Vitamer
Encyclopedia
A vitamer of a particular vitamin
is any of a number of chemical substances, each of which shows vitamin activity. Very commonly each "vitamin" is not a single chemical, but rather multiple chemical substances called vitamers, each of which is defined by its different biological activity.
For instance, Vitamin A
has six vitamer chemicals that all qualify as vitamin A, each with slightly different properties. Four of them are carotenes, from plant foods like carrots, but the retinol
form, from animal foods, is several times as effective in humans, per microgram, than the carotene forms. The carotene forms also cannot be absorbed by cats at all.
Typically, the vitamin activity of multiple vitamers is due to the body's (limited) ability to convert one vitamer to another, or many vitamers to the same enzymatic cofactor
(s), which is active in the body as the important form of the vitamin.
As part of the definition of vitamin, the body cannot completely synthesize an optimal amount of vitamin activity from simple foodstuffs, without some minimal amount of a vitamer molecule as a basis.
Typically not all vitamers possess exactly the same vitamin potency, per mass. This is due to differences in absorption and interconversion of the various vitamers of a vitamin. Often for the same reason, the toxicity of vitamers varies by molecule, as is the case with vitamin E.
A set of chemicals may be (but is not always) grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A". Other examples of vitamers include cyanocobalamin
, hydroxocobalamin
, methylcobalamin, and 5-deoxyadenosylcobalamin (adenosylcobalamin—AdoB-12), which are all vitamers of B12, and thus all possess "B12 activity". Another example is that both niacinamide and nicotinic acid (niacin) have vitamin B3 activity.
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
is any of a number of chemical substances, each of which shows vitamin activity. Very commonly each "vitamin" is not a single chemical, but rather multiple chemical substances called vitamers, each of which is defined by its different biological activity.
For instance, Vitamin A
Vitamin A
Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...
has six vitamer chemicals that all qualify as vitamin A, each with slightly different properties. Four of them are carotenes, from plant foods like carrots, but the retinol
Retinol
Retinol is one of the animal forms of vitamin A. It is a diterpenoid and an alcohol. It is convertible to other forms of vitamin A, and the retinyl ester derivative of the alcohol serves as the storage form of the vitamin in animals....
form, from animal foods, is several times as effective in humans, per microgram, than the carotene forms. The carotene forms also cannot be absorbed by cats at all.
Typically, the vitamin activity of multiple vitamers is due to the body's (limited) ability to convert one vitamer to another, or many vitamers to the same enzymatic cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
(s), which is active in the body as the important form of the vitamin.
As part of the definition of vitamin, the body cannot completely synthesize an optimal amount of vitamin activity from simple foodstuffs, without some minimal amount of a vitamer molecule as a basis.
Typically not all vitamers possess exactly the same vitamin potency, per mass. This is due to differences in absorption and interconversion of the various vitamers of a vitamin. Often for the same reason, the toxicity of vitamers varies by molecule, as is the case with vitamin E.
A set of chemicals may be (but is not always) grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A". Other examples of vitamers include cyanocobalamin
Cyanocobalamin
Cyanocobalamin is an especially common vitamer of the vitamin B12 family. It is the most famous vitamer of the family, because it is, in chemical terms, the most air-stable...
, hydroxocobalamin
Hydroxocobalamin
Hydroxocobalamin is a natural form, or vitamer, of vitamin B12, a basic member of the cobalamin family of compounds. Hydroxocobalamin is the form of vitamin B12 produced by many bacteria which are used to produce the vitamin commercially. Like other forms of vitamin B12, hydroxocobalamin has an...
, methylcobalamin, and 5-deoxyadenosylcobalamin (adenosylcobalamin—AdoB-12), which are all vitamers of B12, and thus all possess "B12 activity". Another example is that both niacinamide and nicotinic acid (niacin) have vitamin B3 activity.
List of vitamins by generic descriptor, with some of their vitamers including active forms
| Vitamin generic descriptor name | Vitamer chemical name(s) or chemical class of compounds (list not complete) |
|---|---|
| Vitamin A Vitamin A Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision... |
Retinol Retinol Retinol is one of the animal forms of vitamin A. It is a diterpenoid and an alcohol. It is convertible to other forms of vitamin A, and the retinyl ester derivative of the alcohol serves as the storage form of the vitamin in animals.... , retinal Retinal Retinal, also called retinaldehyde or vitamin A aldehyde, is one of the many forms of vitamin A . Retinal is a polyene chromophore, and bound to proteins called opsins, is the chemical basis of animal vision... , and four carotenoid Carotenoid Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building... s: the carotene Carotene The term carotene is used for several related unsaturated hydrocarbon substances having the formula C40Hx, which are synthesized by plants but cannot be made by animals. Carotene is an orange photosynthetic pigment important for photosynthesis. Carotenes are all coloured to the human eye... s alpha-carotene Alpha-carotene α-Carotene is a form of carotene with a β-ring at one end and an ε-ring at the other. It is the second most common form of carotene.-Human physiology:... , beta-carotene Beta-carotene β-Carotene is a strongly-coloured red-orange pigment abundant in plants and fruits. It is an organic compound and chemically is classified as a hydrocarbon and specifically as a terpenoid , reflecting its derivation from isoprene units... , gamma-carotene; and the xanthophyll Xanthophyll Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments... beta-cryptoxanthin Cryptoxanthin Cryptoxanthin is a natural carotenoid pigment. It has been isolated from a variety of sources including the petals and flowers of plants in the genus Physalis, orange rind, papaya, egg yolk, butter, apples, and bovine blood serum.-Chemistry:... |
| Vitamin B1 Thiamine Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are... |
Thiamine Thiamine Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are... , Thiamine pyrophosphate Thiamine pyrophosphate Thiamine pyrophosphate , or thiamine diphosphate , is a thiamine derivative which is produced by the enzyme thiamine pyrophosphatase. Thiamine pyrophosphate is a coenzyme that is present in all living systems, in which it catalyzes several biochemical reactions... |
| Vitamin B2 Riboflavin Riboflavin, also known as vitamin B2 or additive E101, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals. It is the central component of the cofactors FAD and FMN, and is therefore required by all flavoproteins. As such, vitamin B2 is required for a... |
Riboflavin Riboflavin Riboflavin, also known as vitamin B2 or additive E101, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals. It is the central component of the cofactors FAD and FMN, and is therefore required by all flavoproteins. As such, vitamin B2 is required for a... , Flavin mononucleotide Flavin mononucleotide Flavin mononucleotide , or riboflavin-5′-phosphate, is a biomolecule produced from riboflavin by the enzyme riboflavin kinase and functions as prosthetic group of various oxidoreductases including NADH dehydrogenase as well as cofactor in biological blue-light photo receptors... (FMN), Flavin adenine dinucleotide (FAD) |
| Vitamin B3 Niacin "Niacin" redirects here. For the neo-fusion band, see Niacin .Niacin is an organic compound with the formula and, depending on the definition used, one of the forty to eighty essential human nutrients.Niacin is one of five vitamins associated with a pandemic deficiency disease: niacin deficiency... |
Niacin Niacin "Niacin" redirects here. For the neo-fusion band, see Niacin .Niacin is an organic compound with the formula and, depending on the definition used, one of the forty to eighty essential human nutrients.Niacin is one of five vitamins associated with a pandemic deficiency disease: niacin deficiency... , niacinamide |
| Vitamin B5 Pantothenic acid Pantothenic acid, also called pantothenate or vitamin B5 , is a water-soluble vitamin. For many animals, pantothenic acid is an essential nutrient. Animals require pantothenic acid to synthesize coenzyme-A , as well as to synthesize and metabolize proteins, carbohydrates, and fats.Pantothenic acid... |
Pantothenic acid Pantothenic acid Pantothenic acid, also called pantothenate or vitamin B5 , is a water-soluble vitamin. For many animals, pantothenic acid is an essential nutrient. Animals require pantothenic acid to synthesize coenzyme-A , as well as to synthesize and metabolize proteins, carbohydrates, and fats.Pantothenic acid... |
| Vitamin B6 Vitamin B6 Vitamin B6 is a water-soluble vitamin and is part of the vitamin B complex group. Several forms of the vitamin are known, but pyridoxal phosphate is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation... |
Pyridoxine Pyridoxine Pyridoxine is one of the compounds that can be called vitamin B6, along with pyridoxal and pyridoxamine. It differs from pyridoxamine by the substituent at the '4' position. It is often used as 'pyridoxine hydrochloride'.-Chemistry:... , pyridoxamine Pyridoxamine Pyridoxamine is a vitamer in the vitamin B6 family, which includes pyridoxal and pyridoxine. Pyridoxamine is converted to the biologically active form of vitamin B6, pyridoxal 5-phosphate, via the vitamin B6 salvage pathway. Vitamin B6 acts as an enzyme cofactor in a variety of metabolic processes... , pyridoxal Pyridoxal Pyridoxal is one of the three natural forms of vitamin B6, along with pyridoxamine and pyridoxine . All of these forms are converted in the human body into a single biologically active form, pyridoxal 5-phosphate. All three forms of vitamin B6 are heterocyclic organic compounds... , pyridoxal 5-phosphate |
| Vitamin B7 Biotin Biotin, also known as Vitamin H or Coenzyme R, is a water-soluble B-complex vitamin discovered by Bateman in 1916. It is composed of a ureido ring fused with a tetrahydrothiophene ring. A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring... |
Biotin Biotin Biotin, also known as Vitamin H or Coenzyme R, is a water-soluble B-complex vitamin discovered by Bateman in 1916. It is composed of a ureido ring fused with a tetrahydrothiophene ring. A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring... |
| Vitamin B9 Folic acid Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9... |
Folic acid Folic acid Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9... , folinic acid Folinic acid Folinic acid or leucovorin , generally administered as calcium or sodium folinate , is an adjuvant used in cancer chemotherapy involving the drug methotrexate. It is also used in synergistic combination with the chemotherapy agent 5-fluorouracil.Levofolinic acid and its salts are the enantiopure... , 5-Methyltetrahydrofolate 5-Methyltetrahydrofolate Levomefolic acid or metafolin is the natural, active form of folic acid used at the cellular level for DNA reproduction, the cysteine cycle and the regulation of homocysteine among other functions. The un-methylated form, folic acid , is a synthetic form of folate found in nutritional supplements... |
| Vitamin B12 Vitamin B12 Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins... |
Cyanocobalamin Cyanocobalamin Cyanocobalamin is an especially common vitamer of the vitamin B12 family. It is the most famous vitamer of the family, because it is, in chemical terms, the most air-stable... , hydroxocobalamin Hydroxocobalamin Hydroxocobalamin is a natural form, or vitamer, of vitamin B12, a basic member of the cobalamin family of compounds. Hydroxocobalamin is the form of vitamin B12 produced by many bacteria which are used to produce the vitamin commercially. Like other forms of vitamin B12, hydroxocobalamin has an... , methylcobalamin, adenosylcobalamin |
| Vitamin C Vitamin C Vitamin C or L-ascorbic acid or L-ascorbate is an essential nutrient for humans and certain other animal species. In living organisms ascorbate acts as an antioxidant by protecting the body against oxidative stress... |
Ascorbic acid Ascorbic acid Ascorbic acid is a naturally occurring organic compound with antioxidant properties. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Ascorbic acid is one form of vitamin C. The name is derived from a- and scorbutus , the... , calcium ascorbate Calcium ascorbate Calcium ascorbate is a compound with the molecular formula CaC12H14O12. It is the calcium salt of ascorbic acid, one of the mineral ascorbates.... , sodium ascorbate Sodium ascorbate Sodium ascorbate is a more bioavailable form of vitamin C that is an alternative to taking ascorbic acid as a supplement. The molecular formula of this chemical compound is C6H7NaO6... , other salts of ascorbic acid |
| Vitamin D Vitamin D Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate .... |
ergocalciferol Ergocalciferol Ergocalciferol is a form of vitamin D, also called vitamin D2. It is marketed under various names including Deltalin , Drisdol and Calcidol... (D2), cholecalciferol Cholecalciferol Cholecalciferol is a form of vitamin D, also called vitamin D3 or calciol.It is structurally similar to steroids such as testosterone, cholesterol, and cortisol .-Forms:Vitamin D3 has several forms:... (D3) |
| Vitamin E Vitamin E Vitamin E is used to refer to a group of fat-soluble compounds that include both tocopherols and tocotrienols. There are many different forms of vitamin E, of which γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings... |
Tocopherol Tocopherol Tocopherols are a class of chemical compounds of which many have vitamin E activity. It is a series of organic compounds consisting of various methylated phenols... s (d-alpha, d-beta, d-gamma, and d-delta-tocopherol), tocotrienol Tocotrienol Tocotrienols are members of the vitamin E family. An essential nutrient for the body, vitamin E is made up of four tocopherols and four tocotrienols . The slight difference between tocotrienols and tocopherols lie in the unsaturated side chain having three double bonds in its farnesyl isoprenoid... s |
| Vitamin K Vitamin K Vitamin K is a group of structurally similar, fat soluble vitamins that are needed for the posttranslational modification of certain proteins required for blood coagulation and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4-naphthoquinone derivatives... |
phylloquinone Phylloquinone Phylloquinone is a polycyclic aromatic ketone, based on 2-methyl-1,4-naphthoquinone, with a 3-phytyl substituent.It is a fat-soluble vitamin that is stable to air and moisture but decomposes in sunlight. It is found naturally in a wide variety of green plants.-Terminology:It is often called... (K1), menaquinones (K2) |