Astaxanthin Content Research Articles

Metabolomics of astaxanthin biosynthesis and corresponding regulation strategies in Phaffia rhodozyma.

Astaxanthin is a valuable carotenoid and is used as antioxidant and health care. Phaffia rhodozyma is a potential strain for the biosynthesis of astaxanthin. The unclear metabolic characteristics of P. rhodozyma at different metabolic stages hinder astaxanthin's promotion. This study is conducted to investigate metabolite changes based on quadrupole time-of-flight mass spectrometry metabolomics method. The results showed that the downregulation of purine, pyrimidine, amino acid synthesis, and glycolytic pathways contributed to astaxanthin biosynthesis. Meanwhile, the upregulation of lipid metabolites contributed to astaxanthin accumulation. Therefore, the regulation strategies were proposed based on this. The addition of sodium orthovanadate inhibited the amino acid pathway to increase astaxanthin concentration by 19.2%. And the addition of melatonin promoted lipid metabolism to increase the astaxanthin concentration by 30.3%. It further confirmed that inhibition of amino acid metabolism and promotion of lipid metabolism were beneficial for astaxanthin biosynthesis of P. rhodozyma. It is helpful in understanding metabolic pathways affecting astaxanthin of P. rhodozyma and provides regulatory strategies for metabolism.

Suitable natural astaxanthin supplementation with Haematococcus pluvialis improves the physiological function and stress response to air exposure of juvenile red swamp crayfish (Procambarus clarkii)

High mortality during transportation has restricted industrial development of red swamp crayfish (Procambarus clarkii), especially juveniles, in China. Supplementation with Haematococcus pluvialis has been proved to promote crustacean survival and growth. Therefore, this study investigated the effects of dietary natural astaxanthin derived from H. pluvialis on the growth performance, pigmentation, digestion, antioxidant capacity, immunity, and response to air exposure stress of juvenile red swamp crayfish. Five isonitrogenous and isolipidic diets were formulated containing a graded H. pluvialis powder inclusion (0, 0.15, 0.30, 0.45 and 0.60%) level. The results indicated that dietary astaxanthin significantly improved the survival rate and weight gain rate of juvenile crayfish (P < 0.05). As dietary astaxanthin levels increased, a* values in the carapace, muscle, and ovaries improved and the carotenoid content significantly increased (P < 0.05). Lipase (LPS), and cellulase (CL) activities in the hepatopancreas and intestines, and α-amylase, and pepsin (PEP) activities in the hepatopancreas, significantly increased and then decreased with increasing dietary astaxanthin levels (P < 0.05). Dietary astaxanthin significantly decreased the malondialdehyde (MDA) content in the hemolymph (P < 0.05). Total superoxide dismutase (T-SOD), total antioxidant capacity and acid phosphatase (ACP) activities in the hepatopancreas and hemolymph, as well as alkaline phosphatase in the hepatopancreas, followed a similar pattern as the digestive enzymes (P < 0.05). Furthermore, dietary astaxanthin significantly improved succinate dehydrogenase (SDH) activity in the hepatopancreas and muscle after a 24-h air exposure stress test, while decreasing the MDA and lactic acid content (LD) in muscle (P < 0.05). Based on the quadratic regression analysis of LPS, PEP, CL, T-SOD, ACP and SDH in hepatopancreas, and MDA and LD in muscle, the optimal dietary natural astaxanthin content for juvenile red swamp crayfish ranges from 63.55 to 84.40 mg kg−1.

Cytochrome P450-mediated co-metabolism of fluoroquinolones by Haematococcus lacustris for simultaneously promoting astaxanthin and lipid accumulation

Microalgae-based antibiotic removal treatment has attracted attention because of its low carbon and sustainable advantages. The microalgal co-metabolism system with a suitable carbon source leads to enhanced performance of pollutant removal. However, currently, limited knowledge is available for the removal of fluoroquinolone using a microalgae-mediated co-metabolism system. In this study, we first investigated that the biotic processes by alga Haematococcus lacustris in the co-metabolism system by adding glycerol would be the main contributors responsible for the removal of 10 mg/L ofloxacin (OFL) with the efficiency of 79.73% and the removal of 10 mg/L enrofloxacin (ENR) with the efficiency of 54.10%, respectively. Furthermore, we found that pyruvate from glycerol was converted into substrates and precursors, thereby resulting in the significant accumulations of microalgal astaxanthin and lipid. The astaxanthin content of H. lacustris was achieved at 4.81% and 4.69% treated with OFL and ENR in the presence of glycerol, with 16.04% and 14.55% of lipid content, respectively. The proposed metabolites and pathways were identified to plausibly explain the biodegradation of fluoroquinolone by H. lacustris. The molecular analyses demonstrated that cytochrome P450 (CYP450) enzymes are responsible for the biodegradation of fluoroquinolone, and it was further verified that fluoroquinolones might insert into CYP450 to finally form an efficient and tight binding conformation by molecular dynamic simulation. These findings provide a microalgae-based route for feasible and sustainable biodegradation of antibiotics using a co-metabolism strategy comprising glycerol as a carbon source, with the synergistic accumulation of valuable products.

‘Biotic’ potential of the red yeast Rhodotorula mucilaginosa strain JM-01 on the growth, shell pigmentation, and immune defense attributes of the shrimp, Penaeus vannamei

A 6-week feeding trial was conducted to evaluate the effects of dietary supplementation of Rhodotorula mucilaginosa JM-01 in different forms (i.e. LC, live cells; FS, fermentation supernatant; CLS, compound of live cells with fermentation supernatant; SKE, sonication-killed cell-free extracts; HK, heat-killed cells; control, basal diet without R. mucilaginosa) on the growth performance, shell pigmentation, immune responses, and disease resistance of the shrimp Penaeus vannamei. The results indicated that the final weight and specific growth rate of shrimp were significantly improved and the feed conversion ratio was significantly reduced in the CLS and HK groups compared to the control. The redness and yellowness of the ventral body color and shell astaxanthin contents in the LC, CLS, SKE, and HK groups were significantly elevated relative to the control, while the lightness was significantly reduced. The challenge test to Vibrio parahaemolyticus demonstrated that the cumulative mortality was significantly lower than the control in all experimental groups. Compared to the control, acid phosphatase, alkaline phosphatase, total superoxide dismutase, lysozyme, total nitric oxide synthase, and catalase activities and total antioxidant capacity and phenoloxidase contents in the serum of shrimp were significantly higher in all experimental groups except the FS group. The relative expression levels of the proPO, SOD, CAT, LZM, Imd, Toll, Relish, TOR, 4E-BP, elF4E1α and elF4E2 genes in the shrimp intestine were significantly enhanced in the LC, CLS, SKE, and HK groups, but only partially induced in the FS group. When the growth performance, body color, astaxanthin contents, and immune responses of shrimp were considered collectively, the compound of live cells with fermentation supernatant exhibited the greatest beneficial effect. However, the postbiotics, i.e. heat-killed cells or sonication-killed cell-free extracts, would be more suited than probiotics in shrimp farming practice, considering the shell-life for storage and the convenience for transportation.

Extraction of bioactive lipids from Pleuroncodes monodon using organic solvents and supercritical CO2

A huge volume of Engraulis ringens (Peruvian anchoveta) is caught together with the species Pleuroncodes monodon (munida), whose potential bioactive lipids are not commercially exploited. In the present study, lipid with carotenoid pigment (astaxanthin) and essential fatty acids (EPA+DHA) were obtained from munida lipids extracted with hexane:isopropyl alcohol (He-I), acetone (Ac), ethanol (Et) and supercritical CO2 + ethanol (SC-CO2-Et). The functional quality of the fatty acids was determined by atherogenicity index (AI), thrombogenicity index (TI) and the hypocholesterolemia:hypercholesterolemia (H:H) ratio. The highest astaxanthin (ASTX) contents (4238.65 and 4086.71 µg/g lipid) corresponded to extractions using Ac and SC-CO2-Et. EPA+DHA ranged from 31.15 to 31.85% and the functional quality ranges were between 0.56-0.61 (AI), 0.19-0.21 (TI) and 1.73-1.81 (H:H). Consequently, SC-CO2-Et extraction would be advisable because of its low environmental impact. The IA and IT quality indexes suggest that the consumption of munida lipids would be healthy, although the H:H ratio shows the opposite.

Expression of fatty acid related gene promotes astaxanthin heterologous production in Chlamydomonas reinhardtii.

Natural astaxanthin is a high-value ketone carotenoid mainly derived from Haematococcus pluvialis, which is an excellent antioxidant for human consumption. To study the role of lipids in accumulation of astaxanthin, the H. pluvialis-derived astaxanthin synthesis pathway genes (β-carotene ketolase gene, BKT and β-carotene hydroxylase gene, BCH) and fatty acid elongation gene (mitochondrial trans-2-enoyl-coa reductase gene, MECR) were heterologously co-expressed in C. reinhardtii. Zeaxanthin, the precursor of astaxanthin synthesis, was significantly increased after BKT and BCH were expressed. In contrast, the α-carotene that competes with astaxanthin synthesis for lycopene decreased significantly. This redistribution of carbon flow was conducive to the synthesis of astaxanthin. In addition, the transformant only expressed astaxanthin metabolism related genes (BKT, BCH) would lead to an increase in total lipid, a decrease in monounsaturated fatty acids and an increase in polyunsaturated fatty acids. On this basis, the expression of MECR gene further increased the total lipid, and the relative content of different fatty acids also changed. The astaxanthin content of algal strains transformed with BKT and BCH genes was nearly 50% higher than that of the wild type. On this basis, the astaxanthin content of transformants expressing MECR gene related to long-chain fatty acid synthesis was increased by 227.5%. In this study, an astaxanthin production model similar to H. pluvialis by combining carotenoid metabolism and fatty acid metabolism was constructed in C. reinhardtii. The results suggest that the increase in astaxanthin is indeed linked to the regulation of fatty acid metabolism, and this link may involve the type of fatty acids and the dynamics of astaxanthin ester in cells. The strategy of promoting the synthesis of fatty acids has potential to achieve efficient production of astaxanthin in C. reinhardtii.

Effect of astaxanthin isomer supplementation on their accumulation in edible orthopterans: migratory locusts and two-spotted crickets

The effects of an all-E-isomer-rich astaxanthin diet (E-AST-D) andZ-isomer-rich astaxanthin diet (Z-AST-D) supplementation on astaxanthin accumulation and isomer composition in the edible orthopterans, migratory locust (Locusta migratoria) and two-spotted cricket (Gryllus bimaculatus), were investigated.Z-Isomer-rich astaxanthin was prepared from the all-E-isomer via thermal treatment in corn oil at 160 °C for 30 min, increasing the totalZ-isomer ratio from 1.3 to 57.7%. Supplementation with E-AST-D and Z-AST-D toL. migratoria had little effects on astaxanthin concentration and isomer composition in the body. In contrast, astaxanthin supplementation toG. bimaculatus significantly improved the astaxanthin concentration, and when Z-AST-D was fed, the astaxanthin concentration was approximately eight times higher than that of supplementation with E-AST-D. This suggests thatL. migratoria exhibits very low astaxanthin isomer bioavailability, whereasG. bimaculatus can absorb astaxanthin isomers from its diet.L. migratoria may synthesise astaxanthin endogenously regardless of dietary astaxanthin content. TheZ-isomers were more bioavailable than the all-E-isomer inG. bimaculatus. Furthermore, astaxanthin isomer ratios in the faeces of both species were different from the dietary sources, suggesting that these ratios were modulated during digestion. These findings are important for increasing the added value of insect foods and for elucidating the mechanism of astaxanthin isomerisation in insects.

The protective effects of astaxanthin on pre-antral follicle degeneration in ovine vitrified/warmed ovarian tissue

This study assesses the protective effects of astaxanthin (AST) against vitrification/warming-induced cryoinjuries of ovarian tissue slices in sheep. Cortical slices of slaughterhouse acquired-ovine ovaries were randomly distributed in different groups: fresh, toxicity, and five vitrification groups including vitrification in presence of 0 (control group), 1, 10 and 100 μM astaxanthin or 100 μM vitamin E. After vitrification/warming and 24 h culturing, the samples were subjected to histological studies, antioxidant evaluation by TAC and TBAR assays, and assessment of relative expression of BMP4, BMP15, GDF9 and KITLG genes related to folliculogenesis and follicular growth regulation. According to the results, vitrification reduced the percentage of morphologically intact follicles compared to the fresh and toxicity groups (p < 0.05). In vitrification groups, vitamin E and all three concentrations of AST increased the percentage of intact pre-antral follicles and antioxidant activity relative to the vitrified control (p < 0.05). This enhancement significantly occurred in 10 μM AST group more than vitamin E (p < 0.05). Also, 10 μM concentration of AST enhanced the expression of all the examined genes compared to the control (p < 0.05), while the expression of BMP4, BMP15 and KITLG was higher in the AST than vitamin E (p < 0.05). The latter could increase only the expression of GDF9 compared to the control group (p = 0.011). In conclusion, AST is a highly effective antioxidant for maintaining the survival of pre-antral follicles, retaining cell density, increasing total antioxidant capacity, and increasing the expression of some genes related to follicular development after short-term culture of vitrified/warmed ovarian tissue slices.

Dietary Level of the Omega-3 Fatty Acids EPA and DHA Influence the Flesh Pigmentation in Atlantic Salmon.

Atlantic salmon with a start weight of 53 g were fed diets with different levels of EPA and DHA or a diet with 1 : 1 EPA+DHA (0%, 1.0%, and 2.0% of the diet). At 400 g, all fish groups were mixed and equally distributed in new tanks and fed three diets with 0.2%, 1.0%, or 1.7% of EPA+DHA. At 1200 g, the fish were transferred to seawater pens where they were fed the same three diets until they reached a slaughter size of 3.5 kg. The fillet concentration of astaxanthin and its metabolite idoxanthin was analysed before transfer to seawater pens at 1200 g and at slaughter. The fatty acid composition in the fillet was also analysed at the same time points. Salmon fed low levels of EPA and DHA had lower fillet astaxanthin concentration and higher metabolic conversion of astaxanthin to idoxanthin compared to salmon fed higher dietary levels of EPA and/or DHA. DHA had a more positive effect on fillet astaxanthin concentrations than EPA. There were positive correlations between fillet DHA, EPA, sum N-3 fatty acids, and fillet astaxanthin concentration. A negative correlation was found between the concentration of N-6 fatty acids in the fillet and the astaxanthin concentration.

Fermentative production of astaxanthin from sorghum distillery residue by an indigenous Aurantiochytrium sp. CJ6 strain using a continuous-feeding fed-batch process

In this study, Aurantiochytrium sp. CJ6 was cultivated heterotrophically on a waste resource, sorghum distillery residue (SDR) hydrolysate without adding any nitrogen sources. Mild sulfuric acid treatment released sugars that supported the growth of CJ6. Optimal operating parameters (salinity, 2.5%; pH, 7.5; with light exposure) determined using batch cultivation attained biomass concentration and astaxanthin content of 3.72 g/L and 69.32 µg/g dry cell weight (DCW), respectively. Using continuous-feeding fed-batch (CF-FB) fermentation, the biomass concentration of CJ6 increased to 6.3 g/L with biomass productivity and sugar utilization rate of 0.286 mg/L/d and 1.26 g/L/d, respectively. Meanwhile, CJ6 obtained maximum astaxanthin content (93.9 µg/g DCW) and astaxanthin concentration (0.565 mg/L) after 20-day cultivation. Thus, the CF-FB fermentation strategy seems to have a high potential for the cultivation of thraustochytrids to produce the high-value product (astaxanthin) using SDR as the feedstock to achieve circular economy.

Transcriptomics analysis and fed-batch regulation of high astaxanthin producing Phaffia rhodozyma/Xanthophyllomyces dendrorhous obtained through adaptive laboratory evolution.

Astaxanthin has high utilization value in functional food because of its strong antioxidant capacity. However, the astaxanthin content of Phaffia rhodozyma is relatively low. Adaptive laboratory evolution is an excellent method to obtain high-yield strains. TiO2 is a good inducer of oxidative stress. In this study, different concentrations of TiO2 were used to domesticate P. rhodozyma. Results showed that the optimal astaxanthin-producing P. rhodozyma JMU-ALE105 was obtained under domestication with 1000mg/L TiO2 concentration on the 105th day. After fermentation, the astaxanthin content reached 6.50mg/g, which was 41.61% higher than that of the original strain. The ALE105 strain was fermented by batch and fed-batch, and the astaxanthin content reached 6.81mg/g. Transcriptomics analysis showed that astaxanthin synthesis pathway, fatty acid, pyruvate and nitrogen metabolism pathway of ALE105 strain were significantly up-regulated. Based on the nitrogen metabolism pathway, the nitrogen source was adjusted by ammonium sulphate fed-batch fermentation, which increased the astaxanthin content reached 8.36mg/g. This study provides technical basis and theoretical research for promoting industrialization of astaxanthin production of P. rhodozyma.

Bioactive Compounds of Shrimp Shell Waste from Palaemon serratus and Palaemon varians from Portuguese Coast

The production and consumption of shrimp species create massive amounts of shrimp bio-waste. In this study, shrimp shell waste from Palaemon serratus and Palaemon varians from the Portuguese coast was characterized. Regarding the antioxidant capacity, the obtained values were between 4.7 and 10.4 mg gallic acid equivalents (GAE)/g dry weight (dw) for Total phenolic content (TPC); 3 and 7 mg ascorbic acid equivalents (AAE)/g dw for Ferric reducing antioxidant power assay (FRAP); 0.4 and 1.2 mg Trolox equivalent (TE)/g dw for 2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical scavenging (DPPH•); 4 and 11 mg TE/g dw for 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity (ABTS•+); and 72 and 130 mg TE/g dw for Oxygen radical absorbance capacity (ORAC). For the antimicrobial activity, shrimp shell waste from P. varians formed inhibition zones between 14 and 23 mm. Total carotenoid content values were in the range of 28 and 134 μg/g dw, and according to their HPLC-PAD profile, β-carotene and astaxanthin contents were between 0.3 and 7.6 μg/g dw and 1.1 and 26.1 μg/g dw, respectively. These studies are critical to recognizing the potential added value of shrimp shell waste as possible colorants and preservatives with antioxidant protection capacity to be used in the food industry.

Pulsed Electric Fields (PEF) and Accelerated Solvent Extraction (ASE) for Valorization of Red (Aristeus antennatus) and Camarote (Melicertus kerathurus) Shrimp Side Streams: Antioxidant and HPLC Evaluation of the Carotenoid Astaxanthin Recovery.

Shrimp side streams represent an important natural source of astaxanthin. Optimization of the astaxanthin extraction process from shrimp side streams is of great importance for the valorization of crustacean side streams and the development of astaxanthin-related products. The combined and independent effects of two innovative extraction technologies (pulsed electric fields (PEFs) and accelerated solvent extraction (ASE)) alone and/or combined in a sequential step, using two different solvents on astaxanthin extraction from two shrimp species, were evaluated. Astaxanthin content in the extracts of shrimp side streams was determined by both spectrophotometric and HPLC assays, being the determination of the carotenoid profiles performed by HPLC analysis. Compared to a solvent extraction control procedure, the astaxanthin content was increased after ASE and PEF treatments, for both shrimp species, independently of the solvent used. The highest recovery (585.90 µg/g) was obtained for the species A. antennatus, with the solvent DMSO when PEF and ASE were combined, while the increase in antioxidant capacity varied depending on the solvent used. HPLC analysis of the samples revealed the presence of unesterified (all-E) astaxanthin, four unesterified Z isomers of astaxanthin and many unresolved astaxanthin esters. Both technologies are useful tools to recover antioxidant valuable carotenoids such as astaxanthin from shrimp side streams.

Optimization of cell wall breaking process of the microalgae Haematococcus pluvialis.

Haematococcus pluvialis can synthesize and accumulate astaxanthin, and is regarded as the organism with the highest content of astaxanthin in the current nature. However, only when Haematococcus pluvialis cell wall is broken can the astaxanthin be effectively extracted. Therefore, the breaking of the hard cell wall of Haematococcus pluvialis becomes the key difficulty hindering the extraction of astaxanthin. In this study, the cell wall was broken using enzyme digestion and mechanical action and the response surface methodology was used to optimize the cell wall breaking process. Taking the cell wall breaking rate of Haematococcus pluvialis as the index, the single factor experiment was used to calculate the effects of solid-liquid ratio, enzyme type and dosage, digestion temperature, digestion pH and hydrolysis time on the cell wall breaking rate. When the ultrasonic power is 175 W and the ultrasonic time is 2 min, the highest wall breaking rate is 68.8%. The high pass tissue grinder has the best wall breaking efficiency of 70.3% in 6 min and 70 Hz. In combination with single factor analysis and response surface analysis, the optimum enzyme digestion conditions were determined as follows: the ratio of material to liquid was 1:150, the amount of enzyme was 1%, the ratio of Pectinase to cellulase was 1:1, and the optimum hydrolysis conditions were as follows: hydrolysis time 5 h, hydrolysis temperature 55 °C, pH 5.5; and the amount of enzyme was 1%. The theoretical wall breaking rate is 77.2%, the actual extraction rate is 75.4%, and the relative error is 2.2%. In conclusion, the method of using combined enzyme to break the wall of Haematococcus pluvialis is simple, mild, green and efficient. It can be used in the processing of broken wall.

Enhanced astaxanthin production of Haematococcus pluvialis strains induced salt and high light resistance with gamma irradiation

This study was conducted to increase the productivity of biomass that contains high astaxanthin content by developing a mutant Haematococcus pluvialis strain with strong environmental tolerance. H. pluvialis has a low cell-growth rate and is vulnerable to stressors such as salinity or light intensity, which may hinder large-scale commercial cultivation. A mutant M5 strain selected through 5000-Gy gamma irradiation showed improved biomass and astaxanthin production under high-salinity and high-light intensity conditions. With enhanced SOD activity and overexpressed astaxanthin biosynthesis genes (lyc, crtR-b, bkt2), M5 demonstrated an increase in biomass and astaxanthin productivity by 86.70 % and 66.15 %, respectively compared to those of untreated cells. Also, the omega-3 content of M5 increased by 149.44 % under 40 mM CaCl2 compared to the untreated cells. Finally, even when subjected to high-intensity light irradiation for the whole life cycle, the biomass and astaxanthin concentration increased by 84.99 % and 241 %, respectively, compared to the wild-type cells.

A novel stepwise dilution strategy to improve astaxanthin production of Haematococcus pluvialis in outdoor horizontal tubular photobioreactors

The volume average light intensity in the photobioreactor (PBR) used for astaxanthin accumulation of Haematococcus pluvialis gradually decreased due to light attenuation caused by the accumulated biomass and astaxanthin. Excessive light intensity in the early stage of photoinduction resulted in photoinhibition while insufficient light intensity in the late stage limited the astaxanthin accumulation. In this study, the effect of dry cell weight on astaxanthin production was first investigated and the astaxanthin accumulation was improved by dilution. Based on this, a stepwise dilution strategy in the horizontal tubular photobioreactor (HTPBR) was developed to promote astaxanthin production and afterward verified in outdoor 16.5 m3 HTPBRs with 5-row parallel tubes. It was proved that twice diluting with an initial dry cell weight of 1 g L−1 in 3-row parallel tubes was the optima. By the stepwise dilution strategy, the astaxanthin content in algal cells and the astaxanthin productivity per dry heterotrophic cell weight increased from 2.56 % to 3.40 % and from 41.0 mg g−1 to 55.0 mg g−1, respectively. The gross profit was improved by 51.32 % by the easily operated stepwise dilution strategy.

Co-encapsulated astaxanthin and kaempferol nanoparticles: fabrication, characterization, and their potential synergistic effects on treating non-alcoholic fatty liver disease.

Astaxanthin and kaempferol, renowned natural compounds, possess potent antioxidant properties and exhibit remarkable biological activities. However, their poor water solubility, low stability, and limited bioavailability are the primary bottlenecks that restrict their utilization in pharmaceuticals and functional foods. To overcome these drawbacks, this study aims to fabricate astaxanthin/kaempferol co-encapsulated nanoparticles and investigate their synergistic effects on reducing the risk of stress oxidation, chronic inflammation, and lipid accumulation in RAW264.7 and HepG2 cells. The synthesized astaxanthin/kaempferol nanoparticles exhibited well-defined spherical morphology with an average particle diameter ranging from 74 to 120 nm. These nanoparticles demonstrated excellent stability with the remaining astaxanthin content ranging from 82.5% to 92.1% after 6 months of storage at 4 °C. Nanoastaxanthin/kaempferol displayed high dispersibility and stability in aqueous solutions, resulting in a significant enhancement of their bioactivity. In vitro assessments on cell lines revealed that nanoastaxanthin/kaempferol enhanced the inhibition of H2O2-induced oxidative stress in HepG2 and LPS-induced NO production in RAW264.7 compared to nanoastaxanthin. Additionally, these nanoparticles reduced the expression of genes involved in inflammation (iNOS, IL-6 and TNF-α). Moreover, hepatocytes treated with nanoastaxanthin/kaempferol showed a reduction in lipid content compared to those treated with nanoastaxanthin, through enhanced regulation of lipid metabolism-related genes. Overall, these findings suggest that the successful fabrication of co-encapsulated nanoparticles containing astaxanthin and kaempferol holds promising therapeutic potential in the treatment of non-alcoholic fatty liver disease.

Astaxanthin-loaded nanoparticles enhance its cell uptake, antioxidant and hypolipidemic activities in multiple cell lines

Astaxanthin is a natural carotenoid pigment, which provides many benefits to human health and nutrition. However, the human body has a low bioavailability of astaxanthin due to its poor solubility in the water phase. This study aimed to prepare astaxanthin nanoparticles using an emulsification/solvent evaporation method and then to evaluate bioavailability of nano-astaxanthin for biomedical applications. The results showed that the combinative use of cremophor RH40 as surfactants and polyethylene glycol–polylactic acid copolymer as an encapsulation agent generated well-defined astaxanthin nanoparticles with 5% astaxanthin content. These nanoparticles exhibited spherical morphology with average particle diameters of 90 nm. Nanoastaxanthin had high DPPH free radical scavenging activity and significantly improved cell uptake compared to the free astaxanthin. Astaxanthin nanoparticles showed no cytotoxicity against HT29, HepG2 and RAW264.7 cells up to a concentration of 500 μg/mL and event showed a more powerful cytoprotective effect on H2O2-induced oxidative HepG2 cell damage at concentrations of 50 and 100 μg/mL. Besides that, the activity of antioxidant enzymes (catalase and glutathione peroxidase) and gene expressions of Nrf2, HO-1 and NQO1 increased concentration-dependently, while the mRNA level of Keap1 significantly decreased in cells incubated with nanoastaxanthin compared to astaxanthin and control groups. Moreover, hepatocytes and murine RAW264.7 macrophages treated with nanoastaxanthin, but not with free astaxanthin, displayed to reduce cellular lipid accumulation compared with control cells via altering the expression of key genes in lipid metabolism (LDLR, CYP7A1, FAS, PPARα, CPT-1 and LXRα in HepG2 cells and ABCA1 and G1 in RAW264.7 cells). Our results highlight the great potential of nanoastaxanthin for applications in human health and nutrition.

Effects of Blanching and Drying Condition on the Quality of Small Shrimp (Acetes)

The study aimed to evaluate the influence of various parameters of the blanching and drying condition of small shrimp (Acetes) on some product quality parameters. Some criteria were assessed, such as salt content, astaxanthin content (ATC), and color of small shrimp. The results showed that the blanching time significantly affected the salt content. When increasing the blanching time, the salt content was found to increase from 17.35 ± 2.48 mg/g DW to 39.51 ± 0.45 mg/g DW. The astaxanthin content achieved the highest value (0.026 ± 0.001 mg/g DW) in a 2% salt solution. The study showed that the blanching and drying processes significantly affected the salt content, astaxanthin, and color of the small shrimp, and the optimized temperatures for blanching and drying were 70°C and 60°C, respectively.

Cryptochrome-mediated blue-light signal contributes to carotenoids biosynthesis in microalgae.

Microalgae are considered as ideal cell factories for producing natural carotenoids which display favorable biological activities. As the most important abiotic factor, light not only provides energy for photosynthetic metabolism, but also regulates numerous biological processes. Blue light is the main wavelength of light that can travel through water. Previous studies have shown that blue light triggered carotenoid accumulation in several microalgae species, but the molecular mechanism remains unclear. Cryptochromes were blue-light-absorbing photoreceptors that have been found in all studied algal genomes. In this study, several different types of cryptochrome genes were cloned from Haematococcus pluvialis and Phaeodactylum tricornutum. Among them, cryptochrome genes HpCRY4 from H. pluvialis and PtCPF1 from P. tricornutum were upregulated under blue light treatment, in correlation with the increase of astaxanthin and fucoxanthin contents. Besides, heterologous expression and gene knockout was performed to verify the function of HpCRY4 and PtCPF1 in regulating carotenoid biosynthesis in microalgae. These results indicate that carotenoid biosynthesis in microalgae promoted by blue light was mediated by cryptochromes as photoreceptors.