecalciferol) Calcitroic acid D₄ Dihydroergocalciferol D₅ D analogues Alfacalcidol Dihydrotachysterol Calcipotriol Tacalcitol Paricalcitol

E	Tocopherol Alpha Beta Gamma Delta Tocotrienol Alpha Beta Gamma Delta Tocofersolan

K	Naphthoquinone Phylloquinone (K₁) Menaquinones (K₂) Menadione (K₃)‡ Menadiol (K₄)

Water soluble

B	B₁ Thiamine^# B₁ analogues Acefurtiamine Allithiamine Benfotiamine Fursultiamine Octotiamine Prosultiamine Sulbutiamine B₂ Riboflavin^# B₃ Niacin Nicotinamide^# B₅ Pantothenic acid Dexpanthenol Pantethine B₆ Pyridoxine^#, Pyridoxal phosphate Pyridoxamine Pyritinol B₇ Biotin B₉ Folic acid Dihydrofolic acid Folinic acid Levomefolic acid B₁₂ Cyanocobalamin Hydroxocobalamin Methylcobalamin Cobamamide Choline

C	Ascorbic acid^# Dehydroascorbic acid

Combinations

Multivitamins

^#WHO-EM
^‡Withdrawn from market
Clinical trials:
- ^†Phase III
- ^§Never to phase III

Index of nutrition

Description	Fats Sugars

Disease

Treatment	Drugs

^ L. R. McDowell, Vitamins in animal and human nutrition
^ ^a ^b David Dophin. Preparation of the Reduced Forms of Vitamin B₁₂ and of Some Analogs of the Vitamin B₁₂ Coenzyme Containing a Cobalt-Carbon Bond. D.B. McCormick and L.D. Wright, Eds. 1971;Vol. XVIII:34-54.
^ Fontecilla-Camps, J. C.; Amara, P.; Cavazza, C.; Nicolet, Y.; Volbeda, A. (2009). "Structure–function relationships of anaerobic gas-processing metalloenzymes". Nature 460 (7257): 814–822.
^ Zenon Schneider, Andrzej Stroiński, Comprehensive B12: Chemistry, Biochemistry, Nutrition, Ecology, Medicine
^ Bémeur, Chantal; et al. (2011). Blass, John P., ed. Neurochemical Mechanisms in Disease. Springer. pp. 112–3.

References

Methylcobalamin is produced by some bacteria. It plays an important role in the environment. In the environment, it is responsible for the biomethylation of certain heavy metals. For example, the highly toxic methylmercury is produced by the action of methylcobalamin.^[4] In this role, methylcobalamin serves as a source of "CH₃⁺".

[3]

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Methylcobalamin