The name vitamin B12 is used in two different ways. In a broad sense it refers to a group of cobalt-containing compounds known as cobalamins - cyanocobalamin (an artifact formed as a result of the use of cyanide in the purification procedures), hydroxocobalamin and the two coenzyme forms of B12, methylcobalamin (MeB12) and 5-deoxyadenosylcobalamin (adenosylcobalamin - AdoB12). In a more specific way, the term B12 is used to refer to only one of these forms, cyanocobalamin, which is the principal B12 form used for foods and in nutritional supplements. B12 cannot be made by plants or by animals, as the only type of organisms that have the enzymes required for the synthesis of B12 are bacteria and archaea. The total synthesis of B12 was reported in 1973 by Robert Burns Woodward, and remains one of the classic feats of total synthesis. Cyanocobalamin is a vitamin commonly known as vitamin B12 (or B12 for short).
λ²-cobalt(2+) ion 1-[(2S,3R,4S,5R)-3-hydroxy-4-{[hydroxy({[(2R)-1-({1-hydroxy-3-[(1R,2R,3R,4R,8S,13S,14S,18S,19S)-8,13,18-tris(2-carboximidatoethyl)-3,14,19-tris[(C-hydroxycarbonimidoyl)methyl]-1,4,6,9,9,14,16,19-octamethyl-20,21,22,23-tetraazapentacyclo[15.2.1.1²,⁵.1⁷,¹⁰.1¹²,¹⁵]tricosa-5(23),6,10(22),11,15(21),16-hexaen-4-yl]propylidene}amino)propan-2-yl]oxy})phosphoryl]oxy}-5-(hydroxymethyl)oxolan-2-yl]-5,6-dimethyl-3H-1λ⁵,3-benzodiazol-1-ylium methane
Traditional Name
λ²-cobalt(2+) ion 1-[(2S,3R,4S,5R)-3-hydroxy-4-{[hydroxy([(2R)-1-({1-hydroxy-3-[(1R,2R,3R,4R,8S,13S,14S,18S,19S)-8,13,18-tris(2-carboximidatoethyl)-3,14,19-tris(C-hydroxycarbonimidoylmethyl)-1,4,6,9,9,14,16,19-octamethyl-20,21,22,23-tetraazapentacyclo[15.2.1.1²,⁵.1⁷,¹⁰.1¹²,¹⁵]tricosa-5(23),6,10(22),11,15(21),16-hexaen-4-yl]propylidene}amino)propan-2-yl]oxy)phosphoryl]oxy}-5-(hydroxymethyl)oxolan-2-yl]-5,6-dimethyl-3H-1λ⁵,3-benzodiazol-1-ylium methane
belongs to the class of organic compounds known as cobalamin derivatives. These are organic compounds containing a corrin ring, a cobalt atom, an a nucleotide moiety. Cobalamin Derivatives are actually derived from vitamin B12.
Cobalt is believed to exhibit its toxicity through a oxidant-based and free radical-based processes. It produces oxygen radicals and may be oxidized to ionic cobalt, causing increased lipid peroxidation, DNA damage, and inducing certain enzymes that lead to cell apoptosis. Cobalt has also been shown to block inorganic calcium channels, possibly impairing neurotransmission. Cobalt can also chelate lipoic acids, impairing oxidation of pyruvate or fatty acids. In addition, cobalt may inhibit DNA repair by interacting with zinc finger DNA repair proteins, and has also been shown to inhibit heme synthesis and glucose metabolism. Cobalt may activate specific helper T-lymphocyte cells and interact directly with immunologic proteins, such as antibodies (IgA and IgE) or Fc receptors, resulting in immunosensitization. (11)
Metabolism
Cobalt is absorbed though the lungs, gastrointestinal tract, and skin. Since it is a component of the vitamin B12 (cyanocobalamin), it is distributed to most tissues of the body. It is transported in the blood, often bound to albumin, with the highest levels being found in the liver and kidney. Cobalt is excreted mainly in the urine and faeces. (11)
Exposure to high amount of cobalt can cause heart, lung, kidney, and liver damage. Skin contact is known to result in contact dermatitis. Cobalt may also have mutagenic and carcinogenic effects. (11, 12)
Symptoms
Cobalt inhalation can cause asthma-like breathing problems. Skin contact is known to result in contact dermatitis, which is characterized by irritation and rashes. Ingesting large amounts of cobalt may cause nausea and vomiting. (16)
Treatment
Treatment of cobalt poisoning is symptomatic. (11)
