Activity of MSI-78, h-Lf1-11 and cecropin B antimicrobial peptides alone and in combination with voriconazole and amphotericin B against clinical isolates of Fusarium solani

Various Biomimetics, Including Peptides as Antifungals

Biomimetics, which are similar to natural compounds that play an important role in the metabolism, manifestation of functional activity and reproduction of various fungi, have a pronounced attraction in the current search for new effective antifungals. Actual trends in the development of this area of research indicate that unnatural amino acids can be used as such biomimetics, including those containing halogen atoms; compounds similar to nitrogenous bases embedded in the nucleic acids synthesized by fungi; peptides imitating fungal analogs; molecules similar to natural substrates of numerous fungal enzymes and quorum-sensing signaling molecules of fungi and yeast, etc. Most parts of this review are devoted to the analysis of semi-synthetic and synthetic antifungal peptides and their targets of action. This review is aimed at combining and systematizing the current scientific information accumulating in this area of research, developing various antifungals with an assessment of the effectiveness of the created biomimetics and the possibility of combining them with other antimicrobial substances to reduce cell resistance and improve antifungal effects.

Antimicrobial Peptide Synergies for Fighting Infectious Diseases

Antimicrobial peptides (AMPs) are essential elements of thehost defense system. Characterized by heterogenous structures and broad-spectrumaction, they are promising candidates for combating multidrug resistance. Thecombined use of AMPs with other antimicrobial agents provides a new arsenal ofdrugs with synergistic action, thereby overcoming the drawback of monotherapiesduring infections. AMPs kill microbes via pore formation, thus inhibitingintracellular functions. This mechanism of action by AMPs is an advantage overantibiotics as it hinders the development of drug resistance. The synergisticeffect of AMPs will allow the repurposing of conventional antimicrobials andenhance their clinical outcomes, reduce toxicity, and, most significantly,prevent the development of resistance. In this review, various synergies ofAMPs with antimicrobials and miscellaneous agents are discussed. The effect ofstructural diversity and chemical modification on AMP properties is firstaddressed and then different combinations that can lead to synergistic action,whether this combination is between AMPs and antimicrobials, or AMPs andmiscellaneous compounds, are attended. This review can serve as guidance whenredesigning and repurposing the use of AMPs in combination with other antimicrobialagents for enhanced clinical outcomes.

Antibacterial and Anti-Inflammatory Properties of Peptide KN-17

Peri-implantitis, an infectious disease originating from dental biofilm that forms around dental implants, which causes the loss of both osseointegration and bone tissue. KN-17, a truncated cecropin B peptide, demonstrated efficacy against certain bacterial strains associated with peri-implantitis. This study aimed to assess the antibacterial and anti-inflammatory properties and mechanisms of KN-17. The effects of KN-17 on oral pathogenic bacteria were assessed by measuring its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Moreover, the cytotoxicity and anti-inflammatory effects of KN-17 were evaluated. KN-17 inhibited the growth of Streptococcus gordonii and Fusobacterium nucleatum during in vitro biofilm formation and possessed low toxicity to hBMSCs cells. KN-17 also caused RAW264.7 macrophages to transform from M1 to M2 by downregulating pro-inflammatory and upregulating anti-inflammatory factors. It inhibited the NF-κB signaling pathway by reducing IκBα and P65 protein phosphorylation while promoting IκBα degradation and nuclear P65 translocation. KN-17 might be an efficacious prophylaxis against peri-implant inflammation.

Screening of Rhamnus Purpurea (Edgew.) Leaves for Antimicrobial, Antioxidant, and Cytotoxic Potential

Exploring new antimicrobial and cytotoxic drugs has been one of the most active areas of research. Rhamnus purpurea (Edgew.) buckthorn (Rhamnaceae) is a wild shrub traditionally used in Pakistan for the treatment of various ailments including cancer and infectious diseases. The aim of this study is to find novel antimicrobial and cytotoxic agents of plant origin. The crude methanol extract and full range of fractions of R. purpurea leaves were screened for the said activities using in vitro antimicrobial, antioxidant, and cytotoxic models following standard protocols. The antimicrobial activity was evaluated using the agar well diffusion method, while the antioxidant activity was assessed with 1,1-diphenyl-2-picryl hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The cytotoxic effect was investigated against the human cancer cell lines i.e. Caco-2 (gut), A549 (lung), HepG2 (liver), and MDA-MB-231 (breast) by MTS assay. In addition, toxicity studies were conducted on renal and alveolar primary epithelial cells (HRPTEpiC and HPAEpiC, respectively). Phytochemical investigation showed the presence of secondary metabolites such as alkaloids, saponins, tannins, glycosides, phenols, carbohydrates, proteins, and flavonoids. The n-hexane and chloroform fractions showed significant activity against Staphylococcus aureus (MIC 0.60 and 0.68 mg/mL, respectively), Salmonella typhi (MIC 0.48 and 0.45 mg/mL, respectively), and Bacillus subtilis (MIC 0.54 and 0.76 mg/mL, respectively). Among fungal strains, crude methanol and chloroform fractions exhibited significant activity against Fusarium solani (MIC 0.53 and 0.44 mg/mL, respectively) and Aspergillus niger (MIC 0.47 and 0.42 mg/mL, respectively). The crude methanol, n-hexane and chloroform fractions revealed the highest antioxidant activity at 1000 μg/mL, compared to that of ascorbic acid. The n-hexane fraction showed a significant cytotoxic effect against Caco-2, A549, and HepG2 cell lines with IC50 values of 5.65 ± 0.88, 5.50 ± 0.90, and 4.95 ± 1.0 μg/mL, respectively. Similarly, the chloroform fraction depicted significant activity against Caco-2, A549, and HepG2 cell lines with IC50 values of 4.55 ± 1.25, 4.65 ± 1.55, and 2.85 ± 0.98 μg/mL, respectively. The crude methanol extract and almost all fractions exhibited the highest selectivity index (>2.0) for Caco-2, A549, and HepG2 cancer cell lines, providing safety data for this study. The results showed that R. purpurea leaves have excellent antimicrobial, antioxidant, and cytotoxic potential and warrant further studies to search for novel compounds for the said activities.

Anti-Pythium insidiosum activity of MSI-78, LL-37, and magainin-2 antimicrobial peptides

We investigated the anti-Pythium insidiosum activity of the antimicrobial peptides (AMPs) MSI-78, LL-37, and magainin-2. To detect the minimum inhibitory concentration (MIC), fourteen clinical strains were incubated with the AMPs following the CLSI M38-A2 protocol. All three AMPs showed antimicrobial activity with an MIC range of 20-80 mg/L against all strains. We concluded that the evaluated AMPs have great potential as anti-Pythium insidiosum agents, and their activity deserves to be more explored in further research. Antimicrobial peptides were tested against Pythium insidiosum, a microorganism that causes a difficult-to-treat disease in animals and humans. These peptides have been shown to be able to kill P. insidiosum and may be candidates for use in the treatment of this infection.