Identification of MMP-1 inhibitory peptides from cod skin gelatin hydrolysates and the inhibition mechanism by MAPK signaling pathway

Marine peptides as potential anti-aging agents: Preparation, characterization, mechanisms of action, and future perspectives

Aging is a universal biological process characterized by a decline in physiological functions, leading to increased susceptibility to diseases. With global aging trends, understanding and mitigating the aging process is paramount. Recent studies highlight marine peptides as promising bioactive substances with potential anti-aging properties. This review critically examines the potential of marine peptides as novel food ingredients in anti-aging, exploring their sources, preparation methods, physicochemical properties, and the underlying mechanisms through which they impact the aging process. Marine peptides exhibit significant potential in targeting aging, extending lifespan, and enhancing healthspan. They act through mechanisms such as reducing oxidative stress and inflammation, modulating mitochondrial dysfunction, inducing autophagy, maintaining extracellular matrix homeostasis, and regulating longevity-related pathways. Despite challenges in stability, bioavailability, and scalability, marine peptides offer significant potential in health, nutraceuticals, and pharmaceuticals, warranting further research and development in anti-aging.

Protective effect of ferulic acid-hyaluronic acid copolymer against UVB irradiation in a human HaCaT cell line

Excessive UVB exposure increased the production of reactive oxygen species (ROS), leading to oxidative damage and epidermal inflammation. To enhance UVB protection effect, a strong phenolic antioxidant, ferulic acid (FA) was designed onto HA via a free radical mediated method. Our previous work has confirmed its structural characterization and in vitro antioxidant. The aim of this study was to evaluate its protective effects against UVB-induced damage in human HaCaT cells. We observed a significant reduction in cell viability to 57.43 % following UVB exposure at a dose of 80 mJ/cm2. However, pretreatment with FA-HA (250 to 2000 μg·mL-1) significantly attenuated cytotoxicity in a dose-dependent manner. Furthermore, FA-HA was found to suppress the intracellular generation of ROS and up-regulated the expression of the antioxidant enzyme superoxide dismutase (SOD). The elevated levels of pro-inflammatory cytokines, including interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) as well as the mRNA expression of matrix metalloproteinase-1/9 (MMP-1/9) induced by UVB irradiation, were also effectively reduced by FA-HA. Additionally, FA-HA treatment decreases the phosphorylation of mitogen-activated protein kinase (MAPK) and activator protein-1 (AP-1), ultimately preventing apoptosis. These findings suggest that FA-HA is a promising candidate for UVB protection in skincare formulations.

In Silico Strategies to Predict Anti-aging Features of Whey Peptides

We have analysed the in silico potential of bioactive peptides from cheese whey, the most relevant by-product from the dairy industry, to bind into the active site of collagenase and elastase. The peptides generated from the hydrolysis of bovine β-lactoglobulin with three proteases (trypsin, chymotrypsin, and subtilisin) were docked onto collagenase and elastase by molecular docking. The interaction models were ranked according to their free binding energy using molecular dynamics simulations, which showed that most complexes presented favourable interactions. Interactions with elastase had significantly lower binding energies than those with collagenase. Regarding the interaction site, it was found that four bioactive peptides were positioned in collagenase's active site, while six were found in elastase's active site. Among these, the most we have found one promising collagen-binding peptide produced by chymotrypsin and two for elastase, produced by subtilisin and chymotrypsin. These in silico results can be used as a tool for designing further experiments aiming at testing the in vitro potential of the peptides found in this work.

γ-Mangosteen, an autophagy enhancer, prevents skin-aging via activating KEAP1/NRF2 signaling and downregulating MAPKs/AP-1/NF-κB-mediated MMPs

BACKGROUND

Mangosteens, a naturally occurring xanthones, found abundantly in mangosteen fruits. The anti-skin aging potential of γ-mangosteen (GM) remains unexplored; therefore, we investigated the UVB-induced anti-skin aging of GM via activation of autophagy.

HYPOTHESIS

We hypothesized that GM exerts antioxidant and anti-aging capabilities both in vitro and in vivo through activation of autophagy as well as control of KEAP1/NRF2 signaling and MAPKs/AP-1/NF-κB-mediated MMPs pathways.

METHODS

The anti-skin aging effects of GM were studied using HDF cells and a mice model. Various assays, such as DPPH, ABTS, CUPRAC, FRAP, and ROS generation, assessed antioxidant activities. Kits measured antioxidant enzymes, SA-β-gal staining, collagen, MDA content, si-RNA experiments, and promoter assays. Western blotting evaluated protein levels of c-Jun, c-Fos, p-IκBα/β, p-NF-κB, MAPK, MMPs, collagenase, elastin, KEAP1, NRF2, HO-1, and autophagy-related proteins.

RESULTS

GM exhibited strong antioxidant, collagenase and elastase enzyme inhibition activity surpassing α- and β-mangosteen. GM competitively inhibited elastase with a Ki value of 29.04 µM. GM orchestrated the KEAP1-NRF2 pathway, enhancing HO-1 expression, and suppressed UVB-induced ROS in HDF cells. NRF2 knockdown compromised GM's antioxidant efficacy, leading to uncontrolled ROS post-UVB. GM bolstered endogenous antioxidants, curbing lipid peroxidation in UVB-exposed HDF cells and BALB/c mice. GM effectively halted UVB-induced cell senescence, and reduced MMP-1/-9, while elevated TIMP-1 levels, augmented COL1A1, ELN, and HAS-2 expression in vitro and in vivo. Additionally, it suppressed UVB-induced MAPKs, AP-1, NF-κB phosphorylation. Pharmacological inhibitors synergistically enhanced GM's anti-skin aging potential. Moreover, GM inhibited UVB-induced mTOR activation, upregulated LC3-II, Atg5, Beclin 1, and reduced p62 in both UVB induced HDF cells and BALB/c mice, while blocking of autophagy successfully halt the GM effects against the UVB-induced increase of cell senescence, degradation of collagen through upregulation of MMP-1, underscoring GM's substantial anti-skin aging impact via autophagy induction in vitro and in vivo.

CONCLUSION

Together, GM has potent antioxidant and anti-skin aging ingredients that can be used to formulate skin care products for both the nutraceutical and cosmeceutical industries.

Marine Antioxidants from Marine Collagen and Collagen Peptides with Nutraceuticals Applications: A Review

Collagen peptides and marine collagen are enormous resources currently utilized. This review aims to examine the scientific literature to determine which collagen peptides derived from marine sources and which natural active antioxidants from marine collagen have significant biological effects as health-promoting nutraceuticals. Marine collagen is extracted from both vertebrate and invertebrate marine creatures. For vertebrates, this includes fish skin, bones, scales, fins, and cartilage. For invertebrates, it includes mollusks, echinoderms, crustaceans, and poriferans. The method used involved data analysis to organize information for isolating and identifying marine biocompounds with antioxidant properties. Specifically, amino acids with antioxidant properties were identified, enabling the use of hydrolysates and collagen peptides as natural antioxidant nutraceuticals. The methods of extraction of hydrolyzed collagen and collagen peptides by different treatments are systematized. The structural characteristics of collagen, collagen peptides, and amino acids in fish skin and by-products, as well as in invertebrate organisms (jellyfish, mollusks, and crustaceans), are described. The antioxidant properties of different methods of collagen hydrolysates and collagen peptides are systematized, and the results are comparatively analyzed. Their use as natural antioxidant nutraceuticals expands the range of possibilities for the exploitation of natural resources that have not been widely used until now.

Effects of collagen hydrolysates on UV-induced photoaging mice: Gly-Pro-Hyp as a potent anti-photoaging peptide

This work aimed to investigate the protective effects of collagen hydrolysates containing different contents of Gly-Pro-Xaa tripeptides on UV-induced photoaging mice and to identify potent anti-photoaging peptides. Results showed that oral ingestion of collagen hydrolysates with a higher content of Gly-Pro-Xaa tripeptides (∼11.4%, HCH) dramatically enhanced the absorption of Pro-Hyp, Hyp-Gly, and Gly-Pro-Hyp into the body, which were 1.77-, 2.18-, and 65.07-fold higher in area under the concentration-time curve (AUC) values than that of collagen hydrolysates with a lower content of Gly-Pro-Xaa tripeptides (∼3.8%, LCH), respectively. Furthermore, the protective effects of HCH on the photo-aged skin of mice were significantly stronger than those of LCH in terms of increases in the contents of hyaluronic acid and collagen, improvement in skin elasticity and epidermal thickness, alleviation in inflammation, and decreases in the contents of matrix metalloproteinase-1 (MMP-1) and MMP-3. More importantly, Gly-Pro-Hyp displayed potent anti-photoaging activities comparable to HCH based on an equivalent amount of Hyp. Network pharmacology analysis for potential mechanisms further indicated that Gly-Pro-Hyp might interact with JUN and FOS and regulate IL-17 and TNF signaling pathways. Collectively, our results suggested that HCH had great potential to be applied in functional foods for skin health and Gly-Pro-Hyp was found to be a potent collagen-derived anti-photoaging peptide, which might contribute to the excellent anti-photoaging effects of HCH.

Oral intake of collagen hydrolysate from mackerel scad (Decapterus macarellus) attenuates skin photoaging by suppressing the UVB-induced expression of MMP-1 and IL-6

OBJECTIVES

Excessive skin exposure to UVB radiation can induce photoaging caused by an imbalance in oxidative stress and inflammatory responses, damaging the skin's structure and surface layer. A previous study revealed that collagen hydrolisate extracted from the skin of mackarel scads (Decapterus macarellus) had antiaging properties that were tested in vitro, which serves as a foundation for a subsequent study of its use in vivo. This study aimed at investigating the repair effect of the mackerel scad's skin collagen hydrolysate (MSS-CH) in photoaging conditions in a mouse model.

METHODS

MSS-CH was given orally in mice model of skin photoaging under chronic exposure to UVB irradiation for 12 weeks. Morphological and histological changes on the skin were evaluated using SEM and HE staining, along with the measurement of the expression of matrix metalloproteinases (MMP-1) and cytokine pro-inflammatory interleukin 6 (IL-6) using ELISA.

RESULTS

MSS-CH inhibits the occurrence of epidermal thickening and damage to the dermal layer of the skin. As a result, it restores the epidermis' barrier function and reduces surface damage caused by photoaging. The skin of the MSS-CH treated group exhibited improved physical appearance with reduced fine lines, wrinkles, and enhanced smoothness. Additionally, administering MSS-CH to the mice groups reduced the expression of MMP-1 and IL-6 in UVB-exposed skin.

CONCLUSIONS

Altogether, this in vivo study demonstrates the photoaging-protective properties of CH-MSS, aligning with previous in vitro data. Thus, MSS-CH emerges as a strong candidate for use as an ingredient in nutraceuticals and biocosmetics.

Marine Bioactive Peptides: Anti-Photoaging Mechanisms and Potential Skin Protective Effects

Skin photoaging, resulting from prolonged exposure to ultraviolet radiation, is a form of exogenous aging that not only impacts the aesthetic aspect of the skin but also exhibits a strong correlation with the onset of skin cancer. Nonetheless, the safety profile of non-natural anti-photoaging medications and the underlying physiological alterations during the process of photoaging remain inadequately elucidated. Consequently, there exists a pressing necessity to devise more secure interventions involving anti-photoaging drugs. Multiple studies have demonstrated the noteworthy significance of marine biomolecules in addressing safety concerns related to anti-photoaging and safeguarding the skin. Notably, bioactive peptides have gained considerable attention in anti-photoaging research due to their capacity to mitigate the physiological alterations associated with photoaging, including oxidative stress; inflammatory response; the abnormal expression of matrix metalloproteinase, hyaluronidase, and elastase; and excessive melanin synthesis. This review provides a systematic description of the research progress on the anti-photoaging and skin protection mechanism of marine bioactive peptides. The focus is on the utilization of marine bioactive peptides as anti-photoaging agents, aiming to offer theoretical references for the development of novel anti-photoaging drugs and methodologies. Additionally, the future prospects of anti-aging drugs are discussed, providing an initial reference for further research in this field.

A review on the processing of functional proteins or peptides derived from fish by-products and their industrial applications

To understand the production and characteristics of protein hydrolysates pertaining to individual fish species, we selected and analyzed the most important commercial fish species according to the market value based on the Statistics on International Exports of Fishery Commodities by Food and Agriculture Organization. Accordingly, salmon, shrimp, cod, tuna, squid, and herring are marine species with high global value. Peptides obtained from their by-products were predominant in hydrophobic amino acids such as alanine, phenylalanine, methionine, proline, valine, tyrosine, tryptophan, leucine, and isoleucine. Bioactive peptides are short with a length of 2-20 amino acids. They remain inactive when they are within their parent proteins. Low molecular weight (0.3-8 kDa) peptides from hydrolyzed protein are easily digestible, readily absorbed by the body and are water-soluble. The hydrophobic nature contributes to their bioactivity, which facilitates their interactions with the membrane lipid bilayers. Incomplete hydrolysis results in low yields of hydrophobic amino acids. The glycosylation type of the resulting peptide fragment determines the different applications of the hydrolysate. The degree of conservation of the glycosidic residues and the size of the peptides are influenced by the method used to generate these hydrolysates. Therefore, it is crucial to explore inexpensive novel methodologies to generate bioactive peptides. According to the current studies, a unified approach (in silico estimation coupled with peptidomics) can be used for the identification of novel peptides with diverse physiological and technological functions. From an industrial perspective, the reusability of immobilized enzymes and membrane separation techniques (e.g., ultrafiltration) on marine by-products can offer low operating costs and higher yield for large-scale production of bioactive peptides. This review summarizes the production processes and essential characteristics of protein hydrolysates from fish by-products and presents the advances in their application.

The Anti-Photoaging Activity of Peptides from Pinctada martensii Meat

Long-term exposure to ultraviolet-B (UVB) can cause photoaging. Peptides from Pinctada martensii meat have been shown to have anti-photoaging activities, but their mechanism of action is rarely studied. In this study, Pinctada martensii meat hydrolysates (PME) were prepared by digestive enzymes and then separated by ultrafiltration and Sephadex G-25 gel filtration chromatography to obtain a purified fraction (G2). The fraction G2 was identified by ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), and peptide sequences were synthesized by solid-phase synthesis. The mechanism of anti-photoaging activities was investigated using a human immortalised epidermal (HaCaT) cell model. Results showed that peptides from Pinctada martensii meat increased UVB-induced cell viability and reduced the contents of interstitial collagenase (MMP-1) and matrix lysing enzyme (MMP-3) in HaCaT cells. Furthermore, the fraction of G2 significantly downregulated the expression of p38, EKR, JNK, MMP-1, and MMP-3 in HaCaT cells. The peptide sequences Phe-His (FH), Ala-Leu (AL), Met-Tyr (MY), Ala-Gly-Phe (AGF), and Ile-Tyr-Pro (IYP) were identified and synthesized. Besides, FH reduced the contents of MMP-1 and MMP-3 in HaCaT cells, combining them effectively in molecular docking analysis. Thus, peptides from Pinctada martensii meat showed anti-photoaging activities and might have the potential to be used as an anti-photoaging agent in functional foods.

Cosmeceutical Potential of Extracts Derived from Fishery Industry Residues: Sardine Wastes and Codfish Frames

The fishery industry generates large amounts of waste (20–75% (w/w) of the total caught fish weight). The recovery of bioactive compounds from residues and their incorporation in cosmetics represents a promising market opportunity and may contribute to a sustainable valorisation of the sector. In this work, protein-rich extracts obtained by high-pressure technologies (supercritical CO₂ and subcritical water) from sardine (Sardina pilchardus) waste and codfish (Gadus morhua) frames were characterized regarding their cosmeceutical potential. Antioxidant, anti-inflammatory and antibacterial activities were evaluated through chemical (ORAC assay), enzymatic (inhibition of elastase and tyrosinase), antimicrobial susceptibility (Klebsiella pneumoniae, Staphylococcus aureus and Cutibacterium acnes) and cell-based (in keratinocytes-HaCaT) assays. Sardine extracts presented the highest antibacterial activity, and the extract obtained using higher extraction temperatures (250 °C) and without the defatting step demonstrated the lowest minimum inhibitory concentration (MIC) values (1.17; 4.6; 0.59 mg/mL for K. pneumoniae, S. aureus and C. acnes, respectively). Codfish samples extracted at lower temperatures (90 °C) were the most effective anti-inflammatory agents (a concentration of 0.75 mg/mL reduced IL-8 and IL-6 levels by 58% and 47%, respectively, relative to the positive control). Threonine, valine, leucine, arginine and total protein content in the extracts were highlighted to present a high correlation with the reported bioactivities (R² ≥ 0.7). These results support the potential application of extracts obtained from fishery industry wastes in cosmeceutical products with bioactive activities.

Effects of Collagen Hydrolysate From Large Hybrid Sturgeon on Mitigating Ultraviolet B-Induced Photodamage

Ultraviolet B (UVB) radiation leads to the excessive accumulation of reactive oxygen species (ROS), which subsequently promote inflammation, degradation of the extracellular matrix, and photoaging in skin. Thus antioxidant activity is particularly important when screening for active substances to prevent or repair photodamage. Marine fish-derived bioactive peptides have become a trend in cosmetics and functional food industries owing to their potential dermatological benefits. In this study, 1-diphenyl- 2-pycryl-hydrazyl (DPPH) scavenging activity was selected to optimize the hydrolysis conditions of sturgeon skin collagen peptides with antioxidant activity. The optimal hydrolysis conditions for sturgeon skin collagen hydrolysate (SSCH) were determined by response surface methodology, which comprised an enzyme dosage of flavorzyme at 6,068.4 U/g, temperature of 35.5°C, pH of 7, and hydrolysis time of 6 h. SSCH showed good radical-scavenging capacities with a DPPH scavenging efficiency of 95%. Then, the effect of low-molecular-weight SSCH fraction (SSCH-L) on UVB irradiation-induced photodamage was evaluated in mouse fibroblast L929 cells and zebrafish. SSCH-L reduced intracellular ROS levels and the malondialdehyde content, thereby alleviating the oxidative damage caused by UVB radiation. Moreover SSCH-L inhibited the mRNA expression of genes encoding the pro-inflammatory cytokines IL-1β, IL-6, TNF-α, and Cox-2. SSCH-L treatment further increased the collagen Ⅰα1 content and had a significant inhibitory effect on matrix metalloproteinase expression. The phosphorylation level of JNK and the expression of c-Jun protein were significantly reduced by SSCH-L. Additionally, SSCH-L increased the tail fin area at 0.125 and 0.25 mg/ml in a zebrafish UVB radiation model, which highlighted the potential of SSCH-L to repair UVB-irradiated zebrafish skin damage. Peptide sequences of SSCH-L were identified by liquid chromatography-tandem mass spectrometry. Based on the 3D-QSAR modeling prediction, six total peptides were selected to test the UVB-protective activity. Among these peptides, DPFRHY showed good UVB-repair activity, ROS-scavenging activity, DNA damage-protective activity and apoptosis inhibition activity. These results suggested that DPFRHY has potential applications as a natural anti-photodamage material in cosmetic and functional food industries.

Preparation and Evaluation of Liposomes and Niosomes Containing Total Ginsenosides for Anti-Photoaging Therapy

Ginsenosides are the principal bioactive compounds of ginseng. Total ginsenosides (GS) contain a variety of saponin monomers, which have potent anti-photoaging activity and improve the skin barrier function. To enhance the efficiency of GS transdermal absorption, GS liposomes (GSLs) and GS niosomes (GSNs) were formulated as delivery vehicles. Based on the clarified and optimized formulation process, GSL and GSN were prepared. The structure, cumulative transmittance, skin retention, total transmittance, and bioactivity of GSLs and GSNs were characterized. GSL and GSN were shown to inhibit lipid peroxidation and increase the contents of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in human keratinocytes (HaCaTs). In addition, HaCAT cell migration, proliferation, and GS cellular uptake were significantly increased. The therapeutic effects of GSL and GSN were also evaluated in a rat model of photoaging. Histopathological changes were assessed in rat skin treated with GSL, GSN, or GS by hematoxylin–eosin (H&E) and aldehyde fuchsine staining. Malondialdehyde (MDA), SOD, GSH-Px, matrix metalloproteinases (MMPs), interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) expression levels were determined. Results indicated that the optimal formulation of GSL used soybean lecithin (SPC) as the phospholipid, with a lipid–drug ratio of 1:0.4 and a phospholipid–cholesterol ratio of 1:3.5. The optimal temperature for the preparation process of GSN by ethanol injection was 65°C, with a ratio of the organic phase to aqueous phase of 1:9. It was demonstrated that the cumulative release rate, skin retention rate, and total transmission rate of GSL-7 at 24 h were higher than those of GSN-4 and GS. GSL-7 significantly inhibited skin lipid peroxidation caused by ultraviolet (UV) radiation. In addition, GSL-7 reduced the contents of MMPs and inflammatory cytokines in skin tissue. In conclusion, GSL-7 may reduce skin aging caused by UV radiation and contribute to skin tissue repair.

Theragra chalcogramma Hydrolysate, Rich in Gly-Leu-Pro-Ser-Tyr-Thr, Alleviates Photoaging via Modulating Deposition of Collagen Fibers and Restoration of Extracellular Components Matrix in SD Rats

Excessive exposure of the skin to ultraviolet irradiation induces skin photoaging, which seriously deteriorates the barrier functions of skin tissue, and even causes skin damages and diseases. Recently, dietary supplements from marine sources have been found to be useful in modulating skin functions and can be used to alleviate photoaging. Herein, the low-molecular-weight hydrolysates with a photoaging-protection effect were prepared by enzymatic hydrolysis from Theragra chalcogramma (TCH), and the potential mechanism were subsequently explored. The results revealed that TCH desirably improved the barrier functions of photoaged skin and stimulated the deposition of ECM components Col I, Hyp, and HA in the dermal layer. Histologically, TCH reduced the epidermal hyperplasia and restored the impaired architectures in a dose-dependent manner. Meanwhile, the activity of matrix metalloproteinase-1 (MMP-1) in photoaging skin was inhibited, and the expression levels of elastin and fibrillin-1 were elevated accordingly after TCH administration, and the significant improvements were observed at high-dose level (p < 0.05). Taken together, the efficacy of TCH against skin photoaging is highly associated with the regulation on ECM metabolism and the repairing of damaged mechanical structure.

Attenuation of UV-induced skin photoaging in rats by walnut protein hydrolysates is linked to the modulation of MAPK/AP-1 and TGF-β/Smad signaling pathways

There is growing evidence that prevention of skin photoaging by oral administration of food-derived proteins hydrolysates is intricately linked to its alleviation against oxidative stress through modulation of the signaling pathway. Previously, walnut protein hydrolysates (WPHs) were prepared by enzymatic hydrolysis by our group and exhibited excellent anti-photoaging effect through regulation of extracellular matrix metabolism and the NF-κB signaling pathway. However, its response to oxidative stress and cascade mechanism remain unknown. In the present study, Sprague-Dawley rats were exposed periodically to UV irradiation and orally administered with WPHs to further examine the effects of WPHs on the redox state, MAPK/AP-1 and TGF-β/Smad signaling pathways, type I procollagen synthesis, and histopathological impairments in photoaging skin. Intervention with WPHs for 18 weeks significantly alleviated the photoaging morphology, enhanced the antioxidant components, and downregulated the phosphorylation levels of extracellular signal-regulated kinase (ERK) and C-Jun N-terminal kinase (JNK and p38 proteins) in photoaging tissues, while significant alterations on the gene expression levels of ERK, JNK and p38 were not observed. Meanwhile, WPHs significantly activated the TGF-β/Smad signaling pathway and type I procollagen production. Furthermore, histopathological analysis illustrated that WPHs predominately attenuated epidermal hyperplasia, reduced inflammatory filtration, and promoted the deposition of collagen fibers in photoaging skin. Altogether, the underlying mechanism of WPHs attenuating skin photoaging might lie in the synergistic modulation by increasing the antioxidant capacity, modulating the MAPK/AP-1/MMP-1 and TGF-β/Smad signaling pathways, stimulating the synthesis of type I procollagen, and restoring the impaired architecture structure. Our findings suggest that WPHs are promising agents for preventing skin photoaging.

Fish Waste: From Problem to Valuable Resource

Following the growth of the global population and the subsequent rapid increase in urbanization and industrialization, the fisheries and aquaculture production has seen a massive increase driven mainly by the development of fishing technologies. Accordingly, a remarkable increase in the amount of fish waste has been produced around the world; it has been estimated that about two-thirds of the total amount of fish is discarded as waste, creating huge economic and environmental concerns. For this reason, the disposal and recycling of these wastes has become a key issue to be resolved. With the growing attention of the circular economy, the exploitation of underused or discarded marine material can represent a sustainable strategy for the realization of a circular bioeconomy, with the production of materials with high added value. In this study, we underline the enormous role that fish waste can have in the socio-economic sector. This review presents the different compounds with high commercial value obtained by fish byproducts, including collagen, enzymes, and bioactive peptides, and lists their possible applications in different fields.

Walnut protein hydrolysates, rich with peptide fragments of WSREEQEREE and ADIYTEEAGR ameliorate UV-induced photoaging through inhibition of the NF-κB/MMP-1 signaling pathway in female rats

Skin photoaging is a complicated pathological process, and the imbalance of inflammatory regulation is associated highly with photoaging progression. Previously, prepared walnut protein hydrolysates (WPH), rich with peptide fragments of WSREEQEREE and ADIYTEEAGR demonstrated desirable photoprotection. However, it remains unclear if the photoprotection is mediated by the targeted inhibition of the NF-κB signaling pathway. Herein, we examined the regulation of WPH on inflammatory cytokine expression, and elucidated the modulation of the NF-κB/MMP-1 signaling pathway by WPH in a photoaging SD rat model. WPH significantly reduced the expression level of inflammatory cytokines IL-1β and IL-6, but significantly increased the level of IL-2 (all P < 0.05). Furthermore, WPH dramatically inhibited the activation of the NF-κB signaling pathway by mitigating the phosphorylation of IκB and p-65 proteins in a dose-dependent manner. The histopathological results indicated that WPH predominately attenuated epidermal hyperplasia, reduced the inflammatory filtration, and promoted collagen deposition in the photoaging skin tissue. Furthermore, WPH significantly stimulated the expression of TGF-β and procollagen type I, and inhibited the MMP-1 activities (all P < 0.05). Overall, the underlying mechanism of WPH ameliorating skin photoaging may be attributed to the synergistic modulation via reversing the inflammatory imbalance, suppressing the activation of the NF-κB signal pathway, stimulating procollagen type I synthesis, and inhibiting MMP-1 activities. According to these results, it can be concluded that WPH has the potential as an anti-photoaging agent in functional foods.

Diet and Skin Aging-From the Perspective of Food Nutrition

We regularly face primary challenges in deciding what to eat to maintain young and healthy skin, defining a healthy diet and the role of diet in aging. The topic that currently attracts maximum attention is ways to maintain healthy skin and delay skin aging. Skin is the primary barrier that protects the body from external aggressions. Skin aging is a complex biological process, categorized as chronological aging and photo-aging, and is affected by internal factors and external factors. With the rapid breakthrough of medicine in prolonging human life and the rapid deterioration of environmental conditions, it has become urgent to find safe and effective methods to treat skin aging. For diet, as the main way for the body to obtain energy and nutrients, people have gradually realized its importance to the skin. Therefore, in this review, we discuss the skin structure, aging manifestations, and possible mechanisms, summarize the research progress, challenges, possible directions of diet management, and effects of foodborne antioxidants on skin aging from the perspective of food and nutrition.

The protective effects of β-sitosterol and vermicularin from Thamnolia vermicularis (Sw.) Ach. against skin aging in vitro

Aged skin, featured with dryness and wrinkles, has received mounting attention due to its adverse influences on beauty. β-Sitosterol and vermicularin are two common active ingredients of Thamnolia vermicularis (Sw.) Ach., a traditional Chinese medicine, of which the anti-aging effect has been discovered. Their protective performance against skin aging was assayed by co-culturing with skin cells in this work. Results showed that β-sitosterol promoted the biosynthesis of hyaluronic acid by increasing the expression of hyaluronic acid synthases in fibroblasts and enhanced the expression of skin barrier functional proteins including aquaporin 3, loricrin, filaggrin and involucrin in keratinocytes, which conduced to the moisture retention within skin. Moreover, vermicularin might function as an anti-wrinkle agent by preventing the loss of collagen type I. Specifically, vermicularin reduced the amount of reactive oxygen species within hydrogen-peroxide-induced fibroblasts; together with suppressing the activation of mitogen-activated protein kinases, it could inhibit the production of matrix metalloproteinases-1. The present research will contribute to the development of the compounds as anti-aging ingredients for future applications in cosmetic formulations and functional food as well as promote further studies of raw materials containing alike compounds.

Potential role of natural bioactive peptides for development of cosmeceutical skin products

In recent years, consumers' demand for cosmeceutical products with protective and therapeutic functions derived from natural sources have caused this industry to search for alternative active ingredients. Bioactive peptides have a wide spectrum of bioactivities, which make them ideal candidates for development of these cosmeceutical products. In vitro studies have demonstrated that bioactive peptides (obtained as extracts, hydrolysates, and/or individual peptides) exhibit biological properties including antioxidant, antimicrobial, and anti-inflammatory activities, in addition to their properties of inhibiting aging-related enzymes such as elastase, collagenase, tyrosinase and hyaluronidase. Some studies report multifunctional bioactive peptides that can simultaneously affect, beneficially, multiple physiological pathways in the skin. Moreover, in vivo studies have revealed that topical application or consumption of bioactive peptides possess remarkable skin protection. These properties suggest that bioactive peptides may contribute in the improvement of skin health by providing specific physiological functions, even though the mechanisms underlying the protective effect have not been completely elucidated. This review provides an overview of in vitro, in silico and in vivo properties of bioactive peptides with potential use as functional ingredients in the cosmeceutical field. It also describes the possible mechanisms involved as well as opportunities and challenges associated with their application.

Gelatin and Antioxidant Peptides from Gelatin Hydrolysate of Skipjack Tuna (Katsuwonus pelamis) Scales: Preparation, Identification and Activity Evaluation

For full use of fish by-products, scale gelatin (TG) and antioxidant peptides (APs) of skipjack tuna (Katsuwonus pelamis) were prepared, and their properties were characterized using an amino acid analyzer, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FTIR), electrospray ionization mass spectrometers (ESI-MS), and radical scavenging assays. The results indicate that TG with a yield of 3.46 ± 0.27% contained Gly (327.9 ± 5.2 residues/1000 residues) as the major amino acid and its imino acid content was 196.1 residues/1000 residues. The structure of TG was more unstable than that of type I collagen from scales of skipjack tuna (TC) and TG was more suitable for preparation of hydrolysate by protease than mammalian gelatins. Therefore, TG was separately hydrolyzed under five proteases (pepsin, papain, trypsin, neutrase, and alcalase) and ten APs (TGP1–TGP10) were isolated from the alcalase-hydrolysate. Among them, TGP5, TGP7, and TGP9 with high antioxidant activity were identified as His-Gly-Pro-Hyp-Gly-Glu (TGP5), Asp-Gly-Pro-Lys-Gly-His (TGP7) and Met-Leu-Gly-Pro-Phe-Gly-Pro-Ser (TGP9), respectively. Furthermore, TGP5, TGP7, and TGP9 exhibited a high radical scavenging capability on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (EC₅₀ values of 1.34, 0.54, and 0.67 mg/mL, respectively), hydroxyl radical (EC₅₀ values of 1.03, 0.41, and 0.74 mg/mL, respectively), and superoxide anion radical (EC₅₀ values of 1.19, 0.71, and 1.59 mg/mL, respectively). These results suggest that three APs (TGP5, TGP7, and TGP9), especially TGP7, have a strong antioxidant activity and could act as potential antioxidant ingredients applied in functional products.

Effects of rambutan (Nephelium lappaceum) peel phenolics and Leu-Ser-Gly-Tyr-Gly-Pro on hairless mice skin photoaging induced by ultraviolet irradiation

Rambutan peel phenolics (RPP) have high antioxidant and anti-inflammatory activities. Leu-Ser-Gly-Tyr-Gly-Pro (LSGYGP) possesses good radical scavenging activity and matrix metalloproteinase (MMPs) inhibitory ability. These underlying mechanisms indicated that RPP and LSGYGP may be used for antiphotoaging. Few data on the effects of RPP and LSGYGP on in vivo photoaging are available. We evaluated the effects of RPP and/or LSGYGP on ultraviolet (UV)-induced hairless mice skin photoaging. In particular, we analyzed the additive effect of RPP and LSGYGP. The biochemical indices of mice skin, including composition (collagen and hyaluronic acid [HA] contents), oxidant stress (antioxidant enzyme activities and glutathione and malondialdehyde contents), MMPs (MMP-1, MMP-3, and MMP-9 levels), inflammatory cytokines (interleukin (IL)-1α, tumor nuclear factor-α, and IL-6 levels) and the phosphorylation of the mitogen-activated protein kinase pathway, were determined. Results showed a protective effect of RPP and/or LSGYGP on photoaging skin. LSGYGP showed considerable effects on skin collagen and HA contents. RPP showed improved effects on the regulation of the oxidant stress and inflammatory cytokine levels. RPP and LSGYGP exerted an additive effect on the amelioration of the biochemical indices of UV-induced photoaging skin. The histological changes showed that RPP and LSGYGP recovered the changes in skin tissue and endogenous collagen.

Preparation, structure identification and the anti-photoaging activity of peptide fraction OP-Ia from Ostrea rivularis

The purpose of the present study is to evaluate the preparation and the structure of fraction OP-Ia and its protective effect against UV-induced photoaging through the MAPKs signaling pathway. Fractions OP-Ia and OP-Ib were prepared by enzymatic hydrolysis and purified by ultrafiltration (5 kDa) and gel chromatography (Sephadex G-25). The reducing power and superoxide radical scavenging ability were evaluated, which showed that OP-Ia had stronger antioxidant activity than OP-Ib. Next, ten peptides were identified in OP-Ia by UPLC-MS/MS. The mechanism of the anti-photoaging activity for fraction OP-Ia was investigated through the MAPKs pathway based on the HaCaT cell line. Fraction OP-Ia could inhibit the generation of ROS and the decline of cell viability induced by UV radiation, meanwhile downregulate the expression of IL-1β, IL-8, c-Jun, c-Fos, p65 NF-κB and p38 MAPK genes. Overall, the results showed that the fraction OP-Ia could be a potent component of functional foods with UV protection property.

OP-Ia could reduce ROS generation and cell viability declination induced by UV, and downregulate the expressions of IL-1β, IL-8, c-Jun, c-Fos, p65 and p38 genes.

Regulation by walnut protein hydrolysate on the components and structural degradation of photoaged skin in SD rats

Skin photoaging induced by consecutive exposure of skin to ultraviolet radiation is primarily responsible for skin aging and preparation of food-derived ingredients with anti-aging functions has been the hot topic worldwide.

Hawthorn Polyphenol Extract Inhibits UVB-Induced Skin Photoaging by Regulating MMP Expression and Type I Procollagen Production in Mice

Ultraviolet (UV) B radiation can cause skin aging by increasing matrix metalloproteinase (MMP) production and collagen degradation, leading to the formation of wrinkles. This study investigated whether hawthorn polyphenol extract (HPE) protects against UVB-induced skin photoaging using HaCaT human keratinocytes, normal human dermal fibroblasts (HDFs), and mice. Analysis of the phenol composition of HPE by high-performance liquid chromatography-mass spectrometry showed that chlorogenic acid (13.5%), procyanidin B2 (19.2%), and epicatechin (18.8%) collectively accounted for 51.4% of total phenol content and represent the active ingredients of hawthorn fruit. A cell viability assay revealed that HPE treatment promoted cell proliferation in HaCaT cells and HDFs. On the other hand, MMP-1 and type I procollagen production was decreased and increased, respectively, in UVB-exposed cells treated with HPE as compared with those without treatment, as determined by enzyme-linked immunosorbent assay. Hematoxylin and eosin and Weigert staining of dermal tissue specimens from mice demonstrated that HPE also reversed UVB-induced epidermal thickening and dermal damage. The increase in production of reactive oxygen species and decrease in antioxidant enzyme activity as well as the increase in nuclear factor-κB activation and mitogen-activated protein kinase phosphorylation induced by UVB irradiation were reversed by HPE (100 or 300 mg/kg body weight), which also suppressed MMP expression and stimulated the production of type I procollagen in the dorsal skin of UVB-irradiated mice. These results suggest that HPE is a natural product that can prevent UVB radiation-induced skin photoaging.

Protective Effects of LSGYGP from Fish Skin Gelatin Hydrolysates on UVB-Induced MEFs by Regulation of Oxidative Stress and Matrix Metalloproteinase Activity

A previous study has shown that tilapia fish skin gelatin hydrolysates inhibited photoaging in vivo, and that, Leu-Ser-Gly-Tyr-Gly-Pro (LSGYGP) identified in the hydrolysate had a high hydroxyl radical scavenging activity. In this study, activities of LSGYGP were further evaluated using ultraviolet B (UVB)-induced mouse embryonic fibroblasts (MEFs). UVB irradiation significantly increased the intercellular reactive oxygen species (ROS) production and matrix metalloproteinases (MMPs) activities and decreased the content of collagen in MEFs. LSGYGP reduced the intercellular ROS generation in UVB-induced MEFs. Meanwhile, the decrease of superoxide dismutase (SOD) activity and the increase of malondiaidehyde (MDA) content were inhibited by LSGYGP. LSGYGP reduced MMP-1 and MMP-9 activities in a dose-dependent manner. Molecular docking simulation indicated that LSGYGP inhibited MMPs activities by docking the active sites of MMP-1 and MMP-9. Furthermore, LSGYGP also affected the intercellular phosphorylation of UVB-induced the mitogen-activated protein kinase pathway. LSGYGP could protect collagen synthesis in MEFs under UVB irradiation by inhibiting oxidative stress and regulating MMPs activities.

Purification and Characterization of Peptides Inhibiting MMP-1 Activity with C Terminate of Gly-Leu from Simulated Gastrointestinal Digestion Hydrolysates of Tilapia (Oreochromis niloticus) Skin Gelatin

Tilapia skin gelatin hydrolysates (TSGHs) were prepared by simulated gastrointestinal digestion and separated by gel filtration and semi-preparative reversed-phase high-performance liquid chromatography. The anti-photoaging effects were evaluated using an ultraviolet radiation B (UVB)-induced mouse embryonic fibroblast (MEF) photoaging model in vitro. Three fractions from TSGHs with high inhibitory intercellular matrix metalloproteinase-1 (MMP-1) activities and reactive oxygen species (ROS) production were obtained. Three key peptides, GYTGL, LGATGL, and VLGL, were identified, and their C terminate was Gly-Leu. Three peptides were synthesized and exhibited a significant inhibition of intercellular MMP-1 activity and ROS production. Furthermore, three peptides inhibiting MMP-1 activities were evaluated through their docking of S₁' and S₃' active pockets of MMP-1. Hydrogen bonds and C terminate Gly-Leu played important roles. Finally, the protective effects of three peptides on intercellular collagen in UVB-induced MEFs were compared. Our results indicated that tilapia gelatin peptides exhibited potential activities to prevent and regulate photoaging.

Neuroprotective Effects of Acetylcholinesterase Inhibitory Peptides from Anchovy (Coilia mystus) against Glutamate-Induced Toxicity in PC12 Cells

Ameliorations of cholinergic system dysfunction and oxidative stress in neurodegenerative diseases were main approaches to improve memory disorder. Our previous investigation showed that anchovy protein hydrolysate (APH) could attenuate scopolamine-induced memory deficits in mice by regulating acetylcholinesterase (AChE) activity. Therefore, peptides with AChE inhibitory activity in APH were explored and identified in this study, and their possible neuroprotective mechanisms on glutamate induced apoptosis in PC12 were also elucidated. Two peptides with strong AChE inhibitory capacity were identified as Pro-Ala-Tyr-Cys-Ser (PAYCS) and Cys-Val-Gly-Ser-Tyr (CVGSY) by ultraperformance liquid chromatography coupled with tandem mass spectrometry. The AChE inhibitory was 23.68 ± 0.97% and 6.08 ± 0.41%, respectively. Treatment with PAYCS and CVGSY could significantly (p < 0.05) increase cells viability, reduce lactate dehydrogenase release, reactive oxygen species (ROS) production, malondialdehyde content, and the ratio of Bax/Bcl-2 of glutamate-induced apoptosis PC12 cells (82.78 ± 6.58 and 109.94 ± 7.16% of control, respectively) as well as increase superoxide dismutase and GSH-px activities. In addition, both the peptides could inhibit Ca²⁺ influx but have no effects on mitochondrial membrane potential. Results indicated that AChE inhibitory peptides (PAYCS and CVGSY) possibly protected the PC12 cells against glutamate-induced apoptosis via inhibiting ROS production and Ca²⁺ influx. PAYCS and CVGSY might be considered as nutraceuticals for alleviating memory deficits.

Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium

Two novel calcium-chelating peptides have been identified from Pacific cod skin gelatin, and the binding mode of the two peptides with calcium has been elucidated.