A comprehensive study of the colloidal properties, biocompatibility, and synergistic antioxidant actions of Antarctic krill phospholipids.

Excipient selection is crucial to address the oxidation and solubility challenges of bioactive substances, impacting their safety and efficacy. AKPL, a novel ω-3 polyunsaturated fatty acids (PUFAs) esterified phospholipid derived from Antarctic krill, demonstrates unique antioxidant capabilities and synergistic effects. It exhibits pronounced surface activity and electronegativity at physiological pH, as evidenced by a critical micelle concentration (CMC) of 0.15 g/L and ζ-potential of -49.9 mV. In aqueous environments, AKPL self-assembles into liposomal structures, offering high biocompatibility and promoting cell proliferation. Its polyunsaturated bond-rich structure provides additional oxidation sites, imparting antioxidant properties superior to other phospholipids like DSPC and DOPC. Additionally, AKPL augments the efficacy of lipophilic antioxidants, such as alpha-tocopherol and curcumin, in aqueous media through both intermolecular and intramolecular interactions. In sum, AKPL emerges as an innovative unsaturated phospholipid, offering new strategies for encapsulating and delivering oxygen-sensitive agents.

Krill oil treatment ameliorates lipid metabolism imbalance in chronic unpredicted mild stress-induced depression-like behavior in mice.

The pathology of depression involves various factors including the interaction between genes and the environment. The deficiency of n-3 polyunsaturated fatty acids (n-3 PUFAs) in the brain and depressive symptoms are closely related. Krill oil contains abundant amounts of n-3 PUFAs incorporated in phosphatidylcholine. However, the effect of krill oil treatment on depression-like behaviors induced by chronic stress and its molecular mechanism in the brain remain poorly understood. Here, we used a chronic unpredictable mild stress (CUMS) model to evaluate the effect of krill oil on depression-like behaviors and explored its molecular mechanism through lipid metabolomics and mRNA profiles in the whole brain. We observed that CUMS-induced depression-like behaviors were ameliorated by krill oil supplementation in mice. The metabolism of glycerophospholipids and sphingolipids was disrupted by CUMS treatment, which were ameliorated after krill oil supplementation. Further analysis found that differently expressed genes after krill oil supplementation were mainly enriched in the membrane structures and neuroactive ligand-receptor interaction pathway, which may be responsible for the amelioration of CUMS-induced depression-like behaviors. Altogether, our results uncovered the relationship between lipid metabolism and CUMS, and provided new strategies for the prevention and treatment of depression.

Administration of krill oil extends lifespan of fish Nothobranchius guentheri via enhancement of antioxidant system and suppression of NF-κB pathway.

Krill oil (KO) extracted from Antarctic krill (Euphausia superba) mainly comprises phospholipids and triglycerides. KO has been shown to prolong the median lifespan of the nematode Caenorhabditis elegans, but to shorten the lifespan of long-lived F1 mice; therefore, it remains controversial over the life-extending property of KO. In this study, we clearly demonstrated that dietary intake of KO extended both the mean and maximum lifespans of aged male Nothobranchius guentheri (p < 0.05), reduced the accumulation of lipofuscin (LF) (p < 0.05) in the gills and senescence-associated ß-galactosidase (SA-ß-Gal) (p < 0.05) in the caudal fins, and lowered the levels of protein oxidation (p < 0.05), lipid peroxidation (p < 0.01), and reactive oxygen species (ROS) (p < 0.01) in the muscles and livers, indicating that KO possesses rejuvenation and anti-aging activity. We also showed that KO enhanced the activities of antioxidant enzymes catalase (CAT) (p < 0.05), superoxide dismutase (SOD) (p < 0.05), and glutathione peroxidase (GPX) (p < 0.05) in aged male N. guentheri. In addition, KO administration effectively reversed histological lesions including inflammatory cell infiltration and structural collapse in the muscles and livers of aged N. guentheri and suppressed the nuclear factor kappa-B (NF-κB) signaling pathway (p < 0.05), a master regulator of inflammation. Altogether, our study indicates that KO has anti-aging and rejuvenation property. It also suggests that KO exerts its anti-aging and rejuvenation effects via enhancement of the antioxidant system and suppression of the NF-κB signaling pathway.

Versatile Bilayer Hydrogel for Wound Dressing through PET-RAFT Polymerization.

Multifunctional hydrogel-based wound dressings have been explored for decades due to their huge potential in multifaceted medical intervention to wound healing. However, it is usually not easy to fabricate a single hydrogel with all of the desirable functions at one time. Herein, a bilayer model with an outer layer for hydrogel wound dressing was proposed. The inner layer (Hm-PNn) was a hybrid hydrogel prepared by N-isopropylacrylamide and chitosan-N-2-hydroxypropyl trimethylammonium chloride (HACC), and the outer layer (PVAo-PAmp) was prepared by polyvinyl alcohols and acrylamide. The two hydrogel layers of the bilayer model were covalently connected with excellent interfacial strength by photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The outer layer exposed to the ambient environment exhibited good stretchability and toughness, while the inner-layer hydrogel adhered to the skin exhibited excellent softness, antibacterial activity, thermoresponsivity, and biocompatibility. In particular, the inner layer of a hydrogel demonstrated excellent antibacterial capability toward both Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria. Cell cytotoxicity showed that the cell viability of all Hm-PNn layer hydrogels exceeds 80%, confirming that the hydrogels bear excellent biocompatibility. In vivo experimental results indicated that the Hm-PNn/PVAo-PAmp bilayer hydrogel has a significant effect on the acceleration of wound healing, which was demonstrated in a full-thickness skin defect model showing improved collagen disposition and granulation tissue thickness. With these results, the established multifunctional bilayer hydrogel exhibits potential as an excellent wound dressing for wound healing applications, especially for open and infected traumas.

Preparation process optimization, structural characterization and in vitro digestion stability analysis of Antarctic krill (Euphausia superba) peptides-zinc chelate.

In the study, a novel kind of peptides-zinc (AKP-Zn) chelate was obtained using the Antarctic krill (Euphausia superba) peptides (AKP) as raw material, the reaction was carried out with the mass ratio of the AKP to ZnSO4·7H2O of 1:2 at pH 6.0 and 60 °C for 10 min. The structure and composition of the AKP, including particle size, Zeta potential, molecular weight distribution, amino acid composition, microstructure and surface elemental composition, changed significantly after chelating with zinc. The result of Fourier transform infrared spectroscopy indicated that zinc could be chelated by carboxyl oxygen and amino nitrogen atoms of the AKP. Furthermore, compared with zinc sulfate and zinc gluconate, the AKP-Zn chelate was more stable at various pH conditions and the simulated gastrointestinal digestion experiment. These findings would provide a scientific basis for developing new zinc supplements and the high-value utilization of Antarctic krill protein resource.

Chitin from Antarctic krill shell: Eco-preparation, detection, and characterization.

Antarctic krill is a nutrient-rich crustacean that is one of the main species in the Antarctic ecosystem. Antarctic krill shell (AKS) can be used as raw materials to prepare chitin. In this study, lactic acid and dispase were used to prepare Antarctic krill chitin (AKC-1). Amino-monosaccharide contents of chitin samples were detected by pre-column PMP-HPLC method. Analytical instruments were conducted to determine characteristics of chitin samples. Results showed that the amino-monosaccharide content of AKS was 4.62 g/100 g (measured in D-glucosamine). The yield of AKC-1 was 5.49 g/100 g, and the amino-monosaccharide content was 80.90 g/100 g. AKC-1 showed smooth flakes, a porous surface, and α-chitin structural characteristics. The maximum degradation temperature (DTGmax) was 318.3 °C. The yield of deacetylated chitin (AKC-2) was 4.74 g/100 g, with deacetylation degree of 80.8%, viscosity average molecular weight of approximately 145.7 kDa, and amino-monosaccharide content of 97.06 g/100 g. The surface morphology of AKC-2 was similar to that of AKC-1, and the DTGmax was 311.5 °C. A mild, eco-friendly chitin preparation method and an amino-monosaccharide content detection method of raw material before chitin preparation are described in this study, which can provide technical support for comprehensive utilization of Antarctic krill resources.

Effects of Drying Methods on the Content, Structural Isomers, and Composition of Astaxanthin in Antarctic Krill.

Antarctic krill (Euphausia superba) is one of the important bioresources in Antarctic waters, containing many bioactives (e.g., astaxanthin), which have a highly potential value for commercial exploitation. In this study, the effects of processing methods on the content, structural isomers, and composition of astaxanthins (free astaxanthin and astaxanthin esters) were studied. Three drying methods, comprising freeze-drying, microwave drying, and hot-air drying, were used. Free astaxanthin (Ast), astaxanthin monoesters (AM), and astaxanthin diesters (AD) in boiled krill (control) and dried krill were extracted and analyzed using high-resolution mass spectrometry with ultraviolet detection. After the three processes, total astaxanthin loss ranged from 8.6 to 64.9%, and the AM and AD contents ranged from 78.3 to 16.6 and 168.7 to 90.5 µg/g, respectively. Compared to other kinds of astaxanthin esters, astaxanthin esters, which linked to eicosapentaenoic acid and docosahexaenoic acid, as well as the Ast, were more easily degraded, and AM was more susceptible to degradation than AD. All-E-astaxanthin easily transformed to the 13Z-astaxanthin than to the 9Z-astaxanthin during the drying process, but the proportions of optical isomers changed due to drying by no more than 5%. The results suggested that freeze-drying, low-power microwave drying (≤1 kW), and low-temperature hot-air drying (≤60 °C) are optimal drying methods for ensuring the quality of krill products.

Sea cucumber cerebrosides and long-chain bases from Acaudina molpadioides protect against high fat diet-induced metabolic disorders in mice.

Metabolic syndrome (MS) is a cluster of metabolic disorders such as abdominal obesity, hypertension, glucose intolerance, dyslipidemia and hepatic steatosis that contribute to increased cardiovascular morbidity and mortality. There is an urgent need for strategies to prevent this emerging global epidemic. Recently, growing interest in discovering food functional nutrients for the prevention and treatment of MS has generated. In the present study, sea cucumber cerebrosides (SCC) and the main structural units, long-chain bases (LCB), were prepared from Acaudina molpadioides and then administered to high fat (HF) diet-induced obese C57BL/6J mice at a diet supplement dosage of 0.025% for 5 weeks to evaluate their effects on obesity-related metabolic disorders. SCC and LCB significantly decreased epididymal adipose tissue weights, lowered hepatic triacylglycerol levels, and reduced serum glucose, insulin levels and HOMA-IR index in mice. The activities of hepatic lipogenetic enzymes including FAS, ME and the mRNA levels of SREBP-1c and FAS were reduced by SCC and LCB treatment. However, SCC and LCB showed no effect on the hepatic lipolysis pathway. Besides, SCC and LCB also efficiently up-regulated the gene expression of SREBP-1c, FAS, ACC, ATGL and HSL, and down-regulated the gene expression of LPL and VLDL-r in the adipose tissue. These results demonstrated that SCC and LCB were efficacious in suppressing hepatic SREBP-1c mediated lipogenesis, inhibiting lipid uptake and increasing TG catabolism in the adipose tissue. The ameliorative degree and regulatory mechanisms of these two compounds were basically the same, suggesting that LCB are the key active structural units. Such findings would offer new insight into the application of SCC or LCB in the development of functional foods for preventing MS in humans.

[Simultaneous determination of 33 quinolone and sulfonamide residues in eels and shrimps by high performance liquid chromatography-tandem mass spectrometry].

The method for the simultaneous determination of 33 quinolone (QN) and sulfonamide (SA) residues in eels and shrimps was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The deuterium substituted reagents which were used as internal standards were added to the sample before the extraction. The sample was extracted with acidified acetonitrile, cleaned-up by hexane, and concentrated with a rotary evaporator. The mass spectrometer was operated in the positive ion mode using selected reaction monitoring for the qualitative and quantitative analysis of 33 SAs and QNs at the same time. The limits of detection for 33 SAs and QNs were 1.0 microg/kg (S/N = 3), and the limits of quantification were 2.0 microg/kg (S/N = 10). The correlation coefficients of linear calibration curves were over 0.99 in the concentration range of 10.0-200.0 microg/L. The average recoveries for 33 SAs and QNs were between 66% and 123%. The advantages of the method are simple operation and low cost. The method realized fast routine analysis.