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Abstract This study aimed to purify and characterize immunoregulatory peptides from Sipunculus nudus L. and to explore the underlying mechanisms. Ultrafiltration, gel filtration chromatography, and reverse phase high‐performance liquid chromatography (RP‐HPLC) were used to purify the peptide following enzymatic hydrolysis. Rates of lymphocyte proliferation and phagocytosis as well as nitric oxide (NO) production levels were used as indicators of immunoregulatory activity to screen the fractions. The amino acid sequence of the peptide, designated as SNLP, was identified as Arg–Val–Lys–Gly–Lys–Ile–Leu–Ala–Lys–Arg–Leu–Asn (RVKGKILAKRLN) by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Treatment with the synthetic SNLP increased the proliferation and phagocytosis of RAW 264.7 macrophages and promoted the secretion of tumor necrosis factor‐ɑ (TNF‐α), interleukin‐6 (IL‐6), interleukin‐1β (IL‐1β), and NO levels. The mRNA levels of these cytokines and iNOS were also increased by SNLP. Our results provide preliminary evidence suggesting that SNLP acts as a dual immunomodulatory peptide with immunostimulatory and anti‐inflammatory activities. In summary, SNLP derived from Sipunculus nudus L. is a potent immunoregulatory peptide and represents a potential functional food or immunoregulatory drug.

Pearl and nacre powders have been valuable traditional Chinese medicines with whitening properties for thousands of years. We utilized a high-temperature and high-pressure method along with compound enzyme digestion to prepare the enzymatic hydrolysates of nacre powder of Pinctada martensii (NP-PMH). The peptides were identified using LC–MS/MS and screened through molecular docking and molecular dynamics simulations. The interactions between peptides and tyrosinase were elucidated through enzyme kinetics, circular dichroism spectropolarimetry, and isothermal titration calorimetry. Additionally, their inhibitory effects on B16F10 cells were explored. The results showed that a tyrosinase-inhibitory peptide (Ala-His-Tyr-Tyr-Asp, AHYYD) was identified, which inhibited tyrosinase with an IC50 value of 2.012 ± 0.088 mM. The results of the in vitro interactions showed that AHYYD exhibited a mixed-type inhibition of tyrosinase and also led to a more compact enzyme structure. The binding reactions of AHYYD with tyrosinase were spontaneous, leading to the formation of a new set of binding sites on the tyrosinase. The B16F10 cell-whitening assay revealed that AHYYD could reduce the melanin content of the cells by directly inhibiting the activity of intracellular tyrosinase. Additionally, it indirectly affects melanin production by acting as an antioxidant. These results suggest that AHYYD could be widely used as a tyrosinase inhibitor in whitening foods and pharmaceuticals.

Colitis causes inflammation, diarrhoea, fever, and other serious illnesses, posing a serious threat to human health and safety. Current medications for the treatment of colitis have serious side effects. Therefore, the new strategy of creating a defence barrier for immune function by adding anti-inflammatory foods to the daily diet is worth advocating for. Low-molecular weight oyster peptides (LOPs) are a natural food with anti-inflammatory activity extracted from oysters, so intervention with LOPs is likely to be an effective preventive solution. The aim of this study was to investigate the preventive effect of LOPs on lipopolysaccharide (LPS)-induced acute colitis inflammation in mice and its underlying mechanism. The results showed that LOPs not only inhibited the colonic histopathy in mice induced by LPS-induced inflammation but also reduced the inflammatory response in the blood. In addition, LOPs significantly increased the number of beneficial bacteria (Alistipes, Mucispirillum, and Oscillospira), decreased the number of harmful bacteria (Coprobacillus, Acinetobater) in the intestinal microbiota, and further affected the absorption and utilisation of short-chain fatty acids (SCFAs) in the intestinal tract. In conclusion, dietary supplementation with LOPs is a promising health-promoting dietary supplement and nutraceutical for the prevention of acute colitis by reducing the inflammatory response and modulating the intestinal microbial communities.

Remote sensing satellite SiCH-2 from Ukraine was launched in 2011. At present, it has stopped working and is out of control, and it has been forecasted to become space debris by a two-line root (TLE) from the North American Air Defense Command (NORAD). Here, the "cat's eye" effect of the optical system is analyzed, and the satellite laser ranging (SLR) system at Shanghai Observatory is used to measure the echo intensity of satellite SiCH-2, which is very strong, and the ranging accuracy, which is better than 10 cm. The analysis of the measurement capability results shows that the laser reflection echo from satellite SiCH-2 reaches the laser ranging level of the satellite with the reflector, and is consistent with the detection ability of the photoelectric detection equipment "cat's eye" effect analysis. The measurement results also show that satellite SiCH-2 is in a state of rotation, with a period of 4.3 s. In this study, the laser ranging of on-orbit targets based on the "cat's eye" effect is realized for the first time, which provides a new method for analyzing long-distance space targets, promotes the application and development of high-precision laser ranging technology, and is beneficial to monitor the photoelectric detection series of satellites that fail or have abnormal orbits.

This study was conducted to investigate functional, physicochemical, and structural properties of abalone foot muscle proteins (AFPs) and their hydrolysates (HAFPs) obtained using animal protease (HA), papain (HPP), and Protamex® (HP) at different time points. The HA-hydrolysate obtained after 0.5 h of treatment demonstrated the highest solubility at pH 7.0 (84.19%); the HPP-hydrolysate at 4 h exhibited the highest degree of hydrolysis (11.4%); the HPP-hydrolysate at 0.5 h had the highest oil holding capacity (2.62 g/g) and emulsion stability index (39.73 min), and the HP-hydrolysate at 4 h had the highest emulsifying activity index (93.23 m2/g) and foaming stability (91.45%); Regarding the physicochemical properties, the HPP-hydrolysates revealed the largest particle size, higher absolute zeta potential, and superior interfacial activity. Structural characterization demonstrated the enzymolysis-based changes in the composition and the secondary structure of the AFPs. These results provide practical support for the theoretical basis of the use of AFPs as a source of nutritive proteins in the food industry.

In our previous study, two peptides with favorable anti-inflammatory effects, Asp-Gln-Thr-Phe (DQTF) and Gly-Tyr-Thr-Arg (GYTR), were screened from Ruditapes philippinarum using an in vitro–in silico strategy. The present study aims to investigate the ameliorative effect of Ruditapes philippinarum peptides (RPPs) on acute inflammation and clarify the potential mechanism through in vitro and in vivo experiments. The anti-inflammatory effects of DQTF and GYTR were verified with a lipopolysaccharide (LPS)-induced RAW264.7 cell acute inflammation model and the anti-inflammatory effect of the enzymatic hydrolysates of Ruditapes philippinarum was explored in vivo using an LPS-induced acute inflammatory injury model in mice. The results show that DQTF and GYTR improved the morphology of LPS-injured cells and decreased the concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in LPS-induced cells. Moreover, the antioxidant enzyme activity in cells was markedly increased with DQTF and GYTR. The enzymatic hydrolysates of Ruditapes philippinarum were obtained with hydrolysis using pepsin–chymotrypsin–trypsin (PeCTHC) and pepsin–trypsin (PeTHC), respectively. PeCTHC and PeTHC significantly reduced pro-inflammatory cytokines and nitric oxide (NO) in the serum. Additionally, the blood indices and levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in the livers of mice were markedly improved with RPPs administration. In conclusion, RPPs have preventive and protective effects on acute inflammation, with significant prospects for development in the field of functional foods.

Oysters contain significant amounts of the zinc element, which may also be found in their proteins. In this study, a novel zinc-binding protein was purified from the mantle of the oyster Magallana hongkongensis using two kinds of gel filtration chromatograms. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) showed that its molecular weight was approximately 36 kDa. The protein identified by the Q-Exactive mass spectrometer shared the highest sequence identity with carbonic anhydrase derived from Crassostrea gigas concerning amino acid sequence similarity. Based on homologous cloning and RACE PCR, the full-length cDNA of carbonic anhydrase from Magallana hongkongensis (designated as MhCA) was cloned and sequenced. The cDNA of MhCA encodes a 315-amino-acid protein with 89.74% homology to carbonic anhydrase derived from Crassostrea gigas. Molecular docking revealed that the two zinc ions primarily form coordination bonds with histidine residues in the MhCA protein. These results strongly suggest that MhCA is a novel zinc-binding protein in Magallana hongkongensis.

Abstract Introduction Oxidative stress and inflammatory responses are often the predominant detrimental factors associated with spinal cord injury (SCI). This study investigates the potential therapeutic effects of albiflorin (AF) on alleviating inflammation and oxidative stress in the rat model with SCI. Methods Initially, the behavior of SCI‐induced rats is examined by Basso−Beattie−Bresnahan score and the inclined plane examination. Then, the immunohistochemical staining of inflammasome‐related protein (for instance, NACHT, LRR, and PYD domains‐containing protein 3, NLRP3) is performed in combination with enzyme‐linked immunosorbent assay (ELISA) of corresponding proinflammatory factors to assess the immunomodulatory effects of AF. Further, the markers involved in oxidative stress are examined by ELISA and western blot analysis analyses. Results These findings indicated that AF could alleviate motor dysfunction and the loss of neuron cells in SCI‐induced rats. Mechanistically, AF could attenuate the inflammatory responses by reducing oxidative stress and activating nuclear erythroid‐related factor 2 (Nrf2)/heme oxygenase‐1 (HO‐1) pathway in SCI rats. Depleting the antioxidant capacity by inhibiting glutathione biosynthesis could counteract the anti‐inflammatory activity of AF in SCI rats. Conclusions Together, our data suggested that AF could serve as a potential therapeutic agent against the aggravation of SCI in rats.

ObjectiveTo study the clinical features of children diagnosed with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) in southern China.MethodsClinical data of children diagnosed with MOGAD from April 2014 to September 2021 were analyzed.ResultsA total of 93 children (M/F=45/48; median onset age=6.0 y) with MOGAD were involved. Seizures or limb paralysis was the most common onset or course symptom, respectively. The most common lesion locations in brain MRI, orbital MRI, and spinal cord MRI were basal ganglia and subcortical white matter, the orbital segment of the optic nerve, and the cervical segment, respectively. ADEM (58.10%) was the most common clinical phenotype. The relapse rate was 24.7%. Compared with the patients without relapse, relapsed patients had a longer interval from onset to diagnosis (median: 19 days VS 20 days) and higher MOG antibody titer at onset (median: 1:32 VS 1:100) with longer positively persistent (median: 3 months VS 24 months). All patients received IVMP plus IVIG at the acute phase, and 96.8% of patients achieved remission after one to three courses of treatment. MMF, monthly IVIG, and maintaining a low dose of oral prednisone were used alone or in combination as maintenance immunotherapy for relapsed patients and effectively reduced relapse. It transpired 41.9% of patients had neurological sequelae, with movement disorder being the most common. Compared with patients without sequelae, patients with sequelae had higher MOG antibody titer at onset (median: 1:32 VS 1:100) with longer persistence (median: 3 months VS 6 months) and higher disease relapse rate (14.8% VS 38.5%).ConclusionsResults showed the following about pediatric MOGAD in southern China: the median onset age was 6.0 years, with no obvious sex distribution difference; seizure or limb paralysis, respectively, are the most common onset or course symptom; the lesions of basal ganglia, subcortical white matter, the orbital segment of the optic nerve, and cervical segment were commonly involved in the CNS MRI; ADEM was the most common clinical phenotype; most had a good response to immunotherapy; although the relapse rate was relatively high, MMF, monthly IVIG and a low dose of oral prednisone might effectively reduce relapse; neurological sequelae were common, and possibly associated with MOG antibody status and disease relapse.

Di-(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer, which can cause damage to male reproductive organs, especially the atrophy of the testis. Meanwhile, DEHP can also lead to a decrease in testicular zinc content, but the role of zinc remains unclear. This study aims to prepare oyster peptide-zinc complex (OPZC) to alleviate DEHP-induced reproductive damage in mice. OPZC was successfully obtained through electron microscopy, X-ray diffraction, and thermogravimetric analysis, with stable structure and high water-solubility. Low dose oyster peptide-zinc complex (OPZCL) significantly reduced the reproductive damage caused by DEHP in mice. Further research had shown that OPZCL restored the content of serum hormones and the activity of oxidative stress kinases to normal, while also normalizing testicular zinc and selenium levels. In addition, it also recovered the disorder of gut microbiota, reduced the proportion of Bacteroides, increased the abundance of Ligilactobacillus, and restored the proportion of Acidobacteriota, Chloroflexi, and Proteobacteria. Therefore, OPZCL can relieve the reproductive damage caused by DEHP in mice by restoring testicular zinc homeostasis and the composition of intestinal microbiota, indicating that OPZCL has a potential protective effect on male reproductive health.

In order to realize the multi-level utilization of marine shellfish resources and to develop the potential biological activity of processing by-products of Atrina pectinata, gelatin was extracted from the mantle and the potential whitening effect of its enzymatic peptides was explored. Taking tyrosinase inhibitory activity as the evaluation index, the enzyme hydrolysate process was optimized by response-surface methodology, and the optimal enzyme hydrolysate conditions were as follows: pH 5.82, 238 min enzyme hydrolysate time, and temperature of 54.5 °C. Under these conditions, the tyrosinase inhibition activity of Atrina pectinata mantle gelatin peptide (APGP) was 88.6% (IC50 of 3.268 ± 0.048 mg/mL). The peptides obtained from the identification were separated by ultrafiltration and LC–MS/MS, and then four new peptides were screened by molecular docking, among which the peptide Tyr-Tyr-Pro (YYP) had the strongest inhibitory effect on tyrosinase with an IC50 value of 1.764 ± 0.025 mM. The molecular-docking results indicated that hydrogen bonding is the main driving force for the interaction of the peptide YYP with tyrosinase. From the Lineweaver–Burk analysis, it could be concluded that YYP is inhibitory to tyrosinase and exhibits a mixed mechanism of inhibition. These results suggest that YYP could be widely used as a tyrosinase inhibitor in whitening foods and pharmaceuticals.

To improve the quality and food safety of live shellfish, solve the problems of low depuration efficiency, difficulty in pollutants desorption and the loss during depuration. In this paper, the accumulation and metabolism of pollutants, depuration methods, key factors of depuration effect of shellfish are discussed, combination and optimization of depuration methods, cold sterilization technology are recommended to use during depuration. Research on the application of probiotic in the depuration, development of green and efficient safe purification agents and new depuration equipment, modern depuration plants design, timely formulate and update industry standards for shellfish depuration are presented as suggestions in the paper to provide a reference for in-depth research on shellfish depuration.

Ultrasonic-assisted treatment is an eco-friendly and cost-effective emulsification method, and the acoustic cavitation effect produced by ultrasonic equipment is conducive to the formation of stable emulsion. However, its effect on the underlying stability of low-molecular-weight oyster peptides (LOPs) functional-nutrition W1/O/W2 double emulsion has not been reported. The effects of different ultrasonic power (50, 75, 100, 125, and 150 W) on the stability of double emulsions and the ability to mask the fishy odor of LOPs were investigated. Low ultrasonic power (50 W and 75 W) treatment failed to form a well-stabilized double emulsion, and excessive ultrasound treatment (150 W) destroyed its structure. At an ultrasonic power of 125 W, smaller particle-sized double emulsion was formed with more uniform distribution, more whiteness, and a lower viscosity coefficient. Meanwhile, the cavitation effect generated by 125 W ultrasonic power improved storage, and oxidative stabilities, emulsifying properties of double emulsion by reducing the droplet size and improved sensorial acceptability by masking the undesirable flavor of LOPs. The structure of the double emulsion was further confirmed by optical microscopy and confocal laser scanning microscopy. The ultrasonic-assisted treatment is of potential value for the industrial application of double emulsion in functional-nutrition foods.

Low-molecular-weight oyster peptides (LOPs) are typical bioactive peptides with ameliorated immunomodulatory properties. However, the mechanism underlying its effect on immune functions and intestinal flora after chemotherapy has not been reported. In this study, Lewis lung cancer mice were used along with cytotoxic chemotherapy to establish model to investigate the ameliorative effects of LOPs on immunomodulatory function and intestinal flora structure. Our results showed that administration of LOPs alleviated weight loss, reduced spleen tissue damage, increased splenic T-lymphocytes, and markedly increased secretion of serum immunoglobulins and decreased inflammatory factors. Additionally, LOPs significantly increased the abundance of beneficial bacteria (Lactobacillus and Coriobacteriaceae_UCG) and decreased pathogenic bacteria (Clostridium) present in intestine. Hydrophobic amino acids and glutamate may be the underlying components to mitigate negative effects of chemotherapy. This study provides a theoretical basis for the use of LOPs as a nutritional base for the development of formula foods for cancer patients undergoing chemotherapy.

Oysters are nutritious and tasty but difficult to store. Drying can extend the storage period of oysters and give them a unique flavor. In this study, the effects of four drying procedures, namely, vacuum freeze drying (VFD), vacuum drying (VD), natural sun-drying (NSD), and hot air drying (HAD), on the flavor characteristics of oysters (Crassostrea hongkongensis) were investigated using blanched oysters as a control (CK). Results showed that HAD produced more free amino acids than the other methods, but VFD retained the most flavor nucleotides. Compared with cold drying (VFD), hot drying (VD, NSD, and HAD) increased the abundance of organic acids, betaine, and aroma substances. Glutamic acid, alanine, AMP, hexanal, octanal, heptanal, (E, E)-2,4-heptadienal, (E)-2-decenal, nonanal, etc., are defined as the characteristic flavor compounds of dried oysters, with umami, sweet, green, fatty, and fruity aromas being the main organoleptic attributes of dried oysters. Glutamic acid, glycine, betaine, IMP, pentanal, ethyl heptanoate, (E, Z)-2,4-nonadienal, 1-octen-3-one, 2-hexenal, 2-octenal, hexanal, decanal were defined as markers to distinguish different drying methods. Overall, HAD showed improved flavor qualities and characteristics and was better suited for the highly commercialized production of dried oysters.

Abstract The coating material of a tool directly affects the efficiency and cost of machining malleable cast iron. However, the machining adaptability of various coating materials to malleable cast iron has been insufficiently researched. In this paper, turning tests were conducted on cemented carbide tools with different coatings (a thick TiN/TiAlN coating, a thin TiN/TiAlN coating, and a nanocomposite (nc) TiAlSiN coating). All coatings were applied by physical vapor deposition. In a comparative study of chip morphology, cutting force, cutting temperature, specific cutting energy, tool wear, and surface roughness, this study analyzed the cutting characteristics of the tools coated with various materials, and established the relationship between the cutting parameters and machining objectives. The results showed that in malleable cast iron machining, the coating material significantly affects the cutting performance of the tool. Among the three tools, the nc-TiAlSiN-coated carbide tool achieved the minimum cutting force, the lowest cutting temperature, least tool wear, longest tool life, and best surface quality. Moreover, in comparisons between cemented-carbide and compacted-graphite cast iron machined under the same conditions, the wear mechanism of the coated tools was found to depend on the cast iron being machined. Therefore, the performance requirements of a tool depend on multiple factors, and selecting an appropriately coated tool for a particular cast iron material is essential.

Pinctada martensii protein isolates (PPIs) and polysaccharide complexes of different mixing ratios (10:1, 10:2, 10:3) were prepared at the optimal pH. The characteristics of PPIs and complexes were compared by determination of solubility, emulsifying properties, surface hydrophobicity, thermal properties, rheological behavior, and fourier transform infrared (FT-IR) spectroscopy. Compared with PPIs, the solubility of complexes changed to different degrees, and 10:3 PPI-pectin complex had the highest solubility (10.02 ± 0.68%). The emulsion properties of 10:2 and 10:3 PPI-alginate complexes were significantly higher than produced from other systems. The conjugation of PPI and pectin evidently reduced surface hydrophobicity of PPI. Denaturation temperatures of complexes were generally higher than that of PPIs. The gel network of PPI and complexes was formed within 70–80°C at pH 7.0 and G′ values of complexes were lower than that of PPIs. FT-IR spectroscopy showed O-H stretching of water absorption, C-C and C-O stretching and C-H bending of colloidal polysaccharides were improved in complexes.

Dissolved oxygen (DO) is an key factor for lipopeptide fermentation. To better understand the link between oxygen supply and lipopeptide productivity in Bacillus velezensis CMT-6, the mechanism of DO on the synthesis of antimicrobial lipopeptides by Bacillus velezensis CMT-6 was examined. The production of surfactin and iturin of CMT-6 was detected by liquid chromatography–mass spectrometer (LC-MS) under different DO conditions and transcriptome analysis was performed. At 100 and 200 rpm, the lipopeptides productions were 2753.62 mg/L and 3452.90 mg/L, respectively. There was no significant change in the yield of iturin but that of surfactin increased by 64.14%. Transcriptome analysis revealed that the enriched differential genes were concentrated in the GO term of oxidation–reduction process. The marked enrichment of the lipopeptides synthesis pathway, including microbial metabolism in diverse environments and carbon metabolism in the two-component system, were observed. More importantly, the expression levels of the four surfactin synthetase genes increased at higher DO, however, the iturin synthetase gene expression did not. Furthermore, modular surfactin synthetase was overexpressed (between 9- and 49-fold) at 200 rpm but not at 100 rpm, which is suggestive of efficient surfactin assembly resulting in surfactin overproduction. This study provides a theoretical basis for constructing engineering strains with high lipopeptide production to adapt to different DO.

Protein content, a vital component determining the nutritional quality of oysters, is unevenly distributed in different parts of oyster. In this study, the spatial distribution (visceral mass, mantle, gill, and adductor) patterns and structural characteristics of proteins, including water–soluble proteins (WSP), salt–soluble proteins (SSP), acid–soluble proteins (ASP) and alkali–soluble proteins (ALSP) of oysters (Crassostrea hongkongensis) were investigated with the amino acid analyzer, circular dichroism spectroscopy (CD), fourier transform infrared spectroscopy (FTIR), and fluorescence spectroscopy. The results showed that oyster proteins were mainly distributed in the visceral mass and mantle. The protein composition was WSP, SSP, ALSP, and ASP in descending order, which conformed to the ideal amino acid pattern. Variations in secondary structure, molecular weight distribution, and thermal denaturation temperatures of the oyster proteins were observed. SSP had wider bands (16–270 kDa) than those of ASP (30–37 kDa) and ALSP (66–270 kDa). Among the four proteins, the SSP of the mantle showed the highest thermal stability (87.4 °C), while ALSP of the adductor muscle had the lowest the lowest the peak denaturation temperature (Tm) (53.8 °C). The proportions of secondary structures in oyster proteins were different, with a higher proportion of solid protein β–folds, and the exposure of aromatic amino acid residues and disulfide bonds and the microenvironment in which they were located were also different.

When bees carry pollen, it sticks to their legs and it can be carried without being dropped in a range of different humidity conditions. Here the authors find that the adhesive holding the pollen together consists of two phases and the oily phase stabilizes the aqueous phase with respect to humidity changes.

Previous studies found that both oral and topical administration of enzymatic digestion products < 3 K Da ultrafiltration fractions of Pinctada martensii mantle (PMPs) had pro-healing effects. Thus, we further purified them by Sephadex-G25 and screened them by cellular assays to obtain Pinctada martensii purified peptides (PMPPs). In this study, we explored the mechanism of PMPPs on wound healing by in vivo, in vitro, and in silico experiments. LC-MS/MS results showed that PMPPs consisted of 33 peptides with molecular weights ranging from 758.43 to 2014.04 Da, and the characteristic peptide was Leu-Asp. The results of cellular assays showed that PMPPs promoted the proliferation of human skin fibroblasts (HSF) (135%) and human immortalized keratinocyte (HaCaT) cells (125%) very significantly at 12.5 μg/mL. The in vivo results showed that PMPPs could achieve scarless healing by inhibiting the inflammatory response, accelerating the epithelialization process, and regulating collagen I/III ratio. The optimal peptide sequence FAFQAEIAQLMS of PMPPs was screened for key protein receptors in wound healing (EGFR1, FGFR1, and MMP-1) with the help of molecular docking technique, which also showed to be the key pro-healing active peptide sequence. Therefore, it may provide a therapeutic strategy with great potential for wound healing.

Oyster meat has a tender texture and delicate flavor, and the oyster is an aquatic shellfish with high nutritional and economic values. As they are rich in protein, oysters serve as a good source for the preparation of bioactive peptides. However, research on the lactation effect and mechanism of the synthesis of polypeptides from oyster hydrolysates is yet to be observed. This study aimed to analyze the lactation activity of the fraction UEC4-1 and explore its mechanism. The results show that, in an in vivo experiment, UEC4-1 could significantly increase the concentration of PRL in the serum and mammary tissue and the concentration of PRLR in the mammary tissue in rats with postpartum hypogalactia. UEC4-1 promoted the development of mammary tissue structure, resulting in active lactation. UEC4-1 promoted the proliferation of MCF-10A in a dose-dependent manner and could significantly upregulate the gene expression levels of PRL, PRLR, CSN1S1, CSN2, CSN3 and CCND1. UEC4-1 could also significantly increase the expression of mTOR, AKT1, RPS6KB1 and STAT5A in MCF-10A and improve its phosphorylation level. These results show that UEC4-1 had the ability to upregulate the proliferation and PRL synthesis of MCF-10A and promote lactation. The ability of UEC4-1 to regulate the milk-protein synthesis signaling pathway is the mechanism behind this. Oysters had a remarkable effect on lactating mothers’ sweating irritability after childbirth and may serve as an everyday diet to promote lactation. Postpartum dysgalactia is a common problem for lactating women. The study of the oyster’s lactation-active peptide can provide dietary nutrition guidance for postpartum lactating mothers, and it has the potential to be used for the development of drugs for the treatment of postpartum hypogalactia or oligogalactia.

Previous studies have revealed that excessive exposure to UV irradiation is the main cause of skin photoaging and the signaling pathways of MAPK and NF-κB are involved in this progression. The present study aims to investigate the anti-photoaging effects of low molecular weight hydrolysates from Theragra chalcogramma (TCH) and to clarify the underlying mechanism. The degradation of mechanical barrier functions in photoaged skin was substantially ameliorated after TCH administration; meanwhile, TCH significantly elevated the antioxidant capacity and suppressed the over-production of inflammatory cytokine IL-1β. Moreover, the histopathological deteriorations such as epidermal hyperplasia and dermal loss were significantly alleviated, along with the increase in procollagen type I content and decrease in MMP-1 activity (p < 0.05). Furthermore, TCH effectively blocked the MAPK and NF-κB signaling pathways through inhibition of the phosphorylation of p38, JNK, ERK, iκB, and p65 proteins. Collectively, these data indicate that TCH has potential as a novel ingredient for the development of anti-photoaging foods.

Enzymatic hydrolysates from Oysters (OAH) display multiple biological activities. Previously, a 3~5 KDa oyster ultrafiltration component (OUP) showed a high property of preventing skin oxidation. Subsequently, we identified specific peptides with such activity. OUP was fractionated stepwise by Sephadex-G25 and RP-HPLC, and active fractions were screened using UV-irradiated HaCaT cells. The most active fractions (OP5-3) were analyzed by LC-MS/MS and a total of 17 peptides were identified. Results from mass spectrometry showed that OP5-3 consisted of peptides with a molecular weight range of 841.51–1786.92 Da. Six of these peptides were synthesized for validating the activity of resisting skin oxidation in the same cell model. All six peptides showed varying degrees of antioxidant activity, while pretreatment of HaCaT cells with AIVAEVNEAAK alleviated UV cytotoxicity, inhibited metalloproteinase 1 (MMP-1) expression, and showed the highest activity to resist UV-induced skin photo-oxidation among these peptides. In addition, results from molecular docking analysis of MMP-1 with AIVAEVNEAAK showed that AIVAEVNEAAK suppresses its enzymatic activity by directly interacting with MMP-1 and thus exhibit anti-photoaging activity.

Peptides from oyster hydrolysate (OPs) have a variety of biological activities. However, its protective effect and exact mechanism on testicular injury remain poorly understood. This study aimed to evaluate the protective effect of OPs on triptolide (TP)-induced testis damage and spermatogenesis dysfunction and investigate its underlying mechanism. In this work, the TP-induced testis injury model was created while OPs were gavaged in mice for 4 weeks. The results showed that OPs significantly improved the sperm count and motility of mice, and alleviated the seminiferous tubule injury. Further study showed that OPs decreased malonaldehyde (MDA) level and increased antioxidant enzyme (SOD and GPH-Px) activities, attenuating oxidative stress and thereby reducing the number of apoptotic cells in the testis. In addition, OPs improved the activities of enzymes (LDH, ALP and ACP) related to energy metabolism in the testis and restored the serum hormone level of mice to normal. Furthermore, OPs promoted the expression of Nrf2 protein, and then increased the expression of antioxidant enzyme regulatory protein (HO-1 and NQO1) in the testis. OPs inhibited JNK phosphorylation and Bcl-2/Bax-mediated apoptosis. In conclusion, OPs have a protective effect on testicular injury and spermatogenesis disorders caused by TP, suggesting the potential protection of OPs on male reproduction.

Marine collagen peptides have high potential in promoting skin wound healing. This study aimed to investigate wound healing activity of collagen peptides derived from Sipunculus nudus (SNCP). The effects of SNCP on promoting healing were studied through a whole cortex wound model in mice. Results showed that SNCP consisted of peptides with a molecular weight less than 5 kDa accounted for 81.95%, rich in Gly and Arg. SNCP possessed outstanding capacity to induce human umbilical vein endothelial cells (HUVEC), human immortalized keratinocytes (HaCaT) and human skin fibroblasts (HSF) cells proliferation and migration in vitro. In vivo, SNCP could markedly improve the healing rate and shorten the scab removal time, possessing a scar-free healing effect. Compared with the negative control group, the expression level of tumor necrosis factor-α, interleukin-1β and transforming growth factor-β1 (TGF-β1) in the SNCP group was significantly down-regulated at 7 days post-wounding (p < 0.01). Moreover, the mRNA level of mothers against decapentaplegic homolog 7 (Smad7) in SNCP group was up-regulated (p < 0.01); in contrast, type II TGF-β receptors, collagen I and α-smooth muscle actin were significantly down-regulated at 28 days (p < 0.01). These results indicate that SNCP possessed excellent activity of accelerating wound healing and inhibiting scar formation, and its mechanism was closely related to reducing inflammation, improving collagen deposition and recombination and blockade of the TGF-β/Smads signal pathway. Therefore, SNCP may have promising clinical applications in skin wound repair and scar inhibition.

Skin wound healing, especially chronic wound healing, is a common challenging clinical problem. It is urgent to broaden the sources of bioactive substances that can safely and efficiently promote skin wound healing. This study aimed to observe the effects of small molecular peptides (SMPs) of the mantle of Pinctada martensii on wound healing. After physicochemical analysis of amino acids and mass spectrometry of SMPs, the effect of SMPs on promoting healing was studied through a whole cortex wound model on the back of mice for 18 consecutive days. The results showed that SMPs consisted of polypeptides with a molecular weight of 302.17–2936.43 Da. The content of polypeptides containing 2–15 amino acids accounted for 73.87%, and the hydrophobic amino acids accounted for 56.51%. Results of in vitro experimentation showed that SMPs possess a procoagulant effect, but no antibacterial activity. Results of in vivo experiments indicated that SMPs inhibit inflammatory response by secretion of anti-inflammatory factor IL-10 during the inflammatory phase; during the proliferative phase, SMPs promote the proliferation of fibroblasts and keratinocytes. The secretion of transforming growth factor-β1 and cyclin D1 accelerates the epithelialization and contraction of wounds. In the proliferative phase, SMPs effectively promote collagen deposition and partially inhibit superficial scar hyperplasia. These results show that SMPs promotes dermal wound healing in mice and have a tremendous potential for development and utilization in skin wound healing.

The proliferation of pollution in aquatic environments has become a growing concernand calls for the development of novel adsorbents capable of selectively removing notorious andrecalcitrant pollutants from these ecosystems. Herein, a general strategy was developed for thesynthesis and functionalization of molecularly imprinted polymer microspheres (MIPs) that couldbe optimized to possess a significant adsorption selectivity to an organic pollutant in aqueousmedia, in addition to a high adsorption capacity. Considering that the molecular imprinting alonewas far from satisfactory to produce a high-performance MIPs-based adsorbent, further structuralengineering and surface functionalization were performed in this study. Although the more carboxylgroups on the surfaces of the MIPs enhanced the adsorption rate and capacity toward an organicpollutant through electrostatic interactions, they did not strengthen the adsorption selectivity in aproportional manner. Through a systematic study, the optimized sample exhibiting both impressiveselectivity and capacity for the adsorption of the organic pollutant was found to possess a smallparticle size, a high specific surface area, a large total pore volume, and an appropriate amount ofsurface carboxyl groups. While the pseudo-second-order kinetic model was found to better describethe process of the adsorption onto the surface of MIPs as compared to the pseudo-first-order kineticmodel, neither Langmuir nor Freundlich isothermal model could be used to well fit the isothermaladsorption data. Increased temperature facilitated the adsorption of the organic pollutant onto theMIPs, as an endothermic process. Furthermore, the optimized MIPs were also successfully employedas a stationary phase for the fabrication of a molecularly imprinted solid phase extraction column,with which purchased food-grade fish samples were effectively examined.