Astaxanthin free

Astaxanthin free Astaxanthin ester Can tax an thin Echinenone /1-carotene Other carotene... 

Astaxanthin was detected at 480 nm. The chromatographic profiles of microencapsulated and free astaxanthin after eight weeks of storage are shown in Fig. 2.36. It was concluded from the results that the method is suitable for the study of the stability of miroencapsulated astaxanthin. The HPLC data proved that microencapculated as (ax an h tin did not suffer isomerization or chemical decomposition under the experimental conditions [79],... 

Conversion of steryl esters and astaxanthin esters to their free... 

Conversion of Steryl Esters and Astaxanthin Esters to Their Free Forms... 

Lipase-catalyzed conversion of FAStEs to sterols in the presence of MeOH was applied to astaxanthin FA esters to free astaxanthin, because a screening test showed that commercial lipases did not hydrolyze astaxanthin FA esters. A mixture of astaxanthin and its mono- and diesters (5 80 15, by mol) was treated in the presence of 50wt% water with 5 mol EtOH for FAs in astaxanthin esters using P. aeruginosa lipase. After the reaction, the molar ratio of astaxanthin and its mono- and diesters was 89 10 1, showing that the lipase efficiently converts astaxanthin esters to free astaxanthin. The free form was also purified by n-hexane fractionation with 69% recovery of the initial content of astaxanthin in the mixture of its free and ester forms (Nagao et al., 2003). 

In nature, astaxanthin is usually found either conjugated to proteins (as in the flesh of salmon or in the lobster carapace) or esterified with fatty acids (as in Haematococcus pluvialis microalgae). In contrast, synthetic astaxanthin is produced in the free form. Synthetic, algae-based, and yeast-based (from Xanthophyllomyces dendrorhous) astaxanthins are distinct in their stereoisomeric compositions as well." Synthetic astaxanthin, as well as all three significant natural sources Haematococcus, Xanthophyllomyces, and extracted cmstacean shells), are used widely as feed additives." Human dietary astaxanthin supplements derived from these three natural sources have also been marketed in recent years. " ... 

Bagchi, D., Oxygen free radical scavenging abilities of vitamins C, E, P-carotene, pycnogenol, grape seed proanthocyanidin extract, astaxanthin and BioAstin in vitro, Final Report to Cyanotech Corporation, Creighton University School of Health Sciences, Omaha, NE, 2001. 

Uchiyama, K. et al.. Beneficial effects of astaxanthin in type 2 diabetes model of db/db mouse. Free Radical Biol. Med., 33, S211, 2002. 

The middle part is always a conjugated polyene (symmetrical or unsymmetrical) and can be prepared by a number of established methods which are discussed in detail in Chapter 3 Part I. Some of these middle parts are readily available more common ones, e.g. the Cio-dialdehyde, are manufactured on a ton scale as industrial intermediates for the technical syntheses of (3,(3-carotene (3) and astaxanthin (406). For the synthesis of unsymmetrical carotenoids, the Cio-dialdehyde can be converted into a monoacetal derivative. The free aldehyde moiety is coupled with one end group, and the intermediate product is deprotected and then combined with the second end group. In these reactions, there are some positions which permit a coupling in high yield [C(9)-C(10) and C(11)-C(12)] and others [C(7)-C(8)] which, for cyclic carotenoids, give products in only low yield because of steric hindrance due to the adjacent methyl groups. The choice of the middle part and its synthesis has become a simple matter today. 

Analogously, (3/ ,3 / )-zeaxanthin (119) is prepared from the corresponding sulphone 36b which possesses a free hydroxy group. On the other hand, protected sulphones, 36e and 36f, should be employed for obtaining canthaxanthin (380) and astaxanthin (403), respectively, because dithionites reduce the keto groups. 

Astaxanthin (403) can be obtained from 380 by two routes, in both of which the bis-enolate 47 is produced by reaction with lithium diisopropylamide or sodium hexamethyl-disilazane. In the first method, 47 is converted into the bis-silyl enol ether (48) which, after oxidation with peroxyacids, rearrangement to give the astaxanthin bis-silyl ether and acid-catalysed cleavage of the silyl groups, yields free 403 [31]. Alternatively, 47 can be oxidized directly to 403 by reaction with l-phenylsulphonyl-2-phenyloxaziridine [32] (Scheme 10). 

Astaxanthin (k ax = 472 nm) is the typical colourant of lobster. In live animals, astaxanthin is complexed by proteins. The absorption maximum of these complexes lies at 587 and 632 nm, so that the animals appear blue. When lobster is cooked, the protein complexes are destroyed and the red colour of free astaxanthin becomes evident. 

The principal pigments of crustacean hemolymph and egg lipoproteins are j8-carotene, astaxanthin, and canthaxanthin. There is generally a shift in the maximum in the carotenoid bound to the lipoprotein relative to the maximum of the free carotenoid. 

Not all carotenoids are vitamin A precursors - they comprise 90% of carotenoids, nevertheless they are excellent free radical scavengers. Examples are lycopene (in tomatoes) and astaxanthin (Fig. 51.2). The latter is enjoying a reputation as a nutriceutical it is pink and found in aquatic animals, e.g. salmon, shrimp and lobster, and in the alga, Haematococcus pluvialis, from which it is commercially extracted. 

The red pigment of salmonid fish and many crustaceans (shrimps, crabs, crayfish and others) is xanthophyll astaxanthin, (3S,3S )-astaxanthin, which is (3S,3S )-P,P-carotene-3,3 -dihydroxy-4,4 -dione (9-192). Astaxanthin in crustaceans is bound to proteins in dark blue-red and green-red carotenoproteins. During cooking, proteins denature and the typical red colour of free astaxanthin becomes more vibrant For example, the light blue crab Homarus gammarus (Nephropidae), known as European lobster... 

Some carotenoids are precursors (provitamins) of vitamin A. Other carotenoids, such as cryptoxanthin, zeaxanthin and lutein, exhibit, by contrast, about half of the activity of provitamins A. Some carotenoids, such as lycopene, astaxanthin and canthaxanthin, are more effective in quenching singlet oxygen than P-carotene. Carotenoids also react with free radicals such as P-carotene. Because of their antioxidative properties, they are used in the prevention of degenerative processes and as anticancer agents. 

Because the lobster accumulates a combination of protein-bound (blue) and free (red) astaxanthin in its shell, the live animal appears greenish-brown, which apparently serves it well as a disguise against... 

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