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

Isolation, purification and identification of antibacterial peptides from Jinhua ham broth and molecular simulation analyses of their interaction with bacterial porins

The bioactive peptides in Jinhua ham could be released into the broth during cooking. After comparing peptide antibacterial activity from Jinhua ham broth with varying cooking durations, the cooking-2-h broths were selected for further analysis using cation-exchange and reverse-phase-liquid chromatography. The purified peptide sequences were subsequently synthesized and tested for their antibacterial activity. Four peptides (IKKVVKQASEGP, LGRVPRGKKKL, LKGGKKQLQKL, and MDAIKKKMQMLK) were identified with IC50 values for S. typhimurium and S. aureus below 0.4 mg/mL. Molecular docking and dynamics simulations were employed to investigate the interaction between the four antibacterial peptides and the outer membrane protein F (Omp F) of the Salmonella membrane. All four peptides demonstrated binding energies with Omp F lower than -7 kcal/mol. Stability indicators in molecular dynamics showed minimal fluctuations, further confirming the compactness and stability of the peptide-Omp F complexes. Notably, all four peptides altered the conformation of Omp F, thereby enhancing cell membrane permeability.

Plant-Derived as Alternatives to Animal-Derived Bioactive Peptides: A Review of the Preparation, Bioactivities, Structure-Activity Relationships, and Applications in Chronic Diseases

Background/Objectives: At present, a large number of bioactive peptides have been found from plant sources with potential applications for the prevention of chronic diseases. By promoting plant-derived bioactive peptides (PDBPs), we can reduce dependence on animals, reduce greenhouse gas emissions, and protect the ecological environment. Methods: In this review, we summarize recent advances in sustainably sourced PDBPs in terms of preparation methods, biological activity, structure-activity relationships, and their use in chronic diseases. Results: Firstly, the current preparation methods of PDBPs were summarized, and the advantages and disadvantages of enzymatic method and microbial fermentation method were introduced. Secondly, the biological activities of PDBPs that have been explored are summarized, including antioxidant, antibacterial, anticancer and antihypertensive activities. Finally, based on the biological activity, the structure-activity relationship of PDBPs and its application in chronic diseases were discussed. All these provide the foundation for the development of PDBPs. However, the study of PDBPs still has some limitations. Conclusions: Overall, PDBPs is a good candidate for the prevention and treatment of chronic diseases in humans. This work provides important information for exploring the source of PDBPs, optimizing its biological activity, and accurately designing functional foods or drugs.

Identification and characterization of antibacterial peptides produced by Lactobacillus plantarum 1407

Introduction

Peptides from lactic acid bacteria provide health benefits and can inhibit the growth of pathogenic organisms. The present work aimed to isolate and characterize peptides with antibacterial activity from Lactobacillus plantarum 1407.

Methods

Peptides were isolated and purified from L. plantarum 1407. The effect of various physiological parameters on the antibacterial activity of the isolated peptides was analyzed. The mode of action of the peptides on indicator organisms was observed using transmission microscopy analysis and flow cytometry analysis.

Results

Antibacterial activity and mode of action of peptides isolated from L. plantarum 1407 against gram-positive and gram-negative bacteria have been studied. L. plantarum culture exhibited maximum antibacterial activity at 40 °C, pH 8, and 0.7% salt concentration. The cell-free supernatant (CFS) was concentrated using a 3 kDa ultrafiltration membrane and the peptide fractions (<3 kDa) were further fractionated using Sephadex G-25 gel filtration chromatography. The antibacterial activity of the eluted fractions (F1 to F4) was evaluated using flow cytometry and transmission electron microscopy. F3 fraction exhibited increased antibacterial activity than F1, F2, and F4 fractions against the indicator organisms. Cell membrane damage and leakage of cytoplasmic content of the bacterial cells treated with the antibacterial F3 fraction peptides were observed.

Conclusion

The active peptides from L. plantarum 1407 can be potentially used for the treatment of bacterial infections.

Structural Analysis and Antimicrobial Mechanism of a Protein GBSPI-A from Ginkgo Biloba Seed

Ginkgo biloba seed has antimicrobial activity. In this study, ginkgo biloba seed protein was prepared, identified, and named GBSPI-A, finding its construction was similar to 11-S globulin. Then, the influence of GBSPI-A on the cell membrane and physiological metabolism of K. pneumoniae and S. aureus were investigated. The results showed that GBSPI-A (20 mg/mL) destroyed the cell membrane, causing leakage of intracellular material and inhibited bacterial growth with an inhibition rate of approximately 80%. In addition, the GBSPI-A (10 mg/mL) caused the decreasing activity of ATPase and respiratory rate, and the respiratory depression rate was 7.24%. Furthermore, the decreasing ATP synthesis and intracellular β-galactosidase activity led to an insufficient supply of physiological metabolic energy. Therefore, the results showed that GBSPI-A could be used as a natural bacteriostatic agent to replace related drugs and also provide a new insight into the application of GBSPI-A in food safety.

Identification of Bcl2 as a Stably Expressed qPCR Reference Gene for Human Colon Cancer Cells Treated with Cottonseed-Derived Gossypol and Bioactive Extracts and Bacteria-Derived Lipopolysaccharides

Cottonseed contains many bioactive molecules including plant polyphenols. Cottonseed value might be increased by providing high-value bioactive polyphenols for improving nutrition and health. However, there was a lack of molecular evidence for cottonseed bioactivity in mammalian cells. One widely used method for evaluating the bioactivity of natural products is quantitative real-time-PCR (qPCR). The selection of stably expressed internal reference genes is a crucial task of qPCR assay for data analysis. The rationale for reference gene selection is that a lower standard deviation of the cycle of threshold (Cq) among the treatments indicates a more stable expression of the gene. The objective of this study was to select reference genes in human colon cancer cells (COLO 205) treated with cottonseed-derived gossypol and bioactive extracts along with bacterial endotoxin lipopolysaccharides (LPS). SYBR Green qPCR was used to analyze the mRNA levels of a wide range of biomarkers involved in glucose transport, lipid biosynthesis, inflammatory response, and cancer development. qPCR data (10,560 Cq values) were generated from 55 genes analyzed from 64 treatments with triplicate per treatment for each gene. The data showed that B-cell lymphoma 2 (Bcl2) mRNA was the most stable among the 55 mRNAs analyzed in the human colon cancer cells. Glyceraldehyde 3 phosphate dehydrogenase (Gapdh) and ribosome protein L32 (Rpl32) mRNAs were not good qPCR references for the colon cancer cells. These observations were consistent regardless of the treatment comparison between gossypol and LPS, glanded and glandless seed extracts, seed coat and kernel extracts, or treatment for 8 and 24 h. These results suggest that Bcl2 is a preferable reference gene for qPCR assays in human colon cancer cells treated with cottonseed-derived gossypol and bioactive extracts as well as LPS. The extensive qPCR results firmly support the conclusion that the Bcl2 gene is stably expressed at the mRNA level in the human colon cancer cells regardless of the treatment, suggesting that Bcl2 gene expression is not regulated at the mRNA level but at the post-transcriptional level. These results should facilitate studies designated to evaluate bioactivity on gene expression regulation by cottonseed molecules and other natural and synthetic molecules for nutrition and health uses.

Resveratrol Triggered the Quick Self-Assembly of Gallic Acid into Therapeutic Hydrogels for Healing of Bacterially Infected Wounds

Programing self-assembly of naturally bioactive molecules has been a wide topic of great significance for biomedical uses. Despite the fact that plant-derived polyphenols with catechol or pyrogallol moieties have been widely studied to construct nanocomplexes or nanocoatings via self-polymerization, there is no report on the self-assembly of these polyphenols into therapeutic hydrogels for potential applications. Here, we reported that adding a very small amount of resveratrol (Res) into the gallic acid (GA) aqueous solution could trigger the quick self-assembly of GA to form a fibrous hydrogel within 5 min through hydrogen bonds and π-π interactions. The length of GA/Res (GR) fibrils in gels varied from 100 to 1000 microns, with a diameter of around 1 μm. Notably, these GR hydrogels showed excellent colloid stability, providing better slow release and outstanding biocompatibility. Also, in vivo experiments indicated the hydrogels had high antibacterial effects and excellent wound healing capabilities in a total skin defect model via regulating the expression of inflammatory factors (IL-6, IL-1β, and TNF-α) due to the release of therapeutic agents (GA and Res) into the matrix. Overall, our results provide a new strategy to accelerate self-assembly of GA by adding Res to form hydrogels, which is further proved as a promising therapeutic carrier for wound healing.