Change search
Refine search result
1 - 35 of 35
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abdillahi, Suado M.
    et al.
    Lund Univ, Div Infect Med, Dept Clin Sci, Tornavagen 10, S-22184 Lund, Sweden.
    Maass, Tobias
    Univ Cologne, Fac Med, Ctr Biochem, Ctr Mol Med Cologne, D-50931 Cologne, Germany.
    Kasetty, Gopinath
    Lund Univ, Div Resp Med & Allergol, Dept Clin Sci, S-22184 Lund, Sweden.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Baumgarten, Maria
    Lund Univ, Div Infect Med, Dept Clin Sci, Tornavagen 10, S-22184 Lund, Sweden.
    Tati, Ramesh
    Lund Univ, Div Infect Med, Dept Clin Sci, Tornavagen 10, S-22184 Lund, Sweden.
    Nordin, Sara L.
    Lund Univ, Div Infect Med, Dept Clin Sci, Tornavagen 10, S-22184 Lund, Sweden.
    Walse, Björn
    Sarom Biostruct AB, S-22363 Lund, Sweden.
    Wagener, Raimund
    Univ Cologne, Fac Med, Ctr Biochem, Ctr Mol Med Cologne, D-50931 Cologne, Germany.
    Schmidtchen, Artur
    Lund Univ, Div Dermatol & Venereol, Dept Clin Sci, S-22184 Lund, Sweden;Univ Copenhagen, Bispebjerg Hosp, Dept Biomed Sci, Copenhagen Wound Healing Ctr, DK-2400 Copenhagen, Denmark.
    Mörgelin, Matthias
    Lund Univ, Div Infect Med, Dept Clin Sci, Tornavagen 10, S-22184 Lund, Sweden;Colzyx AB, S-22381 Lund, Sweden.
    Collagen VI Contains Multiple Host Defense Peptides with Potent In Vivo Activity2018In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 201, no 3, p. 1007-1020Article in journal (Refereed)
    Abstract [en]

    Collagen VI is a ubiquitous extracellular matrix component that forms extensive microfibrillar networks in most connective tissues. In this study, we describe for the first time, to our knowledge, that the collagen VI von Willebrand factor type A like domains exhibit a broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria in human skin infections in vivo. In silico sequence and structural analysis of VWA domains revealed that they contain cationic and amphipathic peptide sequence motifs, which might explain the antimicrobial nature of collagen VI. In vitro and in vivo studies show that these peptides exhibited significant antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa through membrane disruption. Our findings shed new light on the role of collagen VI derived peptides in innate host defense and provide templates for development of peptide-based antibacterial therapies.

  • 2.
    Aboye, Teshome L.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bruhn, Jan G.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    El-Seedi, Hesham
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Rosengren, K. Johan
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    A Cactus-Derived Toxin-Like Cystine Knot Peptide with Selective Antimicrobial Activity2015In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 16, no 7, p. 1068-1077Article in journal (Refereed)
    Abstract [en]

    Naturally occurring cystine knot peptides show a wide range of biological activity, and as they have inherent stability they represent potential scaffolds for peptide-based drug design and biomolecular engineering. Here we report the discovery, sequencing, chemical synthesis, three-dimensional solution structure determination and bioactivity of the first cystine knot peptide from Cactaceae (cactus) family: Ep-AMP1 from Echinopsis pachanoi. The structure of Ep-AMP1 (35 amino acids) conforms to that of the inhibitor cystine knot (or knottin) family but represents a novel diverse sequence; its activity was more than 500 times higher against bacterial than against eukaryotic cells. Rapid bactericidal action and liposome leakage implicate membrane permeabilisation as the mechanism of action. Sequence homology places Ec-AMP1 in the plant C6-type of antimicrobial peptides, but the three dimensional structure is highly similar to that of a spider neurotoxin.

  • 3.
    Bohlin, Lars
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Felth, Jenny
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bioassays in natural product research - Strategies and methods in the search for bioactive natural products2014In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 80, no 10, p. 753-753Article in journal (Other academic)
  • 4.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Chemistry and Biology of Cyclotides: Circular Plant Peptides Outside the Box2014In: Journal of natural products (Print), ISSN 0163-3864, E-ISSN 1520-6025, Vol. 77, no 3, p. 724-736Article, review/survey (Refereed)
    Abstract [en]

    Cyclotides stand out as the largest family of circular proteins of plant origin hitherto known, with more than 280 sequences isolated at peptide level and many more predicted from gene sequences. Their unusual stability resulting from the signature cyclic cystine knot (CCK) motif has triggered a broad interest in these molecules for potential therapeutic and agricultural applications. Since the time of the first cyclotide discovery, our laboratory in Uppsala has been engaged in cyclotide discovery as well as the development of protocols to isolate and characterize these seamless peptides. We have also developed methods to chemically synthesize cyclotides by Fmoc-SPPS, which are useful in protein grafting applications. In this review, experience in cyclotide research over two decades and the recent literature related to their structures, synthesis, and folding as well the recent proof-of-concept findings on their use as "epitope" stabilizing scaffolds are summarized.

  • 5.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Cyclotide-membrane interactions: defining factors of membrane binding, depletion and disruption2011In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1808, no 11, p. 2665-2673Article in journal (Refereed)
    Abstract [en]

    The cyclotide family of plant-derived peptides is defined by a cyclic backbone and three disulfide bonds locked into a cyclic cystine knot. They display a diverse range of biological activities, many of which have been linked to an ability to target biological membranes. In the current work, we show that membrane binding and disrupting properties of prototypic cyclotides are dependent on lipid composition, using neutral (zwitterionic) membranes with or without cholesterol and/or anionic lipids. Cycloviolacin O2 (cyO2) caused potent membrane disruption, and showed selectivity towards anionic membranes, whereas kalata B1 and kalata B2 cyclotides were significantly less lytic towards all tested model membranes. To investigate the role of the charged amino acids of cyO2 in the membrane selectivity, these were neutralized using chemical modifications. In contrast to previous studies on the cytotoxic and antimicrobial effects of these derivatives, the Glu6 methyl ester of cyO2 was more potent than the native peptide. However, using membranes of Escherichia coil lipids gave the opposite result: the activity of the native peptide increased 50-fold. By using a combination of ellipsometry and LC-MS, we demonstrated that this unusual membrane specificity is due to native cyO2 extracting preferentially phosphatidylethanolamine-lipids from the membrane, i.e., PE-C16:0/cyC17:0 and PE-C16:0/C18:1.

  • 6.
    Forde, Eanna
    et al.
    Royal Coll Surgeons Ireland, Dept Chem, 123 St Stephens Green, Dublin 2, Ireland;Royal Coll Surgeons Ireland, Dept Clin Microbiol, Dublin 9, Ireland.
    Shafiy, Ghady
    Royal Coll Surgeons Ireland, Dept Chem, 123 St Stephens Green, Dublin 2, Ireland;Royal Coll Surgeons Ireland, Dept Clin Microbiol, Dublin 9, Ireland.
    Fitzgerald-Hughes, Deirdre
    Royal Coll Surgeons Ireland, Dept Clin Microbiol, Dublin 9, Ireland.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Devocelle, Marc
    Royal Coll Surgeons Ireland, Dept Chem, 123 St Stephens Green, Dublin 2, Ireland.
    Action of antimicrobial peptides and their prodrugs on model and biological membranes2018In: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 24, no 7, article id e3086Article in journal (Refereed)
    Abstract [en]

    Antimicrobial peptides (AMPs) are promising broad-spectrum antibiotic candidates in the wake of multi-drug resistant pathogens. Their clinical use still requires a solution based on lead optimisation and/ or formulation to overcome certain limitations, such as unwanted cytotoxicity. A prodrug approach could overcome this safety barrier and can be achieved through reversible reduction or neutralisation of the AMPs' net cationic charge. By prodrug activation through pathogen associated enzymes, this approach could increase the therapeutic index of membrane active peptides. P18, a cecropin/ magainin hybrid, and WMR, a myxinidin analogue from hagfish, were used as templates for the design strategy. The membrane permeabilizing activities of these AMPs and their prodrugs are reported here for liposomes of either Escherichia coli polar lipid extract or a human model lipid system of phosphatidylcholine and cholesterol. These results are compared with their antibacterial and haemolytic activities. Overall, correlation between liposome permeabilization and the corresponding bioactivity is observed and indicate that the broad-spectrum antibacterial effect exerted by these peptides is associated with membrane disruption. Furthermore, the prodrug modification had a general negative influence on membrane disruption and bioactivity, notably as much on bacterial as on human membranes. This prodrug strategy is particularly successful when complete neutralisation of the AMP's net charge occurs. Thus, on-target selectivity between bacterial and human membranes can be improved, which may be used to prevent the unnecessary exposure of host cells and commensal bacteria to active AMPs.

  • 7.
    Gunasekera, Sunithi
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Muhammad, Taj
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Backbone-Cyclized Peptide Dimers Derived from Human Cathelicidin Peptide LL-37 Mediate Potent Antimicrobial Activity2014In: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 20, p. S270-S271Article in journal (Other academic)
  • 8.
    Gunasekera, Sunithi
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Muhammad, Taj
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Rosengren, K. Johan
    Univ Queensland, Sch Biomed Sci, Brisbane, Qld 4072, Australia.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Alanine and Lysine Scans of the LL-37-Derived Peptide Fragment KR-12 Reveal Key Residues for Antimicrobial Activity2018In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 19, no 9, p. 931-939Article in journal (Refereed)
    Abstract [en]

    The human host defence peptide LL-37 is a broad-spectrum antibiotic with immunomodulatory functions. Residues 18-29 in LL-37 have previously been identified as a minimal peptide (KR-12) that retains antibacterial activity with decreased cytotoxicity. In this study, analogues of KR-12 were generated by Ala and Lys scans to identify key elements for activity. These were tested against a panel of human pathogens and for membrane permeabilisation on liposomes. Replacements of hydrophobic and cationic residues with Ala were detrimental for antibiotic potency. Substitutions by Lys increased activity, as long as the increase in cationic density did not disrupt the amphiphilic disposition of the helical structure. Importantly, substitutions showed differential effects against different organisms. Replacement of Gln5 with Lys and Asp9 with Ala or Lys improved the broad-spectrum activity most, each resulting in up to an eightfold increase in potency against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The improved analogues displayed no significant toxicity against human cells, and thus, KR-12 is a tuneable template for antibiotic development.

  • 9.
    Göransson, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Burman, Robert
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Rosengren, K. Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Circular Proteins from Plants and Fungi2012In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, no 32, p. 27001-27006Article, review/survey (Refereed)
    Abstract [en]

    Circular proteins, defined as head-to-tail cyclized polypeptides originating from ribosomal synthesis, represent a novel class of natural products attracting increasing interest. From a scientific point of view, these compounds raise questions of where and why they occur in nature and how they are formed. From a rational point of view, these proteins and their structural concept may be exploited for crop protection and novel pharmaceuticals. Here, we review the current knowledge of three protein families: cyclotides and circular sunflower trypsin inhibitors from the kingdom of plants and the Amanita toxins from fungi. A particular emphasis is placed on their biological origin, structure, and activity. In addition, the opportunity for discovery of novel circular proteins and recent insights into their mechanism of action are discussed.

  • 10.
    Göransson, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Malik, S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Park, S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Slazak, Blazej
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Jacobsson, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Eriksson, Camilla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Andersson, H.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Peptide biodiscovery from plants and animals: structure to function2016In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 82Article in journal (Other academic)
  • 11.
    Häffner, Sara Malekkhaiat
    et al.
    Univ Copenhagen, Dept Pharm, Wound Healing Ctr, Bispebjerg Hosp, DK-2100 Copenhagen, Denmark.
    Nyström, Lina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Browning, Kathryn L.
    Univ Copenhagen, Dept Pharm, Wound Healing Ctr, Bispebjerg Hosp, DK-2100 Copenhagen, Denmark.
    Nielsen, Hanne Mörck
    Univ Copenhagen, Dept Pharm, Wound Healing Ctr, Bispebjerg Hosp, DK-2100 Copenhagen, Denmark.
    Strömstedt, Adam A.
    Univ Copenhagen, Dept Med Chem, Wound Healing Ctr, Bispebjerg Hosp,Pharmacognosy, DK-2100 Copenhagen, Denmark.
    van der Plas, Mariena J. A.
    Univ Copenhagen, Dept Pharm, Wound Healing Ctr, Bispebjerg Hosp, DK-2100 Copenhagen, Denmark;Lund Univ, Dept Clin Sci, Div Dermatol & Venereol, SE-22184 Lund, Sweden.
    Schmidtchen, Artur
    Univ Copenhagen, Dept Biomed Sci, Wound Healing Ctr, Bispebjerg Hosp, DK-2100 Copenhagen, Denmark;Lund Univ, Dept Clin Sci, Div Dermatol & Venereol, SE-22184 Lund, Sweden.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Univ Copenhagen, Dept Pharm, Wound Healing Ctr, Bispebjerg Hosp, DK-2100 Copenhagen, Denmark.
    Interaction of Laponite with Membrane Components - Consequences for Bacterial Aggregation and Infection Confinement2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 17, p. 15389-15400Article in journal (Refereed)
    Abstract [en]

    The antimicrobial effects of Laponite nano particles with or without loading of the antimicrobial peptide LL-37 was investigated along with their membrane interactions. The study combines data from ellipsometry, circular dichroism, fluorescence spectroscopy, particle size/zeta potential measurements, and confocal microscopy. As a result of the net negative charge of Laponite, loading of net positively charged LL-37 increases with increasing pH. The peptide was found to bind primarily to the outer surface of the Laponite nanoparticles in a predominantly helical conformation, leading to charge reversal. Despite their net positive charge, peptide-loaded Laponite nanoparticles did not kill Gram-negative Escherichia coli bacteria or disrupt anionic model liposomes. They did however cause bacteria flocculation, originating from the interaction of Laponite and bacterial lipopolysaccharide (LPS). Free LL-37, in contrast, is potently antimicrobial through membrane disruption but does not induce bacterial aggregation in the concentration range investigated. Through LL-37 loading of Laponite nanoparticles, the combined effects of bacterial flocculation and membrane lysis are observed. However, bacteria aggregation seems to be limited to Gram-negative bacteria as Laponite did not cause flocculation of Gram-positive Bacillus subtilis bacteria nor did it bind to lipoteichoic acid from bacterial envelopes. Taken together, the present investigation reports several novel phenomena by demonstrating that nanoparticle charge does not invariably control membrane destabilization and by identifying the ability of anionic Laponite nanoparticles to effectively flocculate Gram-negative bacteria through LPS binding. As demonstrated in cell experiments, such aggregation results in diminished LPS-induced cell activation, thus outlining a promising approach for confinement of infection and inflammation caused by such pathogens.

  • 12.
    Jacobsson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Andersson, Håkan S.
    Karolinska Institutet, Department of Medical Biochemistry and Biophysics, 2Division of Molecular Structural Biology.
    Avila, Conxita
    University of Barcelona, Faculty of Biology, Department of Evolutionary Biology, Ecology, and Environmental Sciences, and Biodiversity Research Institute (IrBIO).
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Peptide toxins from the Antarctica: the nemertean predator and scavenger Parborlasia corrugatusManuscript (preprint) (Other academic)
  • 13.
    Khan, T. M.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Roy, D.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Structure and Activity Relationship of the Echinochloa Crus-Galli Antimicrobial Peptide 12014In: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 20, p. S278-S279Article in journal (Other academic)
  • 14.
    Kirkpatrick, Christine L.
    et al.
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    Broberg, Christopher A.
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    McCool, Elijah N.
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    Lee, Woo Jean
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    Chao, Alex
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    McConnell, Evan W.
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    Pritchard, David A.
    Univ North Carolina Chapel Hill, Dept Biostat, Chapel Hill, NC USA..
    Hebert, Michael
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    Fleeman, Renee
    Univ S Florida, Dept Cell Biol Microbiol & Mol Biol, Tampa, FL USA..
    Adams, Jessie
    Univ S Florida, Dept Cell Biol Microbiol & Mol Biol, Tampa, FL USA..
    Jamil, Amer
    Univ Agr Faisalabad, Dept Biochem, Faisalabad, Pakistan..
    Madera, Laurence
    Dalhousie Univ, Dept Pathol, Halifax, NS, Canada..
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Liu, Yufeng
    Univ North Carolina Chapel Hill, Dept Biostat, Dept Genet, Dept Stat & Operat Res, Chapel Hill, NC USA.;Univ North Carolina Chapel Hill, Carolina Ctr Genome Sci, Chapel Hill, NC USA..
    Hoskin, David W.
    Dalhousie Univ, Dept Pathol, Halifax, NS, Canada..
    Shaw, Lindsey N.
    Univ S Florida, Dept Cell Biol Microbiol & Mol Biol, Tampa, FL USA..
    Hicks, Leslie M.
    Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC USA..
    The "PepSAVI-MS" Pipeline for Natural Product Bioactive Peptide Discovery2017In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 89, no 2, p. 1194-1201Article in journal (Refereed)
    Abstract [en]

    The recent increase in extensively drug-resistant bacterial pathogens and the associated increase of morbidity and mortality demonstrate the immediate need for new antibiotic backbones with novel mechanisms of action. Here, we report the development of the PepSAVI-MS pipeline for bioactive peptide discovery. This highly versatile platform employs mass spectrometry and statistics to identify bioactive peptide targets from complex biological samples. We validate the use of this platform through the successful identification of known bioactive peptides from a botanical species, Viola odorata. Using this pipeline, we have widened the known antimicrobial spectrum for V. odorata cyclotides, including antibacterial activity of cycloviolacin O2 against A. baumannii. We further demonstrate the broad applicability of the platform through the identification of novel anticancer activities for cycloviolacins by their cytotoxicity against ovarian, breast, and prostate cancer cell lines.

  • 15.
    Mohotti, S.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi. Univ Colombo, Fac Sci, Dept Chem, Thurstan Rd, Colombo 00300, Sri Lanka..
    Rajendran, S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Muhammad, Taj
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Burman, R.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Hellman, Björn
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    de Silva, E. D.
    Univ Colombo, Fac Sci, Dept Chem, Thurstan Rd, Colombo 00300, Sri Lanka..
    Goransson, U.
    Univ Colombo, Fac Sci, Dept Chem, Thurstan Rd, Colombo 00300, Sri Lanka..
    Hettiarachchi, C. M.
    Univ Colombo, Fac Sci, Dept Chem, Thurstan Rd, Colombo 00300, Sri Lanka..
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    A bioactivity-guided screening of Sri Lankan plants in the search for novel antibacterial and anticancer agents2016In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 82Article in journal (Other academic)
  • 16.
    Muhammad, Taj
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Engineering Of A Minimalized Domain Derived From Human Host Defense Peptide LL-37 Into A Stable And Potent Antimicrobial Drug Lead2016In: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 22, no S2, p. S184-S186Article in journal (Other academic)
  • 17.
    Muhammad, Taj
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Engineering of KR-12: A minimalized domain derived from human host defense peptide LL-37 into a potent antimicrobial drug lead2016In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 82Article in journal (Other academic)
  • 18.
    Nyström, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Al-Rammahi, Noor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Malekkhaiat Häffner, Sara
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Browning, Kathryn L.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Avidin-biotin cross-linked microgel multilayers as carriers for antimicrobial peptides2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 12, p. 4691-4702Article in journal (Refereed)
    Abstract [en]

    Herein, we report on the formation of cross-linked antimicrobial peptide-loaded microgel multilayers. Poly(ethyl acrylate- co-methacrylic acid) microgels were synthesized and functionalized with biotin to enable the formation of microgel multilayers cross-linked with avidin. Microgel functionalization and avidin cross-linking were verified with infrared spectroscopy, dynamic light scattering, and z-potential measurements, while multilayer formation (up to four layers) was studied with null ellipsometry and quartz crystal microbalance with dissipation (QCM-D). Incorporation of the antimicrobial peptide KYE28 (KYEITTIHNLFRKLTHRLFRRNFGYTLR) into the microgel multilayers was achieved either in one shot after multilayer formation or through addition after each microgel layer deposition. The latter was found to strongly promote peptide incorporation. Further, antimicrobial properties of the peptide-loaded microgel multilayers against Escherichia coli were investigated and compared to those of a peptide-loaded microgel monolayer. Results showed a more pronounced suppression in bacterial viability in suspension for the microgel multilayers. Correspondingly, LIVE/DEAD staining showed promoted disruption of adhered bacteria for the KYE28-loaded multilayers. Taken together, cross-linked microgel multilayers thus show promise as high load surface coatings for antimicrobial peptides.

  • 19.
    Nyström, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Nordström, Randi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Saunders, Brian
    Univ Manchester, Manchester, Lancs, England.
    Alvarez-Asencio, Ruben
    KTH, Div Surface Corros Chem, Stockholm, Sweden.
    Rutland, Mark
    KTH, Div Surface Corros Chem, Stockholm, Sweden.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Peptide-loaded microgels as antimicrobial surface coatings2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 20.
    Nyström, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Schmidtchen, Artur
    Lund University, Lund, Sweden; University of Copenhagen, Copenhagen, Denmark.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. University of Copenhagen, Copenhagen, Denmark.
    Peptide-Loaded Microgels as Antimicrobial and Anti-Inflammatory Surface Coatings2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 8, p. 3456-3466Article in journal (Refereed)
    Abstract [en]

    Here we report on covalently immobilized poly(ethyl acrylate- co-methacrylic acid) microgels loaded with the host defense peptide KYE28 (KYEITTIHNLFRKLTHRLFRRNFGYTLR), which is derived from human heparin cofactor II, as well as its poly(ethylene glycol)-conjugated (PEGylated) version, KYE28PEG. Peptide loading and release, as well as the consequences of these processes on the microgel and peptide properties, were studied by in situ ellipsometry, confocal microscopy, zeta potential measurements, and circular dichroism spectroscopy. The results show that the microgel-peptide interactions are electrostatically dominated, thus promoted at higher microgel charge density, while PEGylation suppresses peptide binding. PEGylation also enhances the α-helix induction observed for KYE28 upon microgel incorporation. Additionally, peptide release is facilitated at physiological salt concentration, particularly so for KYE28PEG, which illustrates the importance of electrostatic interactions. In vitro studies on Escherichia coli show that the microgel-modified surfaces display potent antifouling properties in both the absence and presence of the incorporated peptide. While contact killing dominates at low ionic strength for the peptide-loaded microgels, released peptides also provide antimicrobial activity in bulk at a high ionic strength. Additionally, KYE28- and KYE28PEG-loaded microgels display anti-inflammatory effects on human monocytes. Taken together, these results not only show that surface-bound microgels offer an interesting approach for local drug delivery of host defense peptides but also illustrate the need to achieve high surface loads of peptides for efficient biological effects.

  • 21.
    Park, Sungkyu
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Cyclotide Structure-Activity Relationships: Qualitative and Quantitative Approaches Linking Cytotoxic and Anthelmintic Activity to the Clustering of Physicochemical Forces2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 3, p. e91430-Article in journal (Refereed)
    Abstract [en]

    Cyclotides are a family of plant-derived proteins that are characterized by a cyclic backbone and a knotted disulfide topology. Their cyclic cystine knot (CCK) motif makes them exceptionally resistant to thermal, chemical, and enzymatic degradation. Cyclotides exert much of their biological activity via interactions with cell membranes. In this work, we qualitatively and quantitatively analyze the cytotoxic and anthelmintic membrane activities of cyclotides. The qualitative and quantitative models describe the potency of cyclotides using four simple physicochemical terms relevant to membrane contact. Specifically, surface areas of the cyclotides representing lipophilic and hydrogen bond donating properties were quantified and their distribution across the molecular surface was determined. The resulting quantitative structure-activity relation (QSAR) models suggest that the activity of the cyclotides is proportional to their lipophilic and positively charged surface areas, provided that the distribution of these surfaces is asymmetric. In addition, we qualitatively analyzed the physicochemical differences between the various cyclotide subfamilies and their effects on the cyclotides' orientation on the membrane and membrane activity.

  • 22.
    Raschig, Judith
    et al.
    Univ Hosp Tuebingen, Internal Med 1, Tubingen, Germany..
    Mailaender-Sanchez, Daniela
    Univ Hosp Tuebingen, Internal Med 1, Tubingen, Germany..
    Berscheid, Anne
    Univ Tubingen, Interfac Inst Microbiol & Infect Med, Dept Microbial Bioact Cpds, Tubingen, Germany..
    Berger, Juergen
    Max Planck Inst Dev Biol, Electron Microscopy, Tubingen, Germany..
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Courth, Lioba F.
    Univ Hosp Tuebingen, Internal Med 1, Tubingen, Germany..
    Malek, Nisar P.
    Univ Hosp Tuebingen, Internal Med 1, Tubingen, Germany..
    Broetz-Oesterhelt, Heike
    Univ Tubingen, Interfac Inst Microbiol & Infect Med, Dept Microbial Bioact Cpds, Tubingen, Germany..
    Wehkamp, Jan
    Univ Hosp Tuebingen, Internal Med 1, Tubingen, Germany..
    Ubiquitously expressed Human Beta Defensin 1 (hBD1) forms bacteria-entrapping nets in a redox dependent mode of action2017In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 13, no 3, article id e1006261Article in journal (Refereed)
    Abstract [en]

    Ever since the discovery of endogenous host defense antimicrobial peptides it has been discussed how these evolutionary conserved molecules avoid to induce resistance and to remain effective. Human beta-defensin 1 (hBD1) is an ubiquitously expressed endogenous antimicrobial peptide that exhibits qualitatively distinct activities between its oxidized and reduced forms. Here, we explore these antimicrobial mechanisms. Surprisingly, using electron microscopy we detected a so far unknown net-like structure surrounding bacteria, which were treated with the reduced but not the oxidized form of hBD1. A transmigration assay demonstrated that hBD1-derived nets capture bacteria and inhibit bacterial transmigration independent of bacterial killing. The presence of nets could completely prevent migration of hBD1 resistant pathogens and are stable in the presence of human duodenal secretion with a high amount of proteases. In contrast to HD6, cysteins are necessary for net formation. This redox-dependent function serves as an additional mechanism of action for hBD1 and differs from net formation by other defensins such as Paneth cell-derived human alpha-defensin 6 (HD6). While hBD1red and hBD1ox have distinct antimicrobial profiles and functions, only the reduced form provides additional host protection by entrapping bacteria in extracellular net structures preventing bacterial invasion. Better understanding of the modes of action of endogenous host peptides will help to find new antimicrobial strategies.

  • 23. Shcherbakova, A.
    et al.
    Boldbaatar, Delgerbat
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Koptina, Anna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bioassay-guided fractionation of acetonitrile extract from Evernia prinastri (L.) Ach.2014In: Phytopharm 2014, Saint-Petersburg, Russia 3-5 July 2014 / [ed] Shabanov P.D., Saint-Petersburg, Russia, 2014, Vol. 12, p. 59-60Conference paper (Refereed)
  • 24.
    Slazak, Blazej
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi. Polish Acad Sci, W Szafer Inst Bot, Krakow, Poland.
    Kapusta, Malgorzata
    Univ Gdansk, Fac Biol, Dept Plant Cytol & Embryol, Gdansk, Poland.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Slomka, Aneta
    Jagiellonian Univ, Inst Bot, Dept Plant Cytol & Embryol, Gdansk, Poland.
    Krychowiak, Marta
    Univ Gdansk, Intercollegiate Fac Biotechnol, Lab Biol Act Cpds, Gdansk, Poland;Med Univ Gdansk, Gdansk, Poland.
    Shariatgorji, Mohammadreza
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Andrén, Per E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bohdanowicz, Jerzy
    Univ Gdansk, Fac Biol, Dept Plant Cytol & Embryol, Gdansk, Poland.
    Kuta, Elzbieta
    Jagiellonian Univ, Inst Bot, Dept Plant Cytol & Embryol, Gdansk, Poland.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    How Does the Sweet Violet (Viola odorata L.) Fight Pathogens and Pests - Cyclotides as a Comprehensive Plant Host Defense System2018In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, article id 1296Article in journal (Refereed)
    Abstract [en]

    Cyclotides are cyclic plant polypeptides of 27-37 amino acid residues. They have been extensively studied in bioengineering and drug development contexts. However, less is known about the relevance of cyclotides for the plants producing them. The anti-insect larvae effects of kB1 and antibacterial activity of cyO2 suggest that cyclotides are a part of plant host defense. The sweet violet (Viola odorata L.) produces a wide array of cyclotides, including kB1 (kalata B1) and cyO2 (cycloviolacin O2), with distinct presumed biological roles. Here, we evaluate V. odorata cyclotides' potency against plant pathogens and their mode of action using bioassays, liposome experiments and immunogold labeling for transmission electron microscopy (TEM). We explore the link between the biological activity and distribution in plant generative, vegetative tissues and seeds, depicted by immunohistochemistry and matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI). Cyclotides cyO2, cyO3, cyO13, and cyO19 are shown to have potent activity against model fungal plant pathogens (Fusarium oxysporum, F. graminearum, F. culmorum, Mycosphaerella fragariae, Botrytis cinerea) and fungi isolated from violets (Colletotrichum utrechtense and Alternaria alternata), with minimal inhibitory concentrations (MICs) ranging from 0.8 to 25 mu M. Inhibition of phytopathogenic bacteria - Pseudomonas syringae pv. syringae, Dickeya dadantii and Pectobacterium atrosepticum - is also observed with MIC = 25-100 mu M. A membrane-disrupting antifungal mode of action is shown. Finding cyO2 inside the fungal spore cells in TEM images may indicate that other, intracellular targets may be involved in the mechanism of toxicity. Fungi can not break down cyclotides in the course of days. varv A (kalata S) and kB1 show little potency against pathogenic fungi when compared with the tested cycloviolacins. cyO2, cyO3, cyO19 and kB1 are differentially distributed and found in tissues vulnerable to pathogen (epidermis, rizodermis, vascular bundles, protodermis, procambium, ovary walls, outer integuments) and pest ( ground tissues of leaf and petiole) attacks, respectively, indicating a link between the cyclotides' sites of accumulation and biological role. Cyclotides emerge as a comprehensive defense system in V. odorata, in which different types of peptides have specific targets that determine their distribution in plant tissues.

  • 25.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Felth, Jenny
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bohlin, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bioassays in Natural Product Research: Strategies and Methods in the Search for Anti-inflammatory and Antimicrobial Activity2014In: Phytochemical Analysis, ISSN 0958-0344, E-ISSN 1099-1565, Vol. 25, no 1, p. 13-28Article, review/survey (Refereed)
    Abstract [en]

    Introduction: Identifying bioactive molecules from complex biomasses requires careful selection and execution of relevant bioassays in the various stages of the discovery process of potential leads and targets.

    Objective: The aim of this review is to share our long-term experience in bioassay-guided isolation, and mechanistic studies, of bioactive compounds from different organisms in nature with emphasis on anti-inflammatory and antimicrobial activity.

    Methods: In the search for anti-inflammatory activity, in vivo and in vitro model combinations with enzymes and cells involved in the inflammatory process have been used, such as cyclooxygenases, human neutrophils and human cancer cell lines. Methods concerning adsorption and perforation of bacteria, fungi, human cells and model membranes, have been developed and optimised, with emphasis on antimicrobial peptides and their interaction with the membrane target, in particular their ability to distinguish host from pathogen.

    Results: A long-term research has provided experience of selection and combination of bioassay models, which has led to an increased understanding of ethnopharmacological and ecological observations, together with in-depth knowledge of mode of action of isolated compounds.

    Conclusion: A more multidisciplinary approach and a higher degree of fundamental research in development of bioassays are often necessary to identify and to fully understand the mode of action of bioactive molecules with novel structure-activity relationships from natural sources. 

    Selection and execution of relevant bioassays are critical in the various stages of the discovery process of potential drug leads and targets from natural sources. The aim of this review is to share our long-term experience in bioassay-guided isolation of bioactive compounds from different organisms in nature with emphasis on anti-inflammatory and antimicrobial activity. We conclude that an increased multidisciplinary approach and a higher degree of fundamental research in development of bioassays are essential to discover complex structure-activity relationships.

  • 26.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Kristiansen, Per Eugen
    Univ Oslo, Dept Mol Biosci, Box 1041, N-0316 Oslo, Norway.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Grob, Nathalie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Skjeldal, Lars
    Norwegian Univ Life Sci, Dept Chem Biochem & Food Sci, N-1432 As, Norway.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Selective membrane disruption by the cyclotide kalata B7: complex ions and essential functional groups in the phosphatidylethanolamine binding pocket2016In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1858, no 6, p. 1317-1327Article in journal (Refereed)
    Abstract [en]

    The cyclic cystine knot plant peptides called cyclotides are active against a wide variety of organisms. This is primarily achieved through membrane binding and disruption, in part deriving from a high affinity for phosphatidylethanolamine (PE) lipids. Some cyclotides, such as kalata B7 (kB7), form complexes with divalent cations in a pocket associated with the tyrosine residue at position 15 (Tyr15). In the current work we explore the effect of cations on membrane leakage caused by cyclotides kB1, kB2 and kB7, and we identify a functional group that is essential for PE selectivity. The presence of PE-lipids in liposomes increased the membrane permeabilizing potency of the cyclotides, with the potency of kB7 increasing by as much as 740-fold. The divalent cations Mn(2+), Mg(2+) and Ca(2+) had no apparent effect on PE selectivity. However, amino acid substitutions in kB7 proved that Tyr15 is crucial for PE-selective membrane permeabilization on various liposome systems. Although the tertiary structure of kB7 was maintained, as reflected by the NMR solution structure, mutating Tyr into Ser at position 15 resulted in substantially reduced PE selectivity. Ala substitution at the same position produced a similar reduction in PE selectivity, while substitution with Phe maintained high selectivity. We conclude that the phenyl ring in Tyr15 is critical for the high PE selectivity of kB7. Our results suggest that PE-binding and divalent cation coordination occur in the same pocket without adverse effects of competitive binding for the phospholipid.

  • 27.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Park, Sungkyu
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Burman, Robert
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bactericidal activity of cyclotides where phosphatidylethanolamine-lipid selectivity determines antimicrobial spectra2017In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1859, no 10, p. 1986-2000Article in journal (Refereed)
    Abstract [en]

    Cyclotides are a family of plant peptides characterized by a cystine knot embedded in a macrocyclic backbone. They bind to and disrupt phospholipid membranes, which explain their lytic activity on cells. In this study, we expose the full antibacterial potency of cyclotides by avoiding its inhibition by rich growth media assay conditions. For that purpose a two-step microdilution assay protocol was developed, using non-growing conditions during initial peptide incubation. A diverse set of cyclotides was tested for antibacterial and antifungal activity, and the results show that most cyclotides are active under these conditions, especially against Gram-negative bacteria. Activity was observed at sub-micromolar concentrations for three of the cyclotides tested, surpassing that of the control peptides LL-37 and melittin. Noteworthy, two anionic cyclotides were active on Pseudomonas aeruginosa at low micromolar concentrations. Broad-spectrum activity was pronounced among cycloviolacin cyclotides, which included activity on Staphylococcus aureus and Candida albicans. The factors influencing their bactericidal spectrum were revealed by correlating antimicrobial activity with membrane permeabilization on various liposome systems and with the physiochemical properties of the cyclotides. Whereas general electrostatic and hydrophobic parameters are more important for broad-spectrum cyclotides; a phospholipid-specific mechanism of membrane permeabilization, through interaction with phosphatidylethanolamine-lipids, is essential for cyclotides active primarily on Gram-negative bacteria.

  • 28.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Pasupuleti, Mukesh
    Schmidtchen, Artur
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Evaluation of strategies for improving proteolytic resistance of antimicrobial peptides by using variants of EFK17, an internal segment of LL-372009In: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 53, no 2, p. 593-602Article in journal (Refereed)
    Abstract [en]

    Methods for increasing the proteolytic stability of EFK17 (EFKRIVQRIKDFLRNLV), a new peptide sequence with antimicrobial properties derived from LL-37, were evaluated. EFK17 was modified by four d-enantiomer or tryptophan (W) substitutions at known protease cleavage sites as well as by terminal amidation and acetylation. The peptide variants were studied in terms of proteolytic resistance, antibacterial potency, and cytotoxicity but also in terms their adsorption at model lipid membranes, liposomal leakage generation, and secondary-structure behavior. The W substitutions resulted in a marked reduction in the proteolytic degradation caused by human neutrophil elastase, Staphylococcus aureus aureolysin, and V8 protease but not in the degradation caused by Pseudomonas aeruginosa elastase. For the former two endoproteases, amidation and acetylation of the terminals also reduced proteolytic degradation but only when used in combination with W substitutions. The d-enantiomer substitutions rendered the peptides indigestible by all four proteases; however, those peptides displayed little antimicrobial potency. The W- and end-modified peptides, on the other hand, showed an increased bactericidal potency compared to that of the native peptide sequence, coupled with a moderate cytotoxicity that was largely absent in serum. The bactericidal, cytotoxic, and liposome lytic properties correlated with each other as well as with the amount of peptide adsorbed at the lipid membrane and the extent of helix formation associated with the adsorption. The lytic properties of the W-substituted peptides were less impaired by increased ionic strength, presumably by a combination of W-mediated stabilization of the largely amphiphilic helix conformation and a nonelectrostatic W affinity for the bilayer interface. Overall, W substitutions constitute an interesting means to reduce the proteolytic susceptibility of EFK17 while also improving antimicrobial performance.

  • 29.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Pasupuleti, Mukesh
    Department of Clinical Sciences, Lund University.
    Schmidtchen, Artur
    Department of Clinical Sciences, Lund University.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Oligotryptophan-tagged antimicrobial peptides and the role of the cationic sequence2009In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1788, no 9, p. 1916-1923Article in journal (Refereed)
    Abstract [en]

    The effects of varying the cationic sequence of oligotryptophan-tagged antimicrobial peptides were investigated in terms of peptide adsorption to model lipid membranes, liposome leakage induction, and antibacterial potency. Heptamers of lysine (K7) and arginine (R7) were lytic against Escherichia coli bacteria at low ionic strength. In parallel, both peptides adsorbed on to bilayers formed by E. coli phospholipids, and caused leakage in the corresponding liposomes. K7 was the more potent of the two peptides in causing liposome leakage, although the adsorption of this peptide on E. coli membranes was lower than that of R7. The bactericidal effect, liposome lysis, and membrane adsorption were all substantially reduced at physiological ionic strength. When a tryptophan pentamer tag was linked to the C-terminal end of these peptides, substantial peptide adsorption, membrane lysis, and bacterial killing was observed also at high ionic strength, and also for a peptide of lower cationic charge density (KNKGKKN-W5). Strikingly, the order of membrane lytic potential of the cationic peptides investigated was reversed when tagged. This and other aspects of peptide behavior and adsorption, in conjunction with effects on liposomes and bacteria, suggest that tagged and untagged peptides act by different lytic mechanisms, which to some extent counterbalance each other. Thus, while the untagged peptides act by generating negative curvature strain in the phospholipid membrane, the tagged peptides cause positive curvature strain. The tagged heptamer of arginine, R7W5, was the best candidate for E. coli membrane lysis at physiological salt conditions and proved to be an efficient antibacterial agent.

  • 30.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Ringstad, Lovisa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Schmidtchen, Artur
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Interaction between amphiphilic peptides and phospholipid membranes2010In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 15, no 6, p. 467-478Article, review/survey (Refereed)
    Abstract [en]

    This brief review aims at providing some illustrative examples on the interaction between amphiphilic peptides and phospholipid membranes an area of significant current interest Focusing on antimicrobial peptides factors affecting peptide-membrane interactions are addressed including effects of peptide length charge hydrophobicity secondary structure and topology Effects of membrane composition are also illustrated including effects of membrane charge nature of the polar headgroup and presence of cholesterol and other sterols Throughout novel insights on the importance of peptide adsorption density on membrane stability are emphasized as is the correlation between peptide adsorption peptide induced leakage in model liposome systems peptide-induced lysis of bacteria and bacteria killing.

  • 31.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Vikeved, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Cárdenas, Paco
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Alsmark, Cecilia
    Uppsala University.
    Chen, Yung Hsuan
    National Museum of Marine Biology and Aquarium.
    Backlund, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Aaptamines from Haliclona and bromopyrroles from Agelas — marine sponge alkaloids with distinct modes of action against bacteria and protozoaManuscript (preprint) (Other academic)
  • 32.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Wessman, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Ringstad, Lovisa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Effect of lipid headgroup composition on the interaction between melittin and lipid bilayers2007In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 311, no 1, p. 59-69Article in journal (Refereed)
    Abstract [en]

    The effect of the lipid polar headgroup on melittin-phospholipid interaction was investigated by cryo-TEM, fluorescence spectroscopy, ellipsometry, CD, electrophoresis and photon correlation spectroscopy. In particular, focus was placed on the effect of the lipid polar headgroup on peptide adsorption to, and penetration into, the lipid bilayer, as well as on resulting colloidal stability effects for large unilamellar liposomes. The effect of phospholipid headgroup properties on melittin-bilayer interaction was addressed by comparing liposomes contg. phosphatidylcholine, -acid, and -inositol at varying ionic strength. Increasing the bilayer neg. charge leads to an increased liposome tolerance toward melittin which is due to an electrostatic arrest of melittin at the membrane interface. Balancing the electrostatic attraction between the melittin pos. charges and the phospholipid neg. charges through a hydration repulsion, caused by inositol, reduced this surface arrest and increased liposome susceptibility to the disruptive actions of melittin. Furthermore, melittin was demonstrated to induce liposome structural destabilization on a colloidal scale which coincided with leakage induction for both anionic and zwitterionic systems. The latter findings thus clearly show that coalescence, aggregation, and fragmentation contribute to melittin-induced liposome leakage, and that detailed mol. analyses of melittin pore formation are incomplete without considering also these colloidal aspects.

  • 33.
    Svahn, K. Stefan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Goransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    El-Seedi, Hesham
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bohlin, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Larsson, D. G. J.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Olsen, Björn
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Chryssanthou, E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    The search for new antibiotic substances from filamentous fungi2012In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 78, no 11, p. 1162-1162Article in journal (Other academic)
  • 34.
    Svahn, Stefan K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Chryssanthou, Erja
    Olsen, Björn
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
    Sjölin, Jan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
    Stromstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Induction of Gliotoxin Secretion in Aspergillus fumigatus by Bacteria-Associated Molecules2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 4, p. e93685-Article in journal (Refereed)
    Abstract [en]

    Aspergillus fumigatus is the most common causative agent of mold diseases in humans, giving rise to life-threatening infections in immunocompromised individuals. One of its secreted metabolites is gliotoxin, a toxic antimicrobial agent. The aim of this study was to determine whether the presence of pathogen-associated molecular patterns in broth cultures of A. fumigatus could induce gliotoxin production. Gliotoxin levels were analyzed by ultra-performance liquid chromatography and mass spectrometry. The presence of a bacteria-derived lipopolysaccharide, peptidoglycan, or lipoteichoic acid in the growth media at a concentration of 5 mu g/ml increased the gliotoxin concentration in the media by 37%, 65%, and 35%, respectively. The findings reveal a correlation between the concentrations of pathogen-associated molecular patterns and gliotoxin secretion. This shows that there is a yet uncharacterized detection system for such compounds within fungi. Inducing secondary metabolite production by such means in fungi is potentially relevant for drug discovery research. Our results also give a possible explanation for the increased virulence of A. fumigatus during bacterial co-infection, one that is important for the transition from colonization to invasiveness in this pulmonary disease.

  • 35.
    Wessman, Per
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Strömstedt, Adam A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Melittin-lipid bilayer interactions and the role of cholesterol2008In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 95, no 9, p. 4324-4336Article in journal (Refereed)
    Abstract [en]

    The membrane-destabilizing effect of the peptide melittin on phosphatidylcholine membranes is modulated by the presence of cholesterol. This investigation shows that inclusion of 40 mol % cholesterol in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine or 1,2-dioleoyl-sn-glycero-3-phosphocholine liposomes reduces melittin's affinity for the membrane. It is significant that the presence of cholesterol does not increase the amount of membrane-associated melittin needed to cause maximum leakage from, or major structural rearrangements of, the liposomes. Furthermore, comparison of microscopy and leakage data suggests that melittin-induced leakage occurs via different mechanisms in the cholesterol-free and cholesterol-supplemented systems. In the absence of cholesterol, leakage of carboxyfluorescein takes place from intact liposomes in a manner compatible with the presence of small melittin-induced pores. In the presence of cholesterol, on the other hand, adsorption of the peptide causes complete membrane disruption and the formation of long-lived open-bilayer structures. Moreover, in the case of cholesterol-supplemented systems, melittin induces pronounced liposome aggregation. Cryotransmission electron microscopy was used, together with ellipsometry, circular dichroism, turbidity, and leakage measurements, to investigate the effects of melittin on phosphatidylcholine membranes in the absence and presence of cholesterol. The melittin partitioning behavior in the membrane systems was estimated by means of steady-state fluorescence spectroscopy measurements.

1 - 35 of 35
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf