Skin inflammatory signatures, as measured by disordered spatial redness patterns, predict current and future skin ageing attributes.

Facial skin redness can be an indicator of skin inflammation, however the physiological connection between facial redness and inflammatory status, as well as its role in age-related skin changes, remains poorly understood. This study aims to investigate the association between the pattern of facial skin redness and biological inflammatory status, as well as age-related changes occurring in the skin. Four studies were conducted recruiting healthy Northern Asian females. Disordered spatial patterns of facial skin redness signals were assessed using image analysis, i.e., the a* gradient algorithm, which quantifies the disordered shape and pattern of localized redness signals on facial skin. This redness pattern was compared with (1) inflammatory protein markers (IL-1Ra/ IL-1α and IL-8) measured from stripped corneocyte samples, (2) gene expression profiles obtained through transcriptome analysis using skin biopsy samples, and (3) the distribution pattern of blood vessel measured using a photoacoustic microscope. The association between the skin redness pattern and current and future ageing-related skin changes was examined through a longitudinal study tracking the same subjects for 10 years. A significant correlation was observed between the a* gradient and the levels of inflammatory cytokines (IL-1Ra/IL-1α and IL-8). Transcriptome analysis revealed upregulation of genes related to acute inflammation, chronic inflammation, cellular senescence, and angiogenesis in subjects with higher a* gradients. The high a* gradient group exhibited an extension of blood vessel diameter and increased blood vessel density, while the medium a* gradient group only exhibited blood vessel extension. Lastly, the 10-year longitudinal study demonstrated that the a* gradient was associated with current and future skin ageing-related attributes, such as increased skin texture and wrinkle formation. The spatial pattern of localized redness on the skin reflects the biological inflammatory status, and this inflammatory condition helps predict current and future age-related skin changes.

Identification and molecular docking of tyrosinase inhibitory peptides from allophycocyanin in Spirulina platensis.

BACKGROUND: Tyrosinase, a copper-containing metalloenzyme with catalytic activity, is widely found in mammals. It is the key rate-limiting enzyme that catalyzes melanin synthesis. For humans, tyrosinase is beneficial to the darkening of eyes and hair. However, excessive deposition of melanin in the skin can lead to dull skin color and lead to pigmentation. Therefore, many skin-whitening compounds have been developed to decrease tyrosinase activity. This study aimed to identify a new tyrosinase inhibitory peptide through enzymatic hydrolysis, in vitro activity verification, molecular docking, and molecular dynamics (MD) simulation. RESULTS: A tripeptide Asp-Glu-Arg (DER) was identified, with a '-CDOCKER_Energy' value of 121.26 Kcal mol-1 . DER has effective tyrosinase inhibitory activity. Research shows that its half maximal inhibitory concentration value is 1.04 ± 0.01 mmol L-1 . In addition, DER binds to tyrosinase residues His85, His244, His259, and Asn260, which are key residues that drive the interaction between the peptide and tyrosinase. Finally, through MD simulation, the conformational changes and structural stability of the complexes were further explored to verify and supplement the results of molecular docking. CONCLUSION: This experiment shows that DER can effectively inhibit tyrosinase activity. His244, His259, His260, and Asn260 are the critical residues that drive the interaction between the peptide and tyrosinase, and hydrogen bonding is an important force. DER from Spirulina has the potential to develop functional products with tyrosinase inhibition. © 2024 Society of Chemical Industry.

Dissecting the potential mechanism of antihypertensive effects of RVPSL on spontaneously hypertensive rats via widely targeted kidney metabolomics.

BACKGROUND: Our previous study has demonstrated that the egg-white-derived peptide RVPSL can lower blood pressure in spontaneously hypertensive rats (SHRs), but its potential action mechanism remains unclear. In this work, the underlying mechanism of the antihypertensive effects of RVPSL in SHRs was elucidated using the widely targeted kidney metabolomics approach. RESULTS: Ten SHRs were divided into two groups: SHR-Untreated group (0.9% saline) and SHR-RVPSL group (50 mg kg-1 body weight RVPSL) for 4 weeks. After 4 weeks, kidney samples were collected and widely targeted (liquid chromatography-electrospray ionization-tandem mass spectrometry) metabolomics was used to detect metabolites. Fifty-six biomarkers were identified that may be associated with hypertension. Among them, 17 biomarkers were upregulated and 39 biomarkers were downregulated. The results suggested that eight potential biomarkers were identified in kidney samples: O-phospho-l-serine, tyramine, citric acid, 3-hydroxybutyrate, O-acetyl-l-serine, 15-oxo-5Z,8Z,11Z,13E-eicosatetraenoic acid (15-oxoETE), dopaquinone and 3,3',5-triiodo-l-thyronine. These potential biomarkers mainly involved carbon metabolism, thyroid hormone signaling pathway, tyrosine metabolism and arachidonic acid metabolism. CONCLUSION: The study suggested that RVPSL may exert antihypertensive effects through upregulation of O-phospho-l-serine, 3-hydroxybutyrate and 15-oxoETE, and downregulation of tyramine, citric acid, O-acetyl-l-serine, 3,3',5-triiodo-l-thyronine and dopaquinone. The antihypertensive effects of RVPSL may be related to carbon metabolism, thyroid hormone signaling pathway, tyrosine metabolism and arachidonic acid metabolism. RVPSL exhibited a potent antihypertensive effect, and the antihypertensive effects were associated with inhibition of vascular smooth muscle cell proliferation, vascular remodeling, vascular endothelium dysfunction, restoring reactive oxygen species, oxidative stress, inflammation and immune reaction. © 2022 Society of Chemical Industry.

Interaction mechanism of egg derived peptides RVPSL and QIGLF with dipalmitoyl phosphatidylcholine membrane: microcalorimetric and molecular dynamics simulation studies.

BACKGROUND: Egg-derived peptides are becoming increasingly popular due to their biological activity and non-toxic effects. The egg-derived peptides Arg-Val-Pro-Ser-Leu (RVPSL) and Gln-Ile-Gly-Leu-Phe (QIGLF) display strong angiotensin-converting enzyme inhibitory activity and they can be taken up by intestinal epithelial cells. The interaction of the egg-derived peptides RVPSL and QIGLF with the membrane remains unclear. RESULTS: The position and structure of the peptides in the membrane were calculated. The maximum density values of RVPSL and QIGLF were 2.27 and 1.22 nm from the center of the 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) membrane, respectively, indicating that peptides penetrated the membrane-water interface and were embedded in the membrane. The interaction of RVPSL and QIGLF with the DPPC membrane did not affect the average area per lipid or the lipid sequence parameters. The thermodynamic parameters ΔH, ΔG, and ΔS of the interaction between the peptide RVPSL with the DPPC membrane were 17.91 kJ mol-1 , -17.63 kJ mol-1 , 187.5 J mol-1 ·k-1 , respectively. The thermodynamic parameters ΔH, ΔG, and ΔS of the interaction between peptide QIGLF with DPPC membrane were 17.10 kJ mol-1 , -17.12 kJ mol-1 , 114.8 J mol-1 ·k-1 , respectively. CONCLUSION: The results indicated that the binding of peptides RVPSL and QIGLF to DPPC is an endothermic, spontaneous, and entropy-driven reaction. The results of the study are relevant to the problem of the low bioavailability of bioactive peptides (BP). © 2023 Society of Chemical Industry.

A Potential Role of Keratinocyte-Derived Bilirubin in Human Skin Yellowness and Its Amelioration by Sucrose Laurate/Dilaurate.

Sallow and/or dull skin appearance is greatly attributable to the yellow components of skin tone. Bilirubin is a yellow chromophore known to be made in the liver and/or spleen and is transported throughout the body via the blood stream. Recent publications suggest bilirubin may be synthesized in other cells/organs, including the skin. We found human keratinocytes express the transcripts involved in bilirubin biosynthesis. In parallel, we also found human keratinocytes could indeed synthesize bilirubin in monolayer keratinocytes and in a 3D human skin-equivalent model. The synthesized amount was substantial enough to contribute to skin yellowness. In addition, oxidative stress enhanced bilirubin production. Using UnaG, a protein that forms a fluorescent species upon binding to bilirubin, we also visualized the intracellular expression of bilirubin in keratinocytes. Finally, we screened a compound library and discovered that the sucrose laurate/dilaurate (SDL) combination significantly reduced bilirubin levels, as well as bilirubin-mediated yellowness. In conclusion, bilirubin is indeed synthesized in epidermal keratinocytes and can be upregulated by oxidative stress, which could contribute to chronic or transient yellow skin tone appearance. Application of SDL diminishes bilirubin generation and may be a potential solution to mitigate yellowish and/or dull skin appearance.

Xanthine oxidase inhibitory peptides derived from tuna protein: virtual screening, inhibitory activity, and molecular mechanisms.

BACKGROUND: There has been growing interest in the use of xanthine oxidase (XO) as a therapeutic agent to prevent gout and hyperuricemia. In the present study, XO inhibitory peptides were identified from tuna protein by virtual screening, and molecular docking was used to elicit the interaction mechanism between XO and peptides. RESULTS: A novel tetrapeptide, EEAK, exhibited high XO inhibitory activity with an IC50 of 173.00 ± 0.06 µM. Molecular docking analysis revealed that EEAK bound with the pivotal residues of XO's active sites (i.e., Glu802, Arg880, Glu1261) through two conventional hydrogen bond interactions, two attractive charge interactions, and one salt bridge. EEAK could also bind with the residues Phe649, Leu648, Lys771, Ser876, Phe914, and Thr1010 of XO. CONCLUSION: This study suggested that conventional hydrogen bond interactions and electrostatic interactions play an important role in XO inhibition. The novel XO inhibitory peptide EEAK from tuna protein could be used as potential candidate for controlling gout and hyperuricemia. © 2020 Society of Chemical Industry.

Identification of ovalbumin-derived peptides as multi-target inhibitors of AChE, BChE, and BACE1.

BACKGROUND: Alzheimer's disease (AD) is a kind of progressive neurodegenerative disease that affects the elderly. There is no ideal treatment for AD. Thus, the purpose of this study is to identify anti-AD peptides from ovalbumin. RESULTS: The potential tripeptides IEK, LYR, and CIK were selected for molecular docking. The '-CDOCKER_Energy' values of the best docking positions of the tripeptide IEK, LYR, and CIK interacting with acetylcholinesterase (AChE) were 93.8119, 86.9556 and 73.6370 kcal mol-1 , respectively. The '-CDOCKER_Energy' values for interaction with butyrylcholinesterase (BChE) were 96.6386, 80.8392, and 87.4341 kcal mol-1 , respectively. Most importantly, the '-CDOCKER_Energy' values for interaction with ß-site amyloid precursor protein cleavage enzyme1 (BACE1) were 85.5903, 71.3342, and 68.4290 kcal mol-1 , respectively. Overall, in vitro assay results demonstrated that the peptide CIK exhibited impressive inhibitory activities against AChE, BChE, and BACE1, with half maximal inhibitory concentration (IC50 ) values of 6.76, 7.72, and 34.48 µmol L-1 , respectively. In particular, CIK can be joined with some peripheral anion sites (PAS) and catalytic sites on AChE, BChE, and BACE1. CONCLUSION: Tripeptide CIK can effectively inhibit the activities of AChE, BChE, and BACE1. Tripeptide CIK therefore has the potential to treat AD effectively. © 2020 Society of Chemical Industry.

Identification and molecular docking study of novel angiotensin-converting enzyme inhibitory peptides from Salmo salar using in silico methods.

BACKGROUND: In order to circumvent some challenges of the classical approach, the in silico method has been applied to the discovery of angiotensin-converting enzyme (ACE) inhibitory peptides from food proteins. In this study, some convenient and efficient in silico tools were utilized to identify novel ACE inhibitory peptides from Salmo salar. RESULTS: Collagen from Salmo salar was digested in silico into hundreds of peptides. Results revealed that tetrapeptides PGAR and IGPR showed potent ACE inhibitory activity, with IC50 values of 0.598 ± 0.12 and 0.43 ± 0.09 mmol L-1 , respectively. The molecular docking result showed that PGAR and IGPR interact with ACE mostly via hydrogen bonds and attractive charge. Peptide IGPR interacts with Zn+ at the ACE active site, showing high inhibitory activity. CONCLUSION: Interaction with Zn+ in ACE may lead to higher inhibitory activity of peptides, and Pi interactions may promote the effect of peptides on ACE. The in silico method can be an effective method to predict potent ACE inhibitory peptides from food proteins. © 2018 Society of Chemical Industry.

Short- and long-term antihypertensive effect of egg protein-derived peptide QIGLF.

BACKGROUND: The present study aimed to investigate the in vivo antihypertensive effect on spontaneously hypertensive rats (SHRs) induced by egg protein-derived peptide QIGLF, which has been previously characterized in vitro as a potent angiotensin-converting enzyme inhibitor. RESULTS: In vivo antihypertensive effect of QIGLF orally administered was evaluated by the tail-cuff method. The systolic blood pressure and the diastolic blood pressure of rats were measured 0, 5, 10, 15 and 20 h after administration every day. Subsequently, the effect of QIGLF on angiotensin-converting enzyme mRNA expression in the kidney of SHRs was evaluated by a polymerase chain reaction. Systolic blood pressure was found to be reduced markedly in the SHRs after a single oral administration. CONCLUSION: The results show that the effect of QIGLF (50 mg kg-1 body weight) was similar to that of captopril (10 mg kg-1 body weight) with respect to lowering systolic blood pressure in SHRs. Therefore, egg white protein-derived peptide QIGLF may be useful in the prevention or treatment of hypertension. © 2016 Society of Chemical Industry.

[Effect of Clopidogrel on Plasma Protein Binding Rates of Ginsenoside Rg1].

Objective To observe the effect of clopidogrel on plasma protein binding rates of gin- senoside Rg1. Methods Concentrations of ginsenoside Rg1 were measured in fetal bovine serum and phosphate buffered solution (PBS). Samples were randomly divided into ginsenoside Rg1 groups (low: 0.4; middle: 1. 0; high 5. 0 mg/L, respectively) and clopidogrel combined ginsenoside Rg1 groups (low: 0. 4 mg/L +2. 0 mg/L clopidogrel; middle: 1. 0 mg/L +2. 0 mg/L clopidogrel; high: 5. 0 mg/L +2. 0 mg/L clo- pidogrel). The effect of clopidogrel on plasma protein binding rates of ginsenoside Rgl was observed u- sing equilibrium dialysis. Then 3-dimensional structure of bovine serum albumin (BSA) was constructed using homology modeling. On this basis, binding effect of small compounds (ginsenoside Rg1 and clopi- dogrel) and BSA was observed using molecular docking method. Results The serum protein binding rate was 11. 2% ±2. 1% in the low dose ginsenoside Rg1 group, 13. 4% ±2. 2% in the middle dose ginsenoside Rgl group, and 14. 6% ±1. 4% in the high dose ginsenoside Rg1 group, respectively. It was 6. 5% ±2. 3% in the clopidogrel combined low dose ginsenoside Rg1 group, 9. 2% ±1. 5% in the clopi- dogrel combined middle dose ginsenoside Rg1 group, 12.1% ± 1. 7% in the clopidogrel combined high dose ginsenoside Rg1 group, respectively. They were lower in clopidogrel combined ginsenoside Rg1 groups than in ginsenoside Rg1 groups with statistical difference (P <0. 05). Results of molecular doc- king showed that competitive binding effect existed between compounds (ginsenoside Rg1 and clopi- dogrel) and BSA. Conclusion Results of equilibrium dialysis and molecular docking comprehensively in- dicated clopidogrel had effect on plasma protein binding rate of ginsenoside Rg1.

[Study of change in activity of hepatic drug metabolism enzymes in rat model of chronic unpredictable mild stress].

This study aimed to explore the impact of depression caused by chronic unpredictable mild stress (CUMS) on in vivo activity of six kinds of CYP450 isoforms in rats. According to 'Katz' method, the model of CUMS was established. Tolbutamide, chlorzoxazone, theophylline, midazolam, omeprazole and dextromethorphan were chosen as probe substrates of CYP2C6, CYP2E1, CYP1A2, CYP3A2, CYP2D1 and CYP2D2 of rats. Plasma concentration of six kinds of CYP450 in control group and model group were determined by LC-MS/MS and computed pharmacokinetic parameters. Consequently, metabolism of theophylline and chlorzoxazone accelerated significantly (P < 0.01), but tolbutamide, dextromethorphan, omeprazole and midazolam had no significant difference. The present study proved that depression caused by CUMS had strong induction to CYP1A2 and medium induction to CYP2E1.

Application and bioactive properties of proteins and peptides derived from hen eggs: opportunities and challenges.

Several proteins and peptides that are released in vitro and/or in vivo from hen eggs are biologically active and have a variety of functional properties in humans beyond normal nutrition, for which extensive studies have been performed. This review focuses on their biological activities, including antihypertensive, antioxidant, antimicrobial, antiadhesive, immunomodulatory and antithrombotic activities and enhancement of mineral absorption. These proteins and peptides have been shown to regulate the nervous system, cardiovascular system, immune system and gastrointestinal system. The potential application and future directions of research on these bioactive peptides and proteins in the food industry are also addressed.

[Effect of Clopidogrel on Pharmacokinetic of Fufang Danshen Dripping Pill (FDDP)].

OBJECTIVE: To investigate the effect of clopidogrel on the pharmacokinetic of Fufang Danshen Dripping Pill (FDDP); METHODS: 20 SD rats were randomly divided into two group,which were intrinsically administrated FDDP(324 mg/kg) alone and combination of FDDP(324 mg/kg) and clopidogrel(30 mg/kg) respectively for 21 days. The ginsenoside Rg, from FDDP was determined by HPLC and its pharmacokinetic parameter were finally compared. RESULTS: The value of Cmax and AUC0-∞ of ginsenoside Rg, were increased from 1.97 ± 0.44 mg/L and 8.44 ± 2.64 mg/L · h to 2.48 ± 0.63 mg/L and 14.38 ± 5.72 mg/L · h respectively. CONCLUSION: Long term with clopidogrel has effect on the pharmacokinetic character of Rg, from FDDP, this research may provides theoretical support for the FDDP-clopidogrel combination treatment in clinical.

[Synergistic action of Compound Danshen Dripping Pill (CDDP) on Clopidogrel Bisulfate (CPG) counteracting platelet aggregation].

OBJECTIVE: To study the synergistic action of Compound Danshen Dripping Pill (CDDP) on Clopidogrel Bisulfate (CPG) counteracting platelet aggregation. METHODS: 40 Sprague-Dawley (SD) rats were randomized into four groups: normal control group (CMC-Na), CPG alone group (30 mg/kg), CDDP alone group (324 mg/kg), co-administration group (CPG 30 mg/kg and CDDP 324 mg/kg). The rats received gastric infusion of corresponding drugs for 21 continuous days. Blood sample of SD rats were collected by puncture of the abdominal artery for the determination of coagulation parameters such as prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB) concentration and thrombin time (TT) in each group. Another 40 SD rats were used for the observation of inhibitory effect on the thrombosis in arteriovenous shunt. Finally, homology modeling and molecular docking were employed to simulate their interaction between the P2Y purinoceptor 12 (P2Y12) target and bioactive compounds contained in CDDP. RESULTS: The bleeding time of coagulation parameters was prolonged, the thrombosis in arteriovenous shunt was inhibited in the medication group. The above effect was much better in the combination group. The molecular docking showed that bioactive compounds contained in CDDP was able to inhibit target P2Y12. CONCLUSION: CDDP can enhance the effect of CPG on inhibiting platelet aggregation.

Novel Targets and Potential Mechanisms of Mizuhopecten yessoensis-Derived Tripeptide NCW as Antihypertensive Peptides.

SCOPE: Mizuhopecten yessoensis-derived tripeptide Asn-Cys-Trp (NCW) exhibits a potent antihypertensive effect in vivo. However, a lack of knowledge of the antihypertensive mechanism of tripeptide NCW limits its application for functional foods industrialization. The purpose of this study is to elucidate the corresponding targets and mechanisms of tripeptide NCW in hypertension regulation. METHODS AND RESULTS: Administration of tripeptide NCW for 3 weeks, the blood pressure of spontaneously hypertensive rats (SHRs) is significantly decreased. After sacrifice, the serum sample is analyzed using tandem mass tag (TMT)-based liquid chromatography with tandem mass spectrometry to identify differentially expressed proteins. The proteomic analysis indicates that tripeptide NCW administration alters serum protein profiles in SHR rats, significantly upregulating 106 proteins and downregulating 30 proteins. These proteins enhance the glycolysis, glucose, and TCA cycle, improve amino metabolism, trigger the cAMP/PKA, cGMP/PKG, PI3K/AKT, and AMPK signal pathways, and inhibit Ras-regulated JNK activation, TGF-ß/MAPK, and TGF-ß/ RhoA/ROCK pathways. CONCLUSION: Tripeptide NCW supplementation is demonstrated to regulate signal pathways involved in the control of blood pressure and regulate the energy and amino acids metabolic processes in serum, providing important insights into the protective effects of tripeptide NCW on hypertension.

Intestinal absorption of bioactive oligopeptides: paracellular transport and tight junction modulation.

Bioactive oligopeptides have gained increasing attention due to their diverse physiological functions, and these can be transported into the vasculature via transcellular and paracellular pathways. Among these, paracellular transport through the intercellular space is a passive diffusion process without energy consumption. It is currently the most frequently reported absorption route for food-derived bioactive oligopeptides. Previous work has demonstrated that paracellular pathways are mainly controlled by tight junctions, but the mechanism by which they regulate paracellular absorption of bioactive oligopeptides remains unclear. In this review, we summarized the composition of paracellular pathways across the intercellular space and elaborated on the paracellular transport mechanism of bioactive oligopeptides in terms of the interaction between oligopeptides and tight junction proteins, the protein expression level of tight junctions, the signaling pathways regulating intestinal permeability, and the properties of oligopeptides themselves. These findings contribute to a more profound understanding of the paracellular absorption of bioactive oligopeptides.

Identification and Molecular Mechanism of Novel Immunomodulatory Peptides from Gelatin Hydrolysates: Molecular Docking, Dynamic Simulation, and Cell Experiments.

The purpose of this study was to identify donkey-hide gelatin-derived immunomodulatory peptides targeting Toll-like receptor 4-myeloid differentiation 2 (TLR4-MD2) and elucidate their binding modes using physicochemical property prediction, molecular docking, molecular dynamics simulations, and in vitro cell experiments. After hydrolyzing gelatin, 519 peptides were identified by liquid chromatography-tandem mass spectrometry. Peptides VQLSGEEK and GFSGLDGAKG bound to TLR4-MD2 with high binding affinity. In TLR4-MD2, Arg90, Ser118, Phe126, Tyr131, and Arg264 were key residues involved in the binding of these peptides. The RMSD and Rg values demonstrated that VQLSGEEK-TLR4-MD2 and GFSGLDGAKG-TLR4-MD2 complexes had stable and compact conformations. VQLSGEEK and GFSGLDGAKG were found to increase the cell viability and phagocytic activity of RAW264.7 macrophages; significantly promote the production of cytokines TNF-α, IL-1ß, and IL-6 in cells; and inhibit the overproduction of nitric oxide (NO) and cytokines in lipopolysaccharide (LPS)-induced RAW264.7 cells. Our results provided preliminary evidence that VQLSGEEK and GFSGLDGAKG could function as two-way immunomodulatory peptides with immunostimulatory and anti-inflammatory activities.

Underlying antihypertensive mechanism of egg white-derived peptide QIGLF using renal metabolomics analysis.

The kidney is an important target organ in the treatment of hypertension, but the effect of peptide QIGLF with antihypertensive activity on kidneys remains unknown. In the work, we aimed to further understand the hypotensive effects of QIGLF in spontaneously hypertensive rats (SHRs) using widely targeted metabolomics technology to investigate the kidney metabolic profiling variations. After four weeks of oral administration, the results showed different renal metabolomics profiles between QIGLF and model groups. Besides, a total of 10 potential biomarkers were identified, that is, 3-hydroxybutanoate, 20-hydroxyeicosatetraenoic acid, 19(S)-hydroxyeicosatetraenoic acid, 15-oxoETE, L-ornithine, malonate, uridine, uridine 5'-monophosphate, argininosuccinic acid, and N-carbamoyl-L-aspartate. These metabolites might exhibit antihypertensive activity of QIGLF by regulating synthesis and degradation of ketone bodies, arachidonic acid metabolism, pyrimidine metabolism, and arginine biosynthesis. These findings suggest that QIGLF might alleviate hypertension by inhibiting renal inflammation, promoting natriuresis, and regulating renal nitric oxide production.

Identification and molecular mechanism of novel tyrosinase inhibitory peptides from collagen.

This study aimed to identify novel tyrosinase inhibitory peptides from collagen of donkey by combining in silico screening with in vitro activity verification, and to elucidate inhibition mechanism based on molecular docking and molecular dynamics simulation. Three tripeptides, that is, Asp-Gly-Leu (DGL), Gly-Ala-Arg (GAR), and Ser-Asp-Trp (SDW) were identified and exerted potent tyrosinase inhibitory activities, with IC50 values of 0.47 ± 0.01 mM, 1.13 ± 0.04 mM, and 2.08 ± 0.01 mM, respectively. Each of three identified peptides had hydrophobic amino acids and could stably and closely bind with the active pocket of tyrosinase. Hydrogen bonds played the most important roles in impacting the structure stabilities of the peptide-tyrosinase complexes. Moreover, His85, His244, His259, and Asn260 were the key residues to drive the interactions between the peptides and tyrosinase. Overall, collagen-derived peptides DGL, GAR, and SDW from donkey had great potential as tyrosinase inhibitory peptides. PRACTICAL APPLICATION: This study has suggested that three tripeptides DGL, GAR, and SDW derived from collagen of donkey have potent tyrosinase inhibitory activity. These novel collagen-derived peptides had great potential to be applied as tyrosinase inhibitory peptides to prevent and improve hyperpigmentation disorders and other tyrosinase-related problems in the food industry. And this work is expected to provide a theoretical basis for the development of novel, safe, and effective tyrosinase inhibitory peptides.

Interaction mechanism of three egg protein derived ACE inhibitory tri-peptides and DPPC membrane using FS, FTIR, and DSC studies.

Understanding the interaction of food derived angiotensin converting enzyme (ACE) inhibitory peptides and intestinal epithelial cell membrane may help to improve their absorption. This research aimed to study the molecular interaction of ACE inhibitory tri-peptides ADF, FGR, and MIR with DPPC membrane during absorption process. The DPPC liposome was prepared and characterized, then used as a model membrane. The permeability of tri-peptides across the membrane was investigated using Fluorescence spectroscopy. The effect of tri-peptides on the structure and dynamics of DPPC bilayers was determined using Fourier transform infrared spectroscopy. The effect of tri-peptides on the phase transition temperature in the DPPC membrane was also analyzed using Differential scanning calorimetry. The results showed that ACE inhibitory tri-peptides ADF, FGR, and MIR can penetrate into both the membrane-water interface and hydrophobic region of DPPC bilayer, and the tri-peptide FGR have higher permeability across the membrane.