Structure–Activity Study, Characterization, and Mechanism of Action of an Antimicrobial Peptoid D2 and Its d- and l-Peptide Analogues

Greco, Ines; Hansen, Johannes E.; Jana, Bimal; Molchanova, Natalia; Oddo, Alberto; Thulstrup, Peter W.; Damborg, Peter; Guardabassi, Luca; Pb, Hansen

doi:10.3390/molecules24061121

Cited by 11 publications

(11 citation statements)

References 53 publications

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“…In the present study, we investigated all-d-peptides. Previously, we have shown that D2D is approximately four-fold more active than its l-enantiomer [18]. This is in alignment with several studies which report that the d-enantiomer is more active than the corresponding l-peptide.…”

Section: Alanine Scan Of D2dsupporting

confidence: 91%

“…Previously, we have identified an all-d-peptide, D2D, which shows promising activity against clinical isolates of Methicillin Resistant Staphylococcus pseudintermedius and Pseudomonas aeruginosa. Furthermore, the compound showed moderate toxicity against red blood cells and resistance to proteolytic degradation [18]. D2D consists of 4 cationic residues lys 1 , lys 2 , lys 5 , lys 7 and 4 hydrophobic residues 1-naphthylalanine (1-nal) 3 , phe 4 , 1-nal 6 , norleucine (nle) 8 .…”

Section: Introductionmentioning

confidence: 99%

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Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D

et al. 2019

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The increasing emergence of multi-drug resistant bacteria is a serious threat to public health worldwide. Antimicrobial peptides have attracted attention as potential antibiotics since they are present in all multicellular organisms and act as a first line of defence against invading pathogens. We have previously identified a small all-d antimicrobial octapeptide amide kk(1-nal)fk(1-nal)k(nle)-NH 2 (D2D) with promising antimicrobial activity. In this work, we have performed a structure-activity relationship study of D2D based on 36 analogues aimed at discovering which elements are important for antimicrobial activity and toxicity. These modifications include an alanine scan, probing variation of hydrophobicity at lys 5 and lys 7 , manipulation of amphipathicity, N-and C-termini deletions and lys-arg substitutions. We found that the hydrophobic residues in position 3 (1-nal), 4 (phe), 6 (1-nal) and 8 (nle) are important for antimicrobial activity and to a lesser extent cationic lysine residues in position 1, 2, 5 and 7. Our best analogue 5, showed MICs of 4 µg/mL against A. baumannii, E. coli, P. aeruginosa and S. aureus with a hemolytic activity of 47% against red blood cells. Furthermore, compound 5 kills bacteria in a concentration-dependent manner as shown by time-kill kinetics. Circular dichroism (CD) spectra of D2D and compounds 1-8 showed that they likely fold into α-helical secondary structure. Small angle x-ray scattering (SAXS) experiments showed that a random unstructured polymer-like chains model could explain D2D and compounds 1, 3, 4, 6 and 8. Solution structure of compound 5 can be described with a nanotube structure model, compound 7 can be described with a filament-like structure model, while compound 2 can be described with both models. Lipid interaction probed by small angle X-ray scattering (SAXS) showed that a higher amount of compound 5 (~50-60%) inserts into the bilayer compared to D2D (~30-50%). D2D still remains the lead compound, however compound 5 is an interesting antimicrobial peptide for further investigations due to its nanotube structure and minor improvement to antimicrobial activity compared to D2D.

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Section: Alanine Scan Of D2dsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D

et al. 2019

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“…Including mixed residues in AMPs have previously been shown to prevent the formation of optimised amphiphilic solution structures resulting in lowered biological activities 56 , potentially by altering the peptide membrane localization 57 . The incorporation of D-residues in the structure of AMPs has been related to different mechanisms of action towards bacterial cells 58 and to different affinity towards bacterial peptidoglycan 59 . It is likely that the inclusion of D-residues here limits the interactions between the compounds and targets on or in the erythrocyte membrane.…”

Section: Resultsmentioning

confidence: 99%

Correlation between hemolytic activity, cytotoxicity and systemic in vivo toxicity of synthetic antimicrobial peptides

Greco

Molchanova

Holmedal

et al. 2020

Sci Rep

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288

184

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the use of non-standard toxicity models is a hurdle in the early development of antimicrobial peptides towards clinical applications. Herein we report an extensive in vitro and in vivo toxicity study of a library of 24 peptide-based antimicrobials with narrow spectrum activity towards veterinary pathogens. The haemolytic activity of the compounds was evaluated against four different species and the relative sensitivity against the compounds was highest for canine erythrocytes, intermediate for rat and human cells and lowest for bovine cells. Selected peptides were additionally evaluated against HeLa, HaCaT and HepG2 cells which showed increased stability towards the peptides. Therapeutic indexes of 50-500 suggest significant cellular selectivity in comparison to bacterial cells. Three peptides were administered to rats in intravenous acute dose toxicity studies up to 2-8 × MIC. None of the injected compounds induced any systemic toxic effects in vivo at the concentrations employed illustrating that the correlation between the different assays is not obvious. This work sheds light on the in vitro and in vivo toxicity of this class of promising compounds and provides insights into the relationship between the different toxicity models often employed in different manners to evaluate the toxicity of novel bioactive compounds in general. Antimicrobial peptides (AMPs) have attracted great interest in clinical research over the past three decades as potential therapeutic agents against multidrug resistant bacteria. AMPs are produced by most living organisms and they act as host defense peptides by providing a rapid first line of defense against pathogens 1,2. They come in a variety of sizes and shapes but they are generally cationic and consist of less than 50 amino acids with antimicrobial activities in the low micromolar range 1,3. The discovery that the natural peptides often can be significantly simplified with maintained biological activities makes them plausible candidates for the development of antimicrobials 4-7. Currently, 36 antimicrobial peptides are undergoing preclinical and clinical phase 8 and almost 10,000 papers have been published in 2019 on AMPs. While several natural lipo-and glycopeptides, e.g. colistin and vancomycin, have been approved by the Food and Drug Administration (FDA) as antibiotics, AMPs have yet to make a significant impact on the drug market despite often being heralded as a promising option for the future treatment of drug resistant bacterial and fungal infections 9. AMPs are inherently not metabolically stable and their short half-lives and poor oral bioavailability, combined with potential toxic side effects

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“…In addition to the contextual activity of many AMPs, there are other important concerns such as unclear pharmacokinetic (PK) properties, potential immunogenicity, and host toxicity. Protease digestion can be addressed with l-to-d enantiomerization and the use of unnatural amino acids or peptoids and other types of amino acid mimics [100,[112][113][114][115][116][117]. Importantly, the short sequences of AMPs provide the advantage of conferring poor immunogenicity; however, it is important to rule it out for specific AMPs in clinical development.…”

Section: Contextual Activitymentioning

confidence: 99%

“…Therefore, more transformative structure-function studies are necessary despite bold efforts in clinical development (LL37 for melanoma) [161]. Of note, the use of D-enantiomerization and unnatural amino acids, including peptoids, and cyclization of non-helical AMPs are additional strategies that could be effective in enhancing the pharmacological utility of AMPs [100,[114][115][116]. Both SAAP-148 and ZY4 are based on the modification of a cathelicidin with incorporation of Trp (W) and reduction in the number of amino acid residues to form a more ideal cationic amphipathic structure.…”

Section: Perspectivementioning

confidence: 99%

Engineered Cationic Antimicrobial Peptides (eCAPs) to Combat Multidrug-Resistant Bacteria

et al. 2020

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The increasing rate of antibiotic resistance constitutes a global health crisis. Antimicrobial peptides (AMPs) have the property to selectively kill bacteria regardless of resistance to traditional antibiotics. However, several challenges (e.g., reduced activity in the presence of serum and lack of efficacy in vivo) to clinical development need to be overcome. In the last two decades, we have addressed many of those challenges by engineering cationic AMPs de novo for optimization under test conditions that typically inhibit the activities of natural AMPs, including systemic efficacy. We reviewed some of the most promising data of the last two decades in the context of the advancement of the field of helical AMPs toward clinical development.

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Structure–Activity Study, Characterization, and Mechanism of Action of an Antimicrobial Peptoid D2 and Its d- and l-Peptide Analogues

Cited by 11 publications

References 53 publications

Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D

Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D

Correlation between hemolytic activity, cytotoxicity and systemic in vivo toxicity of synthetic antimicrobial peptides

Engineered Cationic Antimicrobial Peptides (eCAPs) to Combat Multidrug-Resistant Bacteria

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