Recent research progress of biologically active peptides

Novel salty peptides derived from bovine bone: Identification, taste characteristic, and salt-enhancing mechanism

Excessive sodium intake is a major contributor to the incidence of cardiovascular diseases. The objective of this study was to prepare, isolate, and characterize peptides from bovine bone protein and investigate the salty/salt-enhancing mechanism of peptides. 1032 peptides were identified in the enzymatic hydrolysates of bovine bone protein and were further screened by the composition of amino acid residues and molecular docking analysis. 5 peptides were finally selected for solid-phase synthesis, and KER showed a better salty taste by sensory verification. Moreover, the synergistic effect of KER in NaCl and MSG solution could enhance the salty intensity by 65.26 %. The binding of KER to the salty receptor (TMC4) was driven by hydrogen bonding and electrostatic interactions with a binding energy of -88.0734 kcal/mol. This work may provide a new approach to efficiently screen salty peptides from natural food materials, which were expected as a taste enhancer used in salt-reducing foods.

Enhancing storage stability of pea peptides through encapsulation in maltodextrin and gum tragacanth via monitoring scavenge ability to free radicals

Pea peptides can lead to degradation through oxidation, deamidation, hydrolysis, or cyclization during production, processing, and storage, which in turn limit their broader application. To stabilize pea peptides, this study employed spray drying technology to create a pea peptide micro-encapsule using maltodextrin, gum tragacanth, and pea peptides. Four key factors, including polysaccharide ratio, glycopeptide ratio, solid-liquid ratio, and inlet temperature, were optimized to enhance the antioxidant properties of the pea peptide micro-encapsule. The results indicated that the utilization of maltodextrin and gum tragacanth significantly improves the storage stability and antioxidant activity of pea peptides. Moreover, optimal storage stability for pea peptides was achieved with a polysaccharide ratio of 9:1, a glycopeptide ratio of 10:1, a solid-liquid ratio of 4:40, and an inlet temperature of 180 °C. After 60 days of storage, the encapsulated pea peptides maintained 70.22 %, 25.19 %, and 40.32 % for scavenging abilities to hydroxyl radical, superoxide anion, and ABTS radical, respectively. In contrast, the unencapsulated pea peptides showed a decline to 47.02 %, 0 %, and 24.46 % in the same antioxidant activities after storage. These findings underscore the potential of spray drying technology to enhance the functional properties of pea peptides for various applications.

Tissue factor pathway inhibitors disrupt structures of rhabdovirus/ranairidovirus and inhibit viral infection in Chinese perch, Siniperca chuatsi

Viral diseases have caused great economic losses to the aquaculture industry. However, there are currently no specific drugs to treat these diseases. Herein, we utilized Siniperca chuatsi as an experimental model, and successfully extracted two tissue factor pathway inhibitors (TFPIs) that were highly distributed in different tissues. We then designed four novel peptides based on the TFPIs, named TS20, TS25, TS16, and TS30. Among them, TS25 and TS30 showed good biosafety and high antiviral activity. Further studies showed that TS25 and TS30 exerted their antiviral functions by preventing viruses from invading Chinese perch brain (CPB) cells and disrupting Siniperca chuatsi rhabdovirus (SCRV)/Siniperca chuatsi ranairidovirus (SCRIV) viral structures. Additionally, compared with the control group, TS25 and TS30 could significantly reduce the mortality of Siniperca chuatsi, the relative protection rates of TS25 against SCRV and SCRIV were 71.25 % and 53.85 % respectively, and the relative protection rate of TS30 against SCRIV was 69.23 %, indicating that they also had significant antiviral activity in vivo. This study provided an approach for designing peptides with biosafety and antiviral activity based on host proteins, which had potential applications in the prevention and treatment of viral diseases.

An in silico scheme for optimizing the enzymatic acquisition of natural biologically active peptides based on machine learning and virtual digestion

BACKGROUND

As a potential natural active substance, natural biologically active peptides (NBAPs) are recently attracting increasing attention. The traditional proteolysis methods of obtaining effective NBAPs are considerably vexing, especially since multiple proteases can be used, which blocks the exploration of available NBAPs. Although the development of virtual digesting brings some degree of convenience, the activity of the obtained peptides remains unclear, which would still not allow efficient access to the NBAPs. It is necessary to develop an efficient and accurate strategy for acquiring NBAPs.

RESULTS

A new in silico scheme named SSA-LSTM-VD, which combines a sparrow search algorithm-long short-term memory (SSA-LSTM) deep learning and virtually digested, was presented to optimize the proteolysis acquisition of NBAPs. Therein, SSA-LSTM reached the highest Efficiency value reached 98.00 % compared to traditional machine learning algorithms, and basic LSTM algorithm. SSA-LSTM was trained to predict the activity of peptides in the proteins virtually digested results, obtain the percentage of target active peptide, and select the appropriate protease for the actual experiment. As an application, SSA-LSTM was employed to predict the percentage of neuroprotective peptides in the virtual digested result of walnut protein, and trypsin was ultimately found to possess the highest value (85.29 %). The walnut protein was digested by trypsin (WPTrH) and the peptide sequence obtained was analyzed closely matches the theoretical neuroprotective peptide. More importantly, the neuroprotective effects of WPTrH had been demonstrated in nerve damage mouse models.

SIGNIFICANCE

The proposed SSA-LSTM-VD in this paper makes the acquisition of NBAPs efficient and accurate. The approach combines deep learning and virtually digested skillfully. Utilizing the SSA-LSTM-VD based strategy holds promise for discovering and developing peptides with neuroprotective properties or other desired biological activities.

Periplaneta Americana (L.) extract activates the ERK/CREB/BDNF pathway to promote post-stroke neuroregeneration and recovery of neurological functions in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Periplaneta americana (L.) (PA) has been used in traditional Chinese medicine for thousands of years for the effect of invigorating blood circulation and removing blood stasis. Modern pharmacological research shown that PA extract exhibits promising effects in promoting wound healing and regeneration, as well as in brain diseases such as Parkinson's disease (PD). However, whether it is effective for neuroregeneration and neurological function recovery after stroke still unknown.

AIM OF THE STUDY

This study aims to investigate the potential effect of PA extract to promote brain remodeling through the activation of endogenous neurogenesis and angiogenesis, in addition, preliminary exploration of its regulatory mechanism.

METHODS

Firstly, BrdU proliferation assay and immunofluorescence (IF) staining were used to evaluate the effect of PA extract on the neurogenesis and angiogenesis in vitro and in vivo. Subsequently, the effects of PA extract on brain injury in stroke rats were assessed by TTC and HE. While mNSS score, adhesive removal test, rota-rod test, and morris water maze test were used to assess the impact of PA extract on neurological function in post-stroke rats. Finally, the molecular mechanisms of PA extract regulation were explored by RNA-Seq and western blotting.

RESULTS

The number of BrdU+ cells in C17.2 cells, NSCs and BMECs dramatically increased, as well as the expression of astrocyte marker protein GFAP and neuronal marker protein Tuj-1 in C17.2 and NSCs. Moreover, PA extract also increased the number of BrdU+DCX+, BrdU+GFAP+, BrdU+CD31+ cells in the SGZ area of transient middle cerebral artery occlusion model (tMCAO) rats. TTC and HE staining revealed that PA extract significantly reduced the infarction volume and ameliorated the pathological damage. Behavioral tests demonstrated that treatment with PA extract reduced the mNSS score and the time required to remove adhesive tape, while increasing the time spent on the rotarod. Additionally, in the morris water maze test, the frequency of crossing platform and the time spent in the platform quadrant increased. Finally, RNA-Seq and Western blot revealed that PA extract increased the expression of p-ERK, p-CREB and BDNF. Importantly, PA extract mediated proliferation and differentiation of C17.2 and NSCs reversed by the ERK inhibitor SCH772984 and the BDNF inhibitor ANA-12, respectively.

CONCLUSION

Our study demonstrated that PA extract promoted neurogenesis and angiogenesis by activating the CREB/ERK signaling pathway and upregulating BDNF expression, thereby recovering neurological dysfunction in post-stroke.

Characterizations and molecular docking mechanism of the interactions between peptide FDGDF (Phe-Asp-Gly-Asp-Phe) and SOD enzyme

In this study, we investigated the antioxidant properties of dry-cured beef crude peptide (BPH) at different storage periods. The combination characteristics of different concentrations of Phe-Asp-Gly-Asp-Phe (FDGDF) and superoxide dismutase (SOD) at different temperatures were analyzed by ultraviolet-visible spectroscopy, fluorescence spectroscopy, and FT-IR spectroscopy, combined with the detection of a SOD activity detection box. It was found that FDGDF could improve the activity of SOD by changing its secondary structure. Bonds were formed at O32/O40/O52 using quantum chemical simulation calculations, and the Fukui index was higher than that of most atoms, indicating that these atoms were more likely to participate in the reaction. SPR biological force analysis showed that FDGDF and SOD were in a fast binding and dissociation mode. This study revealed the theoretical basis for studying the antioxidant mechanism of dry-cured beef and provided ideas for developing new dry-cured beef products.

Screening and investigation of a short antimicrobial peptide: AVGAV

Bacterial resistance to various drugs is a major problem concerning the field of antibacterial agents. Fortunately, peptides with antibacterial activity can alleviate this problem. In this study, a short peptide (AVGAV) with excellent antibacterial activity was successfully screened from a peptide library by a self-made membrane chromatographic packing. The AVGAV peptide exhibits good biocompatibility and is non-toxic and non-irritating, which ensures that it presents safe antibacterial effects. AVGAV promoted wound healing in a mouse wound bacterial infection model. Most importantly, as a synthetic antimicrobial peptide, AVGAV can alleviate the problem of bacterial resistance, thus improving its application potential. This study provides a solution to the existing and potential problem of bacterial resistance.

Whey Protein Hydrolysate Exerts Anti-Inflammatory Effects to Alleviate Dextran Sodium Sulfate (DSS)-Induced Colitis via Microbiome Restoration

Whey protein hydrolysate (WPH) has been shown to have a variety of bioactivities. This study aimed to investigate the preventive effect of WPH on dextran sodium sulfate (DSS)-induced colitis in C57BL/6J mice. The results indicated that WPH intervention for 37 days was effective in delaying the development of colonic inflammation, and high doses of WPH significantly inhibited weight loss (9.16%, n = 8, p < 0.05), protected the colonic mucosal layer, and significantly reduced the levels of inflammatory factors TNF-α, IL-6, and IL-1β in mice with colitis (n = 8, p < 0.05). In addition, WPH intervention was able to up-regulate the short-chain fatty acids secretion and restore the gut microbiome imbalance in mice with colitis. Notably, high-dose WPH intervention increased the relative abundance of norank_f_Muribaculaceae by 1.52-fold and decreased the relative abundance of Romboutsia and Enterobacter by 3.77-fold and 2.45-fold, respectively, compared with the Model group. WPH intervention protected colitis mice mainly by reversing the microbiome imbalance and regulating the major histocompatibility complex (MHC) class I pathway. This study showed that WPH has anti-inflammatory activity and a promising colitis management future.

Immunotherapy: cancer immunotherapy and its combination with nanomaterials and other therapies

Immunotherapy is a new type of tumor treatment after surgery, radiotherapy and chemotherapy, and can be used to manage and destroy tumor cells through activating or strengthening the immune response. Immunotherapy has the benefits of a low recurrence rate and high specificity compared to traditional treatment methods. Immunotherapy has developed rapidly in recent years and has become a research hotspot. Currently, chimeric antigen receptor T-cell immunotherapy and immune checkpoint inhibitors are the most effective tumor immunotherapies in clinical practice. While tumor immunotherapy brings hope to patients, it also faces some challenges and still requires continuous research and progress. Combination therapy is the future direction of anti-tumor treatment. In this review, the main focus is on an overview of the research progress of immune checkpoint inhibitors, cellular therapies, tumor vaccines, small molecule inhibitors and oncolytic virotherapy in tumor treatment, as well as the combination of immunotherapy with other treatments.

Screening of a short chain antimicrobial peptide-LKLHI and its application in hydrogels for wound healing

Antibacterial peptides have been widely used in the field of antibacterial due to their biocompatibility. In this work, owing to quickly screen out peptides with antibacterial effects, the bacterial membranes of E. coli and S. aureus were extracted and fixed on self-made silica gel microspheres to prepare bacterial membrane chromatography stationary phase. We successfully screened antimicrobial peptides from a peptide library composed of one-bead-one-compound by bacterial membrane chromatography. The antibacterial peptide has an effective defense effect on gram-positive bacteria, gram-negative bacteria, and fungi. In addition, the antibacterial peptide has almost no hemolysis and cytotoxicity and other excellent biocompatibility and has excellent properties such as stability, broad-spectrum antibacterial, and promotion of wound healing，and HA hydrogel carrier loaded with antimicrobial peptides was prepared, which provided the application direction of antimicrobial dressings for antimicrobial peptides. In summary, this method can screen out polypeptides with antibacterial effects, and the screened-out antibacterial peptides are expected to be applied in clinical applications.

Development of KLA-RGD integrated lipopeptide with the effect of penetrating membrane which target the αvβ3 receptor and the application of combined antitumor

Herein, an amphiphilic cationic anticancer lipopeptide P17 with α-helical structure was synthesized based on the integration of KLA and RGD peptide which could bind with the receptor of integrin α_vβ₃. P17 could self assemble into stable spherical aggregates in aqueous solution, and which could encapsulate the anticancer drugs (Such as Dox) to form P17 @ Anticancer drug nanomedicine (P17 @ Dox nanomedicine) which could play the combined therapy of P17 and anticancer drugs (Dox). The encapsulation efficiency of P17 aggregates to Dox was 80.4 ± 3.2 %, and the release behavior of P17 @ Dox nanomedicine in vitro had the characteristics of slow-release and pH responsiveness. The experiments in vitro showed that P17 lipopeptide had low cytotoxicity, high serum stability, low hemolysis and strong penetrating membrane ability. The release of Dox from P17 @ Dox in cells was time-dependment, and the P17 @ Dox nanomedicine had a good anticancer effect. The experiments in vivo showed that P17 and P17 @ Dox nanomedicine both had low hemolysis, and P17 @ Dox nanomedicine could effectively inhibit tumor growth and significantly reduce the toxic and side effects of Dox. Molecular docking experiments showed that P17 could effectively interact with the receptor of integrin α_vβ₃. In conclusion, P17 lipopeptide could be used as an excellent drug carrier and play the combined anticancer effect of P17 and anticancer drugs.

Screening of a short chain antimicrobial peptide-FWKFK and its application in wound healing

As a kind of basic polypeptide with antibacterial properties, antimicrobial peptides play an important role in resisting the invasion of foreign microorganisms. Antimicrobial peptides have a wide range of antimicrobial activities against bacteria, fungi, viruses and other microorganisms. They are active against traditional antibiotic-resistant strains and do not easily cause bacterial resistance. In this study, we synthesized an antibacterial peptide library by a Fmoc solid phase synthesis method, and screened the peptide chain FWKFK by modified cell membrane chromatography. The minimum inhibitory concentration of FWKFK against E. coli and S. aureus was 200 μg mL^-1 and 250 μg mL^-1, respectively, and FWKFK also had inhibitory effects on P. aeruginosa, B. subtilis and S. epidermidis. Its biocompatibility and therapeutic effect on mouse wounds were then tested. The results showed that the survival rate of normal cells after FWKFK treatment was more than 95%, the hemolysis rate of red blood cells was as low as 6%, and it had a significant effect on wound healing in mice.