Arsenocholine

Structural formula
Cation ( anion not shown)
General
Surname	Arsenocholine
other names	2-hydroxyethyl trimethylarsonium ( IUPAC ) Fish arsenic
Molecular formula	C 5 H 14 AsO +
External identifiers / databases
CAS number 39895-81-3 PubChem 104820 Wikidata Q704767
properties
Molar mass	165.09 g mol −1
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 331-301-410 P: ?
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Arsenocholine is an organic arsenic compound in which the quaternary nitrogen of the choline has been formally replaced by arsenic . The first indications of organic arsenic compounds in oils of marine origin were found in 1968. The main representatives of organic arsenic compounds in marine life besides arsenocholine (AC) are arsenobetaine (AB), trimethylarsine oxide (TMAO) and tetramethylarsonium (TETRA).

Occurrence

Arsenocholine is found in fish and seafood (fish arsenic). These can produce organic arsenic compounds themselves, but it is believed that the primary source is lower organisms such as algae and crustaceans . In experiments in which the marine alga Tetraselmis chuii and daphnia ( Daphnia magna ) grew in the presence of arsenate , various organic arsenic compounds could be detected. Arsenocholine was postulated here as the arsenocholine residue of lipids .

properties

Physiology and Toxicology

Like choline, arsenocholine undergoes a number of biotransformations in the mitochondria of the liver. Arsenobetaine aldehyde , arsenobetaine , trimethylarsine oxide and trimethylarsine could be detected as the resulting products using cell extracts in vitro . Arsenobetaine was the main metabolite and arose from arsenobetaine aldehyde. Trimethylarsine oxide was also formed from arsenobetaine aldehyde through a side reaction. Its further reduction leads to the formation of trimethylarsine. A cytotoxicity of arsenocholine could not be demonstrated in isolated hepatocytes.

Arsenocholine administered orally to rodents (mouse, rat, rabbit) was completely absorbed in the gastrointestinal tract and 70 to 80% excreted with the urine , mainly as arsenobetaine, within 3 days . Arsenocholine itself was found in the urine only 1 day after administration. No formation of inorganic arsenic, mono- or dimethyl arsenic acid or, in contrast to the in vitro experiments described, trimethyl arsenic was observed. Administered but not excreted arsenic was found in the tissue of the animals in the form of arsenobetaine and arsenophospholipids . The longest retention times were observed for the following tissues: prostate , epididymis , testes , myocardium , liver , adrenal cortex , pancreas , tooth pulp and pituitary gland .

In the presynaptic nerve endings of cholinergic synapses, arsenocholine like choline can be absorbed, acetylated and then released as acetylarsenocholine, which can activate postsynaptic receptors and is cleaved again by acetylcholinesterase . In this respect, arsenocholine is a false cholinergic transmitter.

proof

As with arsenobetaine, arsenocholine is detected by a combination of liquid chromatographic and mass spectrometric ( ICP-MS , ESI-MS ) methods.

See also

• Arsenobetaine

Individual evidence

1. ↑ Entry on arsenic compounds in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry arsenic compounds, with the exception of those named in this appendix in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
3. ↑ G. Lunde: Analysis of arsenic in marine oils by neutron activation. Evidence of arseno organic compounds. In: J Am Oil Chem Soc . 1968 May; 45 (5): 331-332, PMID 5655522 .
4. ↑ KJ Irgolic et al. : Characterization of arsenic compounds formed by Daphnia magna and Tetraselmis chuii from inorganic arsenate. Environ Health Perspect . 1977 August; 19: 61-66, PMID 908314 ; PMC 1637411 (free full text).
5. ↑ PJG Mann et al. : Hepatic oxidation of choline and arsenocholine Biochem J. 1938 June; 32 (6): 1024-1032, PMID 16746711 ; PMC 1264144 (free full text).
6. ↑ A. Christakopoulos et al. : Cellular metabolism of arsenocholine. J Appl Toxicol . 1988 Apr; 8 (2): 119-127, PMID 3288685 .
7. ↑ E. Marafante et al. : Metabolism of arsenocholine in mice, rats and rabbits. Sci Total Environ. 1984 Mar 15; 34 (3): 223-240, PMID 6719099 .
8. ↑ Hedlund, Britta & Norin, Harald & Christakopoulos, Alex & Alberts, Peteris & Bartfai, Tamas. (1982). Acetylarsenocholine: A Cholinergic Agonist. Journal of neurochemistry. 39.871-3. 10.1111 / j.1471-4159.1982.tb07973.x. ( https://www.researchgate.net/publication/16102344_Acetylarsenocholine_A_Cholinergic_Agonist ).
9. ↑ A. Hata et al. : HPLC-ICP-MS Speciation Analysis of Arsenic in Urine of Japanese Subjects without Occupational Exposure. In: Journal of Occupational Health Vol. 49 (2007), No. 3 217-223, doi : 10.1539 / joh.49.217 .
10. ↑ TD Ninh, Y. Nagashima, K. Shiomi: Quantification of seven arsenic compounds in seafood products by liquid chromatography / electrospray ionization-single quadrupole mass spectrometry (LC / ESI-MS) . Food Addit Contam. 2006, 23 (12): 1299-1307, PMID 17118873 .