Antibacterial, anti-biofilm, and anti-adhesive activities of melittin, a honeybee venom-derived peptide, against quinolone-resistant uropathogenic Escherichia coli (UPEC)

Animal-derived peptides from Traditional Chinese medicines: medicinal potential, mechanisms, and prospects

ETHNOPHARMACOLOGICAL RELEVANCE

Animal-derived traditional Chinese medicines have a long-standing history in Chinese medicine, which exhibit unique efficacy due to similar structure and function with human tissue. As the major types of constituents that accounted for a relatively high proportion of animal-derived TCMs, peptides with molecular weight between 100 Da and hundreds of thousands of kDa have caught wide attention due to their outstanding bioavailability and excellent specificity.

AIM OF THE STUDY

This review aims to comprehensively delve into the up-to-date research progress in their pharmacology, mechanism, sequence composition, and therapeutic application, laying a solid foundation for future clinical treatment and scientific research.

MATERIALS AND METHODS

Relevant information on the peptides from animal-derived TCMs was collected from scientific literature databases including PubMed, CNKI, literature sources (Ph.D. and M.Sc. dissertations), and Web of Science by using the keywords "Peptides", "Animal", and "TCMs" for gradual screening in the past 30 years.

RESULTS

To date, the peptides from 27 kinds of animal-derived TCMs have been systematically combed. Their pharmacological activity and underlying mechanisms on multiple systems (nervous, circulatory, skeletal, and immune), as well as anti-tumor, antioxidative, and antimicrobial effects, have been sorted out. Besides, the potential safety issues and deficiencies (low bioavailability, imperfect quality management, and toxicity of raw materials) have also been pointed out.

CONCLUSIONS

Comprehensive analysis showed that low development and resource waste accompanied by the inadequate report about the pharmacological activity of most peptides from animal-derived TCMs make it have good research prospects. Although a breakthrough in the field of healthcare products has been made, the development potential for clinical products that bring surprising turnaround will be obtained if the above-mentioned confusions and current needs (improve identification technology and design reasonable dosage forms) are implemented.

Potential Inhibitory Effect of the Peptide Melittin Purified from Apis mellifera Venom on CTX-M-Type Extended-Spectrum β-Lactamases of Escherichia coli

Background. Extended-spectrum β-lactamases (ESBLs) hydrolyze nearly all β-lactam antibiotics, affecting one of the most important groups of antimicrobials used in Gram-negative infections. Among them, CTX-M is the most widespread type of ESBL. This study aimed to evaluate the hydrolytic activity of CTX-M-type ESBLs following exposure to the antimicrobial peptide Melittin. Methods. Melittin was purified from Apis mellifera venom through ultrafiltration and characterized by SDS-PAGE. The minimum inhibitory concentration (MIC) of Melittin against ESBL-producing E. coli was determined by the broth microdilution method. The inhibition of ESBL's hydrolytic activity following exposure to sub-MIC doses of Melittin was quantified using a kinetic assay based on hydrolyzed nitrocefin. Additionally, the effect of Melittin on the expression of the blaCTX-M gene was evaluated via RT-PCR. Results. The peptide fraction of Apitoxin smaller than 10 kDa exhibited a protein band corresponding to Melittin, devoid of higher molecular weight proteins. The MIC of Melittin ranged from 50 to 80 µg/mL. Exposure to Melittin at sub-MIC doses significantly inhibited ESBL hydrolytic activity, reducing it by up to 67%. However, the transcription of the blaCTX-M gene in the presence of Melittin revealed no significant changes. Conclusions. Melittin is able to inhibit ESBL's hydrolytic activity but not blaCTX-M transcription possibly indicating an effect at the translational or post-translational level.

Jelleine, a Family of Peptides Isolated from the Royal Jelly of the Honey Bees (Apis mellifera), as a Promising Prototype for New Medicines: A Narrative Review

The jelleine family is a group of four peptides (jelleines I-IV) originally isolated from the royal jelly of honey bee (Apis mellifera), but later detected in some honey samples. These oligopeptides are composed of 8-9 amino acid residues, positively charged (+2 to +3 at pH 7.2), including 38-50% of hydrophobic residues and a carboxamide C-terminus. Jelleines, generated by processing of the C-terminal region of major royal jelly proteins 1 (MRJP-1), play an important biological role in royal jelly conservation as well as in protecting bee larvae from potential pathogens. Therefore, these molecules present numerous benefits for human health, including therapeutic purposes as shown in preclinical studies. In this review, we aimed to evaluate the biological effects of jelleines in addition to characterising their toxicities and stabilities. Jelleines I-III have promising antimicrobial activity and low toxicity (LD50 > 1000 mg/Kg). However, jelleine-IV has not shown relevant biological potential. Jelleine-I, but not the other analogues, also has antiparasitic, healing, and pro-coagulant activities in addition to indirectly modulating tumor cell growth and controlling the inflammatory process. Although it is sensitive to hydrolysis by proteases, the addition of halogens increases the chemical stability of these molecules. Thus, these results suggest that jelleines, especially jelleine-I, are a potential target for the development of new, effective and safe therapeutic molecules for clinical use.

Synergistic Antibacterial Efficacy of Melittin in Combination with Oxacillin against Methicillin-Resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) often cause infections with high mortality rates. Antimicrobial peptides are a source of molecules for developing antimicrobials; one such peptide is melittin, a fraction from the venom of the Apis mellifera bee. This study aimed to evaluate the antibacterial and antibiofilm activities of melittin and its association with oxacillin (mel+oxa) against MRSA isolates, and to investigate the mechanisms of action of the treatments on MRSA. Minimum inhibitory concentrations (MICs) were determined, and synergistic effects of melittin with oxacillin and cephalothin were assessed. Antibiofilm and cytotoxic activities, as well as their impact on the cell membrane, were evaluated for melittin, oxacillin, and mel+oxa. Proteomics evaluated the effects of the treatments on MRSA. Melittin mean MICs for MRSA was 4.7 μg/mL and 12 μg/mL for oxacillin. Mel+oxa exhibited synergistic effects, reducing biofilm formation, and causing leakage of proteins, nucleic acids, potassium, and phosphate ions, indicating action on cell membrane. Melittin and mel+oxa, at MIC values, did not induce hemolysis and apoptosis in HaCaT cells. The treatments resulted in differential expression of proteins associated with protein synthesis and energy metabolism. Mel+oxa demonstrated antibacterial activity against MRSA, suggesting a potential as a candidate for the development of new antibacterial agents against MRSA.

Therapeutic Prospection of Animal Venoms-Derived Antimicrobial Peptides against Infections by Multidrug-Resistant Acinetobacter baumannii: A Systematic Review of Pre-Clinical Studies

Infections caused by multidrug-resistant Acinetobacter baumannii (MDR-Ab) have become a public health emergency. Due to the small therapeutic arsenal available to treat these infections, health agencies have highlighted the importance of developing new antimicrobials against MDR-Ab. In this context, antimicrobial peptides (AMPs) stand out, and animal venoms are a rich source of these compounds. Here, we aimed to summarize the current knowledge on the use of animal venom-derived AMPs in the treatment of MDR-Ab infections in vivo. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The eight studies included in this review identified the antibacterial activity of eleven different AMPs against MDR-Ab. Most of the studied AMPs originated from arthropod venoms. In addition, all AMPs are positively charged and rich in lysine residues. In vivo assays showed that the use of these compounds reduces MDR-Ab-induced lethality and bacterial load in invasive (bacteremia and pneumonia) and superficial (wounds) infection models. Moreover, animal venom-derived AMPs have pleiotropic effects, such as pro-healing, anti-inflammatory, and antioxidant activities, that help treat infections. Animal venom-derived AMPs are a potential source of prototype molecules for the development of new therapeutic agents against MDR-Ab.