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.

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.

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.

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 active peptides (APs) of the mantle of Pinctada martensii on wound healing. After physicochemical analysis of amino acids and mass spectrometry of APs, the effect of APs on promoting healing was studied through a whole cortex wound model on the back of mice for 18 consecutive days. The results showed that APs consisted of polypeptides with molecular weights in the range 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 mice in APs-L group which were fed a low dose of APs (0.5 g/kg bw) had a shortened epithelialization time due to a shortening inflammatory period (p < 0.05). Mechanistically, this relied on its specific ability to promote the proliferation of CD31, FGF and EGF which accelerated the percentage of wound closure. Moreover, the APs-L group mice had enhanced collagen synthesis and increased type III collagen content in their wounds through a TGF-β/Smad signaling pathway (p > 0.05). Consequently, scar formation was inhibited and wound healing efficiency was significantly improved. These results show that the APs of Pinctada martensii promote dermal wound healing in mice and have tremendous potential for development and utilization in skin wound healing.

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.

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.

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.

Vernalization is required for floral initiation in Dendrobium. Interestingly, those beneficial effects can also be achieved by exogenous cytokinin application in greenhouses. Thus, an as yet unknown crosstalk/interaction may exist between vernalization and cytokinin signaling pathways. In this study, we showed, by de novo transcriptome assembly using RNA-seq data from both vegetative and reproductive tissue samples, that some floral transition-related genes-DnVRN1, FT, SOC1, LFY and AP1-were differentially expressed in low-temperature-challenged (LT) or thidiazuron (TDZ)-treated plants, compared to those mock-treated (CK). Both LT and TDZ upregulated SOC1, LFY and AP1, while the upregulation of DnVRN1 and FT was only LT-induced. We further found that LT promoted the upregulation of some key cytokinin signaling regulators, including several cytokinin biosynthesis-related genes and type-B response regulator (RR)-encoding genes, and that both LT and TDZ triggered the significant upregulation of some marker genes in the gibberellin (GA) signaling pathway, indicating an important low temperature-cytokinin-GA axis in flowering. Our data thus have revealed a cytokinin-GA signal network underlying vernalization, providing a novel insight into further investigation of the molecular mechanism of floral initiation in Dendrobium.

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.

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.

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.

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.