Protective Effect of Bovine Elastin Peptides against Photoaging in Mice and Identification of Novel Antiphotoaging Peptides

Research Progress on New Functions of Animal and Plant Proteins

Protein is composed of peptides, essential nutrients for human survival and health, and the easy absorption of peptides further promotes human health. According to the source of the protein, it can be divided into plants, animals, and micro-organisms, which have important physiological effects on the health of the body, especially in enhancing immunity. The most widely used raw materials are animal protein and plant protein, and the protein composition formed by the two in a certain proportion is called "double protein". In recent years, China's State Administration for Market Regulation has issued an announcement on the "Implementation Rules for the Technical Evaluation of New Functions and Products of Health Foods (Trial)", which provides application conditions and listing protection for the research and development of new functions of health foods. At present, some researchers and enterprises have begun to pay attention to the potential of animal and plant proteins to be used in new functions. In this article, the research progress of animal and plant proteins in the new functions of Chinese health food is reviewed in detail, and suggestions for future research on animal and plant proteins are put forward.

Compound collagen peptide powder improves skin photoaging by reducing oxidative stress and activating TGF-β1/Smad pathway

Fish collagen peptide (FCP) has been extensively investigated as a natural product that can combat photoaging; however, its efficacy is limited by its singular composition. Compound collagen peptide powder (CCPP) is a novel functional food formulation that exhibits photoprotective properties and comprises FCP and a blend of natural botanical ingredients. The objective of this study was to investigate the efficacy of CCPP and its molecular mechanism. CCPP had a low molecular weight, facilitating its efficient absorption, and was abundant in amino acids, total polyphenols, and total flavonoids. The results of in vivo studies demonstrated that CCPP exhibited significant efficacy in reducing skin wrinkles, enhancing the contents of water and oil in the skin, and ameliorating histopathological alterations in mice. The results of in vitro studies demonstrated that CCPP effectively mitigated photoaging in human skin fibroblasts by attenuating oxidative stress and promoting extracellular matrix (ECM) synthesis. Moreover, we clearly demonstrated that the TGF β1/Smad pathway was involved in the promotion of ECM synthesis and cell proliferation by CCPP in human skin fibroblasts. These findings suggest that, compared with single collagen, CCPP has a more comprehensive range of antiphotoaging properties.

Oral consumption of Bonito fish-derived elastin peptide (VGPG Elastin® ) improves biophysical properties in aging skin: A randomized, double-blinded, placebo-controlled study

BACKGROUND

Recent in vitro and in vivo studies have suggested that the elastin peptide improves the skin's biophysical properties, enhancing the proliferation of fibroblasts and elastin synthesis, resulting in anti-aging properties. Therefore, we conducted a randomized, double-blinded, placebo-controlled study to clinically evaluate the effect of elastin peptide intake on human skin.

MATERIALS AND METHODS

Healthy adult participants (N = 100) were randomly assigned to receive a test product containing 100 mg of Bonito elastin peptide (VGPG Elastin® ) or placebo. In this study, all participants were Asian from Korea. The parameters of skin wrinkles, hydration, and brightening (melanin index) were measured at baseline and 4, 8, and 12 weeks after intervention.

RESULTS

The average skin roughness, maximum peak-to-valley values, maximum peak height of the wrinkle, maximum valley depth of the wrinkle, average maximum height of the wrinkle, and eye wrinkle volume improved considerably in the test group compared with the placebo after 12 weeks of intervention. Skin hydration was enhanced, and the melanin index was significantly lower in the test group than in the placebo group. No participant experienced adverse events related to the test product.

CONCLUSION

Oral consumption of Bonito elastin peptide (VGPG Elastin®) reduced fine wrinkles, enhanced skin moisture, and decreased melanin index without significant adverse effects and may be a promising anti-wrinkle, anti-dryness, and anti-pigmentation treatment.

Dietary supplementation with α-ionone alleviates chronic UVB exposure-induced skin photoaging in mice

Photoaging is widely regarded as the most significant contributor to skin aging damage. It is triggered by prolonged exposure to ultraviolet (UV) light and typically manifests as dryness and the formation of wrinkles. Nutritional intervention is a viable strategy for preventing and treating skin photoaging. In previous studies, we demonstrated that α-ionone had ameliorating effects on photoaging in both epidermal keratinocytes and dermal fibroblasts. Here, we investigated the potential anti-photoaging effects of dietary α-ionone using a UVB-irradiated male C57BL/6N mouse model. Our findings provided compelling evidence that dietary α-ionone alleviates wrinkle formation, skin dryness, and epidermal thickening in chronic UVB-exposed mice. α-Ionone accumulated in mouse skin after 14 weeks of dietary intake of α-ionone. α-Ionone increased collagen density and boosted the expression of collagen genes, while attenuating the UVB-induced increase of matrix metalloproteinase genes in the skin tissues. Furthermore, α-ionone suppressed the expression of senescence-associated secretory phenotypes and reduced the expression of the senescence marker p21 and DNA damage marker p53 in the skin of UVB-irradiated mice. Transcriptome sequencing results showed that α-ionone modifies gene expression profiles of skin. Multiple pathway enrichment analyses on both the differential genes and the entire genes revealed that α-ionone significantly affects multiple physiological processes and signaling pathways associated with skin health and diseases, of which the p53 signaling pathway may be the key signaling pathway. Taken together, our findings reveal that dietary α-ionone intervention holds promise in reducing the risks of skin photoaging, offering a potential strategy to address skin aging concerns.

Screening of novel bovine-elastin-derived peptides with elastase inhibition and photoprotective potential: a combined in silico and in vitro study

BACKGROUND

The demand for food-based anti-photoaging products is surging because of the rising recognition of health and beauty, as well as enhanced comprehension of the detrimental impact of ultraviolet (UV) radiation. This study aimed to investigate the potential of bioactive peptides derived from bovine elastin, specifically focusing on identifying novel elastase inhibitory peptides and assessing their photoprotective properties using bioinformatics techniques.

RESULTS

A total of 48 bioactive peptides were screened in bovine elastin hydrolysate (EH) utilizing Peptide Ranker analysis. Three novel elastase inhibitory peptides, GAGQPFPI, FFPGAG and FPGIG (in descending order of activity), exhibited potent inhibitory effects on elastase in vitro, surpassing the inhibitory effect of EH by a factor of 1-2 and reaching significantly lower concentrations (8-15 times lower) than EH. The cumulative inhibitory effect of GAGQPFPI, FFPGAG, and FPGIG reached 91.5%. Further analysis revealed that FFPGAG and FPGIG exhibited mixed inhibition, whereas GAGQPFPI displayed non-competitive inhibition. Molecular simulations showed that these peptides interacted effectively with the elastase active site through hydrogen bonding and hydrophobic interactions. Furthermore, GAGQPFPI, FFPGAG, and FPGIG demonstrated high stability in gastrointestinal digestion, demonstrated transcellular permeability across Caco-2 cell monolayers, and exhibited remarkable photoprotective properties against UVB-irradiated HaCaT cells.

CONCLUSION

GAGQPFPI showed the most promising potential as a functional food with photoprotective effects against UVB damage and inhibitory properties against elastase. © 2023 Society of Chemical Industry.

Exploring the Release of Elastin Peptides Generated from Enzymatic Hydrolysis of Bovine Elastin via Peptide Mapping

To enhance the understanding of enzymatic hydrolysis and to accelerate the discovery of key bioactive peptides within enzymatic products, this research focused on elastin as the substrate and investigated the variations in peptide profiles and the production of key bioactive peptides (those exceeding 5% of the total) and their impacts on the biological activity of the hydrolysates. Through the application of advanced analytical techniques, such as stop-flow two-dimensional liquid chromatography and ultra-high-performance liquid chromatography-tandem mass spectrometry, the research tracks the release and profiles of peptides within elastin hydrolysates (EHs). Despite uniform peptide compositions, significant disparities in peptide concentrations were detected across the hydrolysates, hinting at varying levels of bioactive efficacy. A comprehensive identification process pinpointed 403 peptides within the EHs, with 18 peptides surpassing 5% in theoretical maximum content, signaling their crucial role in the hydrolysate's bioactivity. Of particular interest, certain peptides containing sequences of alanine, valine, and glycine were released in higher quantities, suggesting Alcalase® 2.4L's preference for these residues. The analysis not only confirms the peptides' dose-responsive elastase inhibitory potential but also underscores the nuanced interplay between peptide content, biological function, and their collective synergy. The study sets the stage for future research aimed at refining enzymatic treatments to fully exploit the bioactive properties of elastin.

Food Peptides for the Nutricosmetic Industry

In recent years, numerous reports have described bioactive peptides (biopeptides)/hydrolysates produced from various food sources. Biopeptides are considered interesting for industrial application since they show numerous functional properties (e.g., anti-aging, antioxidant, anti-inflammatory, and antimicrobial properties) and technological properties (e.g., solubility, emulsifying, and foaming). Moreover, they have fewer side effects than synthetic drugs. Nevertheless, some challenges must be overcome before their administration via the oral route. The gastric, pancreatic, and small intestinal enzymes and acidic stomach conditions can affect their bioavailability and the levels that can reach the site of action. Some delivery systems have been studied to avoid these problems (e.g., microemulsions, liposomes, solid lipid particles). This paper summarizes the results of studies conducted on biopeptides isolated from plants, marine organisms, animals, and biowaste by-products, discusses their potential application in the nutricosmetic industry, and considers potential delivery systems that could maintain their bioactivity. Our results show that food peptides are environmentally sustainable products that can be used as antioxidant, antimicrobial, anti-aging, and anti-inflammatory agents in nutricosmetic formulations. Biopeptide production from biowaste requires expertise in analytical procedures and good manufacturing practice. It is hoped that new analytical procedures can be developed to simplify large-scale production and that the authorities adopt and regulate use of appropriate testing standards to guarantee the population's safety.

Challenges and strategies for collagen delivery for tissue regeneration

Background: Aged skin is characterized by wrinkles, hyperpigmentation, and roughness. Collagen is the most abundant protein in our body and it’s responsible for skin health and it’s mostly influenced by factors that accelerated aging such as UV. Objective: This study aimed to identify the potential use of collagen as skin supplementation and the challenges and strategies for its delivery. Methods: The articles were first searched through the existing database with the keyword of “collagen antiaging”. The 585 articles were then screened by year of publication (2012-2022) resulted in 475 articles. The articles were then selected based on the delivery of collagen either orally or topically, resulted in 12 articles for further analysis. Results: Collagen has important roles in skin physiology by involving some mechanisms through inhibition of Mitogen-Activated Protein Kinase, induction of Tissue Growth Factor β (TGF-β), and inhibition of Nuclear Factor kappa beta (NF-κβ). The oral administration of collagen has an effective biological activity but requires large doses (up to 5 g daily). Meanwhile, the topical administration of collagen is limited by poor permeability due to high molecular weight (±300 kDa). Several strategies need to be carried out mainly by physical modification such as hydrolyzed collagen or entrapment of collagen using a suitable delivery system. Conclusions: Collagen could improve the skin properties, but further research should be conducted to increase its penetration either by physical modification or entrapment into suitable carrier.

Resource Utilization of Bovine Neck Ligament: Enzymatic Preparation of Elastin Peptide and Its Antioxidant Activity

Elastin is considered an excellent resource for obtaining antioxidant peptides due to unique amino acid composition. However, it is hardly soluble in water or in dilute acid or alkali; most of the elastases have low yields for preparing elastin peptides, making it difficult to meet industrial applications. To address above problems, enzymes capable of hydrolyzing elastin into soluble peptides were preferred from typical commercial protease preparations. The optimal enzymatic hydrolysis process conditions for elastin peptides were obtained by response surface optimization design. The molecular weight, amino acid composition, and antioxidant activity of the enzymatic hydrolysis products were determined. The results show that the alkaline protease NUE has a strong hydrolysis effect. The optimized enzymatic hydrolysis conditions are as follows: substrate concentration is 5%, enzyme concentration is 650 U/mL, pH is 10.0, temperature is 60 °C, time is 6 h. The degree of hydrolysis of elastic protein peptides obtained through this method is 14.42%. The distribution of molecular weight is 200-6500 Da, more than 85% of the component molecular amount is greater than 800 Da; the amino acid content related to antioxidant activity has reached 68 mg/100 mg, so it has extremely high free radical clearance. Compared with acid and alkali methods, the anti-oxidation capacity of enzyme-based peptide is better, the reaction conditions are milder, the yield is higher, and by-products and pollutants are fewer. It provides an effective way to industrialized production of elastin peptides with high antioxidant activity and a basis for its widespread application in the food and pharmaceutical industries.

Preparation, identification, and molecular docking of novel elastase inhibitory peptide from walnut (Juglans regia L.) meal

This study aimed to isolate bioactive peptides with elastase inhibitory activity from walnut meal via ultrasonic enzymatic hydrolysis. The optimal hydrolysis conditions of walnut meal protein hydrolysates (WMPHs) were obtained by response surface methodology (RSM), while a molecular weight of<3 kDa fraction was analyzed by LC-MS/MS, and 556 peptides were identified. PyRx virtual screening and Autodock Vina molecular docking revealed that the pentapeptide Phe-Phe-Val-Pro-Phe (FFVPF) could interact with elastase primarily through hydrophobic interactions, hydrogen bonds, and π-sulfur bonds, with a binding energy of -5.22 kcal/mol. The verification results of inhibitory activity showed that FFVPF had better elastase inhibitory activity, with IC₅₀ values of 0.469 ± 0.01 mg/mL. Furthermore, FFVPF exhibited specific stability in the gastric environment. These findings suggest that the pentapeptide FFVPF from defatted walnut meal could serve as a potential source of elastase inhibitors in the food, medical, and cosmetics industries.

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.

Preparation, Sensory Characterization, and Umami-Enhancing Mechanism of Novel Peptide Glycoconjugates

Previous studies supposed that Amadori rearrangement products (ARPs) of peptides might have better umami-enhancing abilities. To confirm this, five ARPs (EP-ARP, AH-ARP, EE-ARP, β-AH-ARP, RFPHADF-ARP) were synthesized using a food-grade preparation method, and their chemical structures were clearly demonstrated by mass spectrometry and 1D/2D NMR. Sensory experiments showed that ARPs had better umami-enhancing abilities than the corresponding peptides in this research, though their enhancing performance varied. ARPs showed a synergistic effect with multiple umami substances (MSG and GMP), while their corresponding peptides did not. RFPHADF-ARP had good umami-enhancing capacity, despite that RFPHADF was a bitter peptide without any umami/umami-enhancing property. RFPHADF-ARP could bind to the T1R3, which is beneficial to the stability of the active conformation of the umami receptor. The introduction of glucose via the Maillard reaction increased the binding force of RFPHADF with the umami receptor by influencing the electron density distribution and offering more binding groups (hydroxide group).

Photoprotective effects of sweet potato leaf polyphenols and caffeic acid against UV-induced skin-damage in BALB/C nude mice

This study aimed at clarifying the mechanism by which sweet potato leaf polyphenols (SPLPs) ameliorate ultraviolet (UV) radiation damage, using the BALB/c hairless female mouse model. The moisture and hydroxyproline (HYP) contents of the model mouse skin and the thickness of the epidermis and dermis were determined by staining and histological examination. Anti-oxidative enzyme activities, malondialdehyde (MDA) content, and protein carbonyl content in skin tissue and serum were investigated. Expression of inflammatory markers and mitogen-activated protein kinase signaling pathways were evaluated. Topical caffeic acid at 30 mg kg^-1 most strongly inhibited the decrease in skin moisture, HYP content, and the thickening of the epidermis. Topical SPLP at 100 mg kg^-1 most significantly inhibited the dermal thickening, increased the activities of the superoxide dismutase, catalase as well as glutathione peroxidase, and decreased the content of serum MDA and protein carbonyls markedly. Furthermore, the topical SPLP suppressed the UV-induced rise in the inflammatory markers MMP-1, TNF-α, and NF-κB, and alleviated phosphorylation levels of the stress-signaling proteins JNK and p38. Thus, topical SPLP provided the best overall protection for mouse skin from UV-induced damage.

Structure-Activity Relationship of Pine Nut-Derived Peptides and Their Protective Effect on Nerve-Cell Mitochondria

This study aimed to investigate the structure-activity relationship of the pine nut antioxidant peptide WYPGK and its derivative peptides, and to evaluate the protective effect of the latter on oxidative damage to mitochondrial structure and function in PC12 cells. Molecular docking revealed the derivative peptides WYFGK and WYSGK to have higher affinity to the active region of sirtuin 3 (SIRT3) (−6.08 kcal/mol and −5.87 kcal/mol, respectively), hence indicating that they are promising SIRT3 inducers and antioxidant factors. The derivative peptide WYSGK presented the highest ORAC value (5457.70 µmol TE/g), ABTS scavenging activity (70.05%), and Fe2+-chelating activity (81.70%), followed by WYPGK and WYFGK. Circular dichroism and nuclear magnetic resonance data suggested that the presence of 3-Ser in WYSGK increased its β-sheet content, and that the active hydrogen atoms produced chemical shifts. In H2O2-induced PC12 cells, WYSGK substantially reduced ROS and MDA levels, and increased ATP levels. Transmission electron microscopy and Seahorse Analyze assay proved the peptide WYSGK to significantly alleviate mitochondrial damage and respiratory dysfunction (p < 0.05), thereby implying that a study of structure-activity relationships of the peptides can possibly be an effective approach for the development of functional factors.

Theragra chalcogramma Hydrolysates, Rich in Gly-Leu-Pro-Ser-Tyr-Thr, Exerts Anti-Photoaging Potential via Targeting MAPK and NF-κB Pathways in SD Rats

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.

Oral Intake of Chicken Bone Collagen Peptides Anti-Skin Aging in Mice by Regulating Collagen Degradation and Synthesis, Inhibiting Inflammation and Activating Lysosomes

The effect of diet on skin aging has become an interesting research topic. Previous studies have mostly focused on the beneficial effects of collagen peptides derived from marine organisms on the aging skin when administered orally, while the beneficial effects of collagen peptides derived from poultry on aging skin have been rarely reported. In this study, collagen peptides were prepared from chicken bone by enzymatic hydrolysis, and the effect and mechanism of action of orally administered collagen peptides on alleviating skin aging induced by UV combined with D-galactose were investigated. The results showed that the chicken bone collagen had typical characteristics of collagen, and the chicken bone collagen peptides (CPs) were mainly small molecular peptides with a molecular weight of <3000 Da. In vivo experiments showed that CPs had a significant relieving effect on aging skin, indicated by the changes in the compostion and structure of the aging skin, improvement of skin antioxidant level, and inhibition of inflammation; the relieving effect was positively correlated with the dose of CPs. Further investigation showed that CPs first reduce the level of skin oxidation, inhibit the expression of the key transcription factor AP-1 (c-Jun and c-Fos), then activate the TGF-β/Smad signaling pathway to promote collagen synthesis, inhibit the expression of MMP-1/3 to inhibit collagen degradation, and inhibit skin inflammation to alleviate skin aging in mice. Moreover, the skin transcriptome found that lysosomes activated after oral administration of CPs may be an important pathway for CPs in anti-skin aging, and is worthy of further research. These results suggested that CPs might be used as a functional anti-aging nutritional component.

Exogenous Bioactive Peptides Have a Potential Therapeutic Role in Delaying Aging in Rodent Models

In recent years, some exogenous bioactive peptides have been shown to have promising anti-aging effects. These exogenous peptides may have a mechanism similar to endogenous peptides, and some can even regulate the release of endogenous active peptides and play a synergistic role with endogenous active peptides. Most aging studies use rodents that are easy to maintain in the laboratory and have relatively homogenous genotypes. Moreover, many of the anti-aging studies using bioactive peptides in rodent models only focus on the activity of single endogenous or exogenous active peptides, while the regulatory effects of exogenous active peptides on endogenous active peptides remain largely under-investigated. Furthermore, the anti-aging activity studies only focus on the effects of these bioactive peptides in individual organs or systems. However, the pathological changes of one organ can usually lead to multi-organ complications. Some anti-aging bioactive peptides could be used for rescuing the multi-organ damage associated with aging. In this paper, we review recent reports on the anti-aging effects of bioactive peptides in rodents and summarize the mechanism of action for these peptides, as well as discuss the regulation of exogenous active peptides on endogenous active peptides.

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.

Insights into the antibacterial activity of cottonseed protein-derived peptide against Escherichia coli

In the study, antibacterial peptides were separated and identified from cottonseed protein hydrolysates and the interactions between antibacterial peptides and Escherichia coli were further investigated. Firstly, by using a combined strategy of Amberlite CG-50 ion exchange chromatography and reversed-phase high-performance liquid chromatography, three peptides with antibacterial activity were purified and identified, including HHRRFSLY, KFMPT, and RRLFSDY. Interestingly, HHRRFSLY and RRLFSDY exhibited higher inhibition activity with the IC50 value of 0.26 mg mL-1 and 0.58 mg mL-1 (p < 0.05), respectively. Flow cytometry results showed that the incubation of antibacterial peptides with E. coli could cause damage to the integrity of the E. coli cell membrane. Transmission electron microscopy and scanning electron microscopy results revealed the damage caused to the bacterial cell surface and the leakage of cytoplasmic content by the antibacterial peptides. Molecular docking studies indicated that HHRRFSLY, KFMPT, and RRLFSDY have a good binding affinity to the active sites of the surface protein (OmpF) mainly through a hydrogen bond and salt bridge. The results here showed that the antibacterial peptides derived from cottonseed protein could be used as a good choice for functional foods or related drugs, and also shed light on further studies of antibacterial mechanism.

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.

Evaluation and Exploration of Potentially Bioactive Peptides in Casein Hydrolysates against Liver Oxidative Damage in STZ/HFD-Induced Diabetic Rats

Hyperglycemia-induced oxidative stress can cause liver damage in diabetes, and protein hydrolysates with antidiabetic and antioxidant properties are emerging as a potential therapy. In this study, protective effects of casein hydrolysates against live oxidative damage in streptozotocin/high-fat-induced diabetic rats were studied and potentially bioactive peptides were explored by an integrated approach of differential peptide and in silico analysis. Results showed that different casein hydrolysates significantly alleviated liver oxidative damage (p < 0.05) via different mechanisms. Particularly, casein hydrolyzed by a papain-flavourzyme combination (P-FCH) treatment significantly improved liver antioxidant enzyme activities by enhancing nuclear factor erythroid 2-related factor 2 (Nrf2) transcription (p < 0.05). Furthermore, 18 peptides were screened as potential bioactive peptides by analyzing differential peptides among different hydrolysates combined with in silico prediction. Among them, the dipeptide WM might directly inhibit the Kelch-like ECH-associated protein 1 (Keap1)-Nrf2 interaction as potential Nrf2 activators. These results suggested that P-FCH might be an alternative way to treat liver damage in diabetes.

The role of elastin-derived peptides in human physiology and diseases

Once considered as inert, the extracellular matrix recently revealed to be biologically active. Elastin is one of the most important components of the extracellular matrix. Many vital organs including arteries, lungs and skin contain high amounts of elastin to assure their correct function. Physiologically, the organism contains a determined quantity of elastin from the early development which may remain physiologically constant due to its very long half-life and very low turnover. Taking into consideration the continuously ongoing challenges during life, there is a physiological degradation of elastin into elastin-derived peptides which is accentuated in several disease states such as obstructive pulmonary diseases, atherosclerosis and aortic aneurysm. These elastin-derived peptides have been shown to have various biological effects mediated through their interaction with their cognate receptor called elastin receptor complex eliciting several signal transduction pathways. In this review, we will describe the production and the biological effects of elastin-derived peptides in physiology and pathology.

Evaluation of caffeine as inhibitor against collagenase, elastase and tyrosinase using in silico and in vitro approach

Skin ageing results from enhanced activation of intracellular enzymes such as collagenases, elastases and tyrosinase, stimulated by intrinsic ageing and photoageing factors. Recently, caffeine-based cosmetics are introduced that demonstrates to slow down skin photoageing process. However, no attempts have been done so for to understand caffeine functional inhibitory activity against photoageing related enzymes. Hence, this study established the caffeine molecular interaction and inhibition activity profiles against respective enzymes using in silico and in vitro methods, respectively. Results from in silico study indicates that caffeine has comparatively good affinity with collagenase (−4.6 kcal/mol), elastase (−3.36 kcal/mol) and tyrosinase (−2.86 kcal/mol) and formed the stable protein-ligand complex as validated by molecular dynamics simulation (protein-ligand contacts, RMSD, RMSF and secondary structure changes analysis). Moreover, in vitro data showed that caffeine (1000 µg/mL) has statistically significant maximum inhibition activity of 41.86, 36.44 and 13.72% for collagenase, elastase and tyrosinase, respectively.

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.