Scientists have identified a novel group of arsenic-containing compounds in fish oil that may have an unusual biosynthetic origin. Kevin Francesconi at Karl-Franzens University, Graz, Austria, and colleagues found three arsenic-containing lipids in the oil from capelin fish found in the North Atlantic. They used mass spectrometry and chromatography to identify the structures of the compounds and were surprised by the results.
Naturally occurring hydrocarbons usually contain an odd number of carbon atoms because they are made by overall decarboxylation of long-chain fatty acids that contain even numbers of carbons. But Francesconi showed that the arsenolipids contained an even number of carbon atoms. 'The work raises questions about how and why these compounds are biosynthesised, and what the human health consequences are when they are consumed,' says Francesconi.
Francesconi points out that nutritionists encourage people to eat fish oils and oily fish because they contain high levels of polyunsaturated lipids but human metabolism of arsenolipids has not been studied. 'Human exposure to arsenic through food has received little attention,' he says. 'We are working to identify, quantify and toxicologically assess arsenic compounds in food. Fat soluble arsenicals in fish oils and in oily fish are a new and important part of this research.'
Original article: Mojtaba S. Taleshi, Chem. Commun., 2008.