Stereoisomers Of Astaxanthin Research Articles

Stereoisomers of Astaxanthin Inhibit Human Colon Cancer Cell Growth by Inducing G2/M Cell Cycle Arrest and Apoptosis.

Astaxanthin (AST) is a xanthophyll carotenoid with potential protective effects against carcinogenesis. Different stereoisomers of AST (ASTs) exist in a variety of food sources. Due to limited information on the bioactivities of ASTs, the present study investigated the inhibitory effects of ASTs on HCT116 and HT29 human colon cancer cells. ASTs investigated herein included 3S,3'S (S) from Haematococcus pluvialis, 3R,3'R (R) from Phaffia rhodozyma, and a statistical mixture (S: meso: R = 1:2:1) (M) from synthetic AST. Cell viability assay showed that ASTs all inhibited colon cancer cell growth in a time-dependent (24-72 h) and dose-dependent (4-16 μM) manner, and there was no significant difference among the IC50 values of ASTs (p > 0.05). Flow cytometry analysis indicated that ASTs induced G2/M cell cycle arrest and cellular apoptosis in cancer cells. The cell cycle arrest caused by ASTs was associated with increases in the expression levels of p21Cip1/Waf1, p27, and p53, as well as decreases in the levels of CDK4 and CDK6. Meanwhile, the apoptosis induced by ASTs was confirmed by activation of caspase-3 and PARP in the cancer cells. The results indicated that hydroxyl (OH) at C3 and C3' of terminal ring structure might not be the major factor that affects the anticancer activity of AST. This study revealed important information on the inhibitory effects of ASTs on human colon cancer cells, which provided a basis for using ASTs as chemopreventive agents for colon cancer.

Assessment and comparison of in vitro immunoregulatory activity of three astaxanthin stereoisomers

In recent years, the immune-modulatory role of all-trans astaxanthin from different pigment sources has been studied. It was reported that all-trans astaxanthin might exist as three stereoisomers, and the composition of all-trans stereoisomers in natural materials differs from that of synthetic products. However, the different biological effects of various all-trans stereoisomers still remain unclear. In the present study, we evaluated the bioactivity of three astaxanthin stereoisomers, (3S,3’S)-trans-, (3R,3’R)-trans-and meso-trans-astaxanthin, in regulating cell-mediated immune response using mice lymphocytes and peritoneal exudates cells (PECs) systems. After the treatment with three astaxanthin stereoisomers (20 μmol L−1), the lymphocyte proliferation capacity, neutral red phagocytosis of PECs and natural killer (NK) cell cytotoxic activity were comparatively assessed. The results showed that all three astaxanthin stereoisomers significantly promoted lymphocyte proliferation, phagocytic capacity of PECs, and cytotoxic activity of NK cells. Moreover, the (3S,3’S)-trans-astaxanthin exhibited a much higher response than others.

Determination of astaxanthin stereoisomers and colour attributes in flesh of rainbow trout (Oncorhynchus mykiss) as a tool to distinguish the dietary pigmentation source

The presence of carotenoids in animal tissue reflects their sources along the food chain. Astaxanthin, the main carotenoid used for salmonid pigmentation, is usually included in the feed as a synthetic product. However, other dietary sources of astaxanthin such as shrimp or krill wastes, algae meal or yeasts are also available on the market. Astaxanthin possesses two identical asymmetric atoms at C-3 and C-3′ making possible three optical isomers with all-trans configuration of the chain: 3S,3′S, 3R,3′S, and 3R,3′R. The distribution of the isomers in natural astaxanthin differs from that of the synthetic product. This latter is a racemic mixture, with a typical ratio of 1:2:1 (3S,3′S:3R,3′S:3R,3′R), while astaxanthin from natural sources has a variable distribution of the isomers deriving from the different biological organism that synthesized it. The high-performance liquid chromatographic (HPLC) analysis of all-trans isomers of astaxanthin was performed in different pigment sources, such as red yeast Phaffia rhodozyma, alga meal Haematococcus pluvialis, krill meal and oil, and shrimp meal. With the aim to investigate astaxanthin isomer ratios in flesh of fish fed different carotenoid sources, three groups of rainbow trout were fed for 60 days diets containing astaxanthin from synthetic source, H. pluvialis algae meal and P. rhodozyma red yeast. Moreover, the distribution of optical isomers of astaxanthin in trout purchased on the Italian market was investigated. A characteristic distribution of astaxanthin stereoisomers was detected for each pigment sources and such distribution was reproduced in the flesh of trout fed with that source. Colour values measured in different sites of fillet of rainbow trout fed with different pigment sources showed no significant differences. Similarly, different sources of pigment (natural or synthetic) produced colour values of fresh fillet with no relevant or significant differences. The coefficient of distance computed amongst the feed ingredient and the trout fillet astaxanthin stereoisomers was a useful tool to identify the origin of the pigment used on farm.

Reproducibility of the separation of astaxanthin stereoisomers on Pirkle covalent l-leucine and d-phenylglycine columns

The reproducibility of the separation of astaxanthin stereoisomers on columns packed with Pirkle covalent l-leucine chiral stationary phase (CSP) was examined by comparing six columns purchased from the same manufacturer. Differences were found even for columns packed with CSP from the same lot. The reproducibility of columns packed with Pirkle covalent d-phenylglycine CSP was also examined by comparing columns purchased from the same manufacturer as well as from different manufacturers. Significant differences were found for columns packed by different manufacturers. Chiral column-to-column reproducibility for complex stereoisomeric separations should therefore not be taken for granted.

Bioavailability of all- E-astaxanthin and Z-isomers of astaxanthin in rainbow trout ( Oncorhynchus mykiss)

Two cold-pelleted diets containing either 36.9 or 35.4 mg kg −1 of predominantly all- E-astaxanthin (97% of total astaxanthin) or a mixture of all- E- and Z-astaxanthin (64 and 36%, respectively), were fed to duplicate groups of rainbow trout ( Oncorhynchus mykiss) in freshwater (initial weight 0.4 kg) for 69 days. Average final weight was ca. 1.0 kg for both groups and the specific growth rate was 1.2–1.3% d −1. The all- E- and Z-isomer mixture of astaxanthin was produced from Carophyll Pink ® by an iodine-catalyzed isomerization. Flesh astaxanthin concentrations increased from 1.7 mg kg −1 in the initial sample to 6–7 mg kg −1 after 31 days. After 69 days, flesh carotenoid concentration of the trout fed all- E-astaxanthin tended to be higher than in trout fed the astaxanthin stereoisomer mixture (10.0 and 8.6 mg kg −1, respectively). At the end of the experiment, the trout fed all- E-astaxanthin had significantly redder (through the color tristimuli analysis CIE [1976], a ∗ tristimuli value) flesh than rainbow trout fed a mixture of all- E- and Z-astaxanthin. Apparent digestibility coefficients (ADC) of total astaxanthin were significantly higher in trout fed all- E-astaxanthin (79%) compared to trout fed the stereoisomer mixture (64%). No significant differences in the ADC of all- E-astaxanthin was observed between the two treatments, indicating a competitive mechanism of uptake of the different stereoisomers. ADC of all- E-astaxanthin was higher than that of 9 Z- and 13 Z-astaxanthin, and the ADC of 13 Z-astaxanthin was significantly higher than that for 9 Z-astaxanthin. This indicates that the Z-astaxanthin isomers are not utilized to the same extent as all- E-astaxanthin for flesh pigmentation. No significant differences were observed in total astaxanthin retention in the flesh. However, the retention of all- E-astaxanthin was higher in trout fed the stereoisomer mixture of astaxanthin than in the group fed all- E-astaxanthin. The better utilization of digestible carotenoids in the trout fed a mixture of all- E- and Z-astaxanthin isomers did not fully compensate for the low digestibility of astaxanthin in this group. No differences in astaxanthin stereoisomer composition in the flesh were observed between treatments. This indicates a selectivity in metabolism of the different stereoisomers of astaxanthin, either during absorption, transport or deposition, or their combinations and suggests that substantial isomerization of astaxanthin Z-isomers occurs in the liver. The retention of dietary astaxanthin in the flesh was as high as 24–32%. No significant differences in ADC were observed for dry matter, protein, fat or energy, while ADC for ash was significantly higher for the group fed the diet containing all- E-astaxanthin. The tendency for higher retention of digestible total astaxanthin in the flesh of trout fed a stereoisomer mixture of astaxanthin suggests that the stereoisomer composition of the dietary astaxanthin may influence the absorption capacity and bioavailability of total astaxanthin, probably by increasing intestinal micellar load of total astaxanthin.

Chromatographic Analysis of Synthesized Astaxanthin—A Handy Tool for the Ecologist and the Forensic Chemist?

Abstract Detection of canthaxanthin or of an astaxanthin stereoisomer composition deviating from that in wild salmonids seems to be a reliable method of distinguishing farmed from wild salmonids. This is especially true when a high amount of the (3R, 3'S) stereoisomer of astaxanthin is present. A 1:2:1 distribution of (3S,3'S), (3R,3'S), and (3R,3'S) isomers (“racemic astaxanthin”) is not a fundamental property of the astaxanthin synthesized for fish feeds; virtually any ratio of the astaxanthin stereoisomers may be manufactured by modern techniques. The stereoisomer com-position of astaxanthin from decapod wastes often resembles that of racemic astaxanthin. It is argued that no known chromatographical method today is in itself able to detect any synthesized carotenoid per se. This is important in view of the trend to include untraditional astaxanthin sources in fish feeds, which may eventually make the stereoisomeric ratio most frequently found in farmed salmonids today more differentiated in the future....

Comparative biochemical studies of carotenoids in fish. XXXIV. The occurrence of eight stereoisomers of tunaxanthin from the fresh-water fish Siniperca scherzeri.

The carotenoids in the integuments of Siniperca scherzeri (Kouraiketsugyo in Japanese) which belongs to the division percichthyes and is a native fresh-water fish of the Republic of Korea were investigated. Tunaxanthin believed to be a characteristic carotenoid of marine fish was a major carotenoid (35.1% of the total carotenoid) and consisted of eight stereoisomers i.e. tunaxanthin A, B, C, D, E, G, H, and I. Therefore, the assumption that tunaxanthin might be a chemical indicator in the division percichthyes has been proved by the present investigation. Lutein F was first isolated in fresh-water fish. (6R, 6'R)-, (6R, 6'S: meso)-, and (6S, 6'S)-ε, ε-carotene-3, 3'-dione as a key intermediate in reductive metabolic pathway of astaxanthin to tunaxanthin in fish were isolated along with (3R, 3'R)-, (3R, 3'S: meso)- and (3S, 3'S)-zeaxanthin, and (3R, 3'R)-, (3R, 3'S: meso)-, and (3S, 3'S)-astaxanthin. Accordingly, the presence of the reductive metabolic pathways of three stereoisomers of astaxanthin into tunaxanthin A, B, C, D, E, G, H, and I via three stereoisomers of zeaxanthin, and three stereoisomers of ε, ε-carotene-3, 3'-dione has been demonstrated in S. scherzeri.

Comparative biochemical studies of carotenoids in nine species of cephalopoda

1. The carotenoids of nine species of Cephalopoda were investigated from a comparative biochemical point of view. Carotenoids were obtained from six species, but no carotenoid from any other species. 2. Three stereoisomers of astaxanthin were found to be major components, accompanied by small amounts of β,β-caroten, (3S,3′S)-7,8-didehydro-astaxanthin and (3S,3′S)-7,8,7′,8′-tetradehydro-astaxanthin. 3. Carotenoid patterns of Cephalopoda were quite different from those of both Gastropoda and Bivalvia, and were very similar to those of Crustacea.

Carotenoids of crustacea. VI. The carotenoids of crab Paralithodes brevipes (Hanasakigani in Japanese).

The carotenoids in the carapace, flesh and gonad of Paralithodes brevipes were investigated from the stereochemical point of view. The absolute configuration of papilioerythrinone (=3-hydroxy-β, e-carotene-4, 3'-dione) isolated from the crab was determined to be (3S, 6'R)-configuration. In the carapace and flesh, three stereoisomers of astaxanthin (33-39%) and (3S, 3'S)-7, 8-didehydro-astaxanthin (27-32%) were identified as major components accompanied by (3S, 3'S)-7, 8, 7', 8'-tetradehydro-astaxanthin (6-7%), fritschiellaxanthin (4-10%) and papilioerythrinone (2-6%) etc., while in the gonad β, β-carotene (64%) was found to be dominant along with three stereo-isomers of astaxanthin (11%), echinenone (7%) and isocryptoxanthin (3%) etc. From the experimental results obtained, we proposed the plausible oxidative metabolic path-way of lutein A to papilioerythrinone via fritschiellaxanthin in P. brevipes.

Metabolism of three stereoisomers of astaxanthin in the fish, rainbow trout and tilapia

1. 1. In rainbow trout ( Salmo gairdneri), the dietary astaxanthin diesters were mostly absorbed and accumulated in their integuments keeping their configurations, and partially metabolized to (3R,3′R)-zeaxanthin (major) and/or (3R,3′S)-zeaxanthin (medium) and/or (3S,3′S)-zeaxanthin (minor). 2. 2. In tilapia ( Tilapia nilotica), the three stereoisomers of astaxanthin diesters were promptly metabolized to only (3S,3′S)-astaxanthin, and subsequently to (3R,3′R)-zeaxanthin and/or (3R,3′S)-zeaxanthin and/or (3S,3′S)-zeaxanthin at an invariable ratio, 4:1:0.3. 3. 3. The above facts indicate that the conversion from 3S- to 3R-configuration was carried out in vivo, and vice versa, and that astaxanthins were reductively metabolized to zeaxanthins in both the fish.