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|Section2= |Section3= }} Canthaxanthin is a keto-carotenoid〔Efficient Syntheses of the Keto-carotenoids Canthaxanthin, Astaxanthin, and Astacene. Seyoung Choi and Sangho Koo, J. Org. Chem., 2005, 70 (8), pages 3328–3331, 〕 pigment widely distributed in nature. Carotenoids belong to a larger class of phytochemicals known as terpenoids. The chemical formula of canthaxanthin is C40H52O2.〔(Opinion on the use of canthaxanthin in feedingstuffs for salmon ... )〕 It was first isolated in edible mushrooms. It has also been found in green algae, bacteria, crustaceans, and bioaccumulates in fish such as carp, golden mullet, seabream and trush wrasse.〔 Canthaxanthin is associated with E number E161g and is approved for use as a food coloring agent in different countries, including the United States〔(【引用サイトリンク】title=Colour Additive Status List )〕 and the EU; however, it is not approved for use in Australia and New Zealand.〔(【引用サイトリンク】title=Standard 1.2.4 - Labelling of ingredients )〕 It is generally authorized for feed applications in at least the following countries: USA,〔(【引用サイトリンク】title=Code of Federal Regulations Title 21, 1 April 2012 )〕 Canada,〔(【引用サイトリンク】title=Feeds Regulations, 1983 (SOR/83-593) )〕 EU.〔(【引用サイトリンク】title=European Union Register of Feed Additives, Revision 162 released 7 June 2013 )〕 In the EU, canthaxanthin is allowed by law to be added to trout feed, salmon feed and poultry feed. The European Union limit is 80 mg/kg of feedstuffs,〔 8 mg/kg in feed for egg laying hens and 25 mg/kg in feed for other poultry and salmonids. Canthaxanthin is a potent lipid-soluble antioxidant. The biological functions of canthaxanthin are related, at least in part, to its ability to function as an antioxidant (free radical scavenging/vitamin E sparing) in animal tissues. == Biosynthesis == Due to the commercial value of carotenoids, their biosynthesis has been studied extensively in both natural producers, and non-natural (heterologous) systems such as the bacteria ''Escherichia coli'' and yeast ''Saccharomyces cerevisiae''. Canthanaxanthin biosynthesis proceeds from beta-carotene via the action of a single protein, known as a beta-carotene ketolase, that is able to add a carbonyl group to carbon 4 and 4' of the beta carotene molecule. Although functionally identical, several distinct beta-carotene ketolase proteins are known. That is to say they differ from an evolutionary perspective in their primary amino acid/protein sequence. They are different proteins that complete the same function. Thus, bacterial (CrtW) and micro-algal beta-carotene ketolase proteins such as ''BKT'' isolated from ''Haematococcus pluvialis'' are known. Due to the nature of canthaxanthin, relative to astaxanthin (a carotenoid of significant commercial value) these beta-carotene ketolase proteins have been studied extensively. An ''E. coli'' based production system has been developed, that achieved canthanaxanthin production at 170 mg/l in lab scale fermentation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Canthaxanthin」の詳細全文を読む スポンサード リンク
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