Antimicrobial peptides (AMPs) are a class of small peptides that widely exist in nature and they are an important part of the innate immune system of different organisms. AMPs have a wide range of inhibitory effects against bacteria, fungi, parasites and viruses. The emergence of antibiotic-resistant microorganisms and the increasing of concerns about the use of antibiotics resulted in the development of AMPs, which have a good application prospect in medicine, food, animal husbandry, agriculture and aquaculture. This review introduces the progress of research on AMPs comprehensively and systematically, including their classification, mechanism of action, design methods, environmental factors affecting their activity, application status, prospects in various fields and problems to be solved. The research progress on antivirus peptides, especially anti-coronavirus (COVID-19) peptides, has been introduced given the COVID-19 pandemic worldwide in 2020.

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Antimicrobial Peptides: Classification, Design, Application and Research Progress in Multiple Fields

phase synthesis was used to produce 5 hybrid peptides containing sequences from the antibacterial peptide, cecropin A, and from the bee venom toxin, melittin. Four of these chimeric peptides showed good antibacterial activity against representative Gram-negative and Gram-positive bacterial species. The best hybrid, cecropin A(l-13)-melittin(l-13) was IOO-fold more active than cecropin A against Staphylococcus uureus. It was also a lo-fold better antimalarial agent than cecropin B or magainin 2. Sheep red cells were lysed by melittin at low concentrations, but not by the hybrid molecules, even at 50 times higher concentrations. Cecropin A; Melittin; (Staphylococcus aureus, Plasmodium falciparium)

and antimalarial properties of peptides that are cecropin-melittin hybrids

Exposure to chromium (Cr) causes a number of respiratory diseases, including lung cancer and pulmonary fibrosis. However, there is currently no safe treatment for Cr-induced lung damage. Here, we used in vivo and in vitro approaches to examine the protective effects of melatonin (MEL) on Cr-induced lung injury and to identify the underlying molecular mechanisms. We found that treatment of rats or a mouse lung epithelial cell MLE-12 with MEL attenuated K2Cr2O7-induced lung injury by reducing the production of oxidative stress and inflammatory mediators and inhibiting cell apoptosis. MEL treatment upregulated the expression of silent information regulator 1 (Sirt1), which deacetylated the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc-1α). In turn, this increased the expression of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and key anti-oxidant target genes. These results suggest that melatonin attenuates chromium-induced lung injury via activating the Sirt1/Pgc-1α/Nrf2 pathway. Dietary MEL supplement may be a potential new strategy for the treatment of Cr poisoning.

Dietary melatonin attenuates chromium-induced lung injury via activating the Sirt1/Pgc-1α/Nrf2 pathway

Design, optimization, and nanotechnology of antimicrobial peptides: From exploration to applications

A composite hydrogel with co-delivery of antimicrobial peptides and platelet-rich plasma to enhance healing of infected wounds in diabetes.

Astragalus polysaccharides attenuated inflammation and balanced the gut microflora in mice challenged with Salmonella typhimurium.

Antibacterial peptides (APMs) are a new type of antibacterial substance. The relationship between their structure and function remains indistinct; in particular, there is a lack of a definitive and fixed template for designing new antimicrobial peptides. Previous studies have shown that porcine Protegrin-1 (PG-1) exhibits considerable antimicrobial activity and cytotoxicity. In this study, to reduce cytotoxicity and increase cell selectivity, we designed histidine-rich peptides based on the sequence template RR(XY)2XDPGX(YX)2RR-NH2, where X represents I, W, V, and F. The results showed that the peptides form more β-hairpin structures in a lipid-rich environment that mimics cell membranes. Among them, the antimicrobial peptide HV2 showed strong antibacterial activity against Gram-negative strains and almost no toxicity to normal cells. The results of our analysis of its antibacterial mechanism showed that peptide HV2 acts on the bacterial cell membrane to increase its permeability, resulting in cell membrane disruption and death. Furthermore, peptide HV2 inhibited bacterial movement in a concentration-dependent manner and had a more robust anti-inflammatory effect by inhibiting the production of TNF-α. In summary, peptide HV2 exhibits high bactericidal activity and cell selectivity, making it a promising candidate for future use as an antibiotic.

https://www.mdpi.com/1422-0067/20/16/3954/pdf

Bioactivity and Bactericidal Mechanism of Histidine-Rich β-Hairpin Peptide Against Gram-Negative Bacteria.

The endotoxin of Gram-negative bacteria threatens the intestinal health of livestock. Ethyl pyruvate (EP) has been shown to regulate intestinal immunity and protect against cell and tissue ...

https://www.tandfonline.com/doi/pdf/10.1080/15384101.2019.1653106

Ethyl pyruvate inhibits LPS induced IPEC-J2 inflammation and apoptosis through p38 and ERK1/2 pathways

Antimicrobial peptides (AMPs) offer great hope and a promising opportunity to overcome the rapid development of drug-resistant pathogenic microbes. However, AMPs often lack the stability required for a successful systemic drug. Hybridizing different AMPs is a simple and effective strategy to obtain novel peptides. N-terminal fragment of cecropin A (CA (1-8)) is often used to hybridize with other AMPs to reduce cytotoxicity. However, hybridizing with CA (1-8) in improving the stability of AMPs is not clear. Therefore, a series of peptides were designed by combining with CA (1-8) and their antibacterial activity and stability in the presence of salts and human serum were evaluated. The resultant α-helical hybrid peptide CA-FO composed of CA (1-8) and the most potent region of Fowlicidin-2 (FO (1-15)) exhibited excellent antibacterial activity (2-8 μM) and cell selectivity toward bacterial over mammalian cells. Moreover, CA-FO still retained vigorous antimicrobial activity in the presence of human serum and salts at physiological concentrations. CA-FO exhibited effective antibacterial activity by increasing membrane permeability and damaging membrane integrity. In conclusion, these results indicated the success of hybridization in designing and optimizing AMPs with improved stability and selectivity and the peptide CA-FO can be further evaluated as peptide-therapy to treat bacterial infections.

Chongpeng Bi

Papers

Astragalus polysaccharides attenuated inflammation and balanced the gut microflora in mice challenged with Salmonella typhimurium.

Bioactivity and Bactericidal Mechanism of Histidine-Rich β-Hairpin Peptide Against Gram-Negative Bacteria.

Ethyl pyruvate inhibits LPS induced IPEC-J2 inflammation and apoptosis through p38 and ERK1/2 pathways

Hybridization with Insect Cecropin A (1-8) Improve the Stability and Selectivity of Naturally Occurring Peptides.