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  • 1.
    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.

  • 2.
    Aboye, Teshome Leta
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Clark, Richard J.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. 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. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Roig, Marta Bajona
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Craik, David J.
    University of Queensland, Institute for Molecular Bioscience.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Interlocking disulfides in circular proteins: toward efficient oxidative folding of cyclotides.2011In: Antioxidants and Redox Signaling, ISSN 1523-0864, E-ISSN 1557-7716, Vol. 14, no 1, p. 77-86Article in journal (Refereed)
    Abstract [en]

    Cyclotides are ultrastable plant proteins characterized by the presence of a cyclic amide backbone and three disulfide bonds that form a cystine knot. Because of their extreme stability, there has been significant interest in developing these molecules as a drug design scaffold. For this potential to be realized, efficient methods for the synthesis and oxidative folding of cyclotides need to be developed, yet we currently have only a basic understanding of the folding mechanism and the factors influencing this process. In this study, we determine the major factors influencing oxidative folding of the different subfamilies of cyclotides. The folding of all the cyclotides examined was heavily influenced by the concentration of redox reagents, with the folding rate and final yield of the native isomer greatly enhanced by high concentrations of oxidized glutathione. Addition of hydrophobic solvents to the buffer also enhanced the folding rates and appeared to alter the folding pathway. Significant deamidation and isoaspartate formation were seen when oxidation conditions were conducive to slow folding. The identification of factors that influence the folding and degradation pathways of cyclotides will facilitate the development of folding screens and optimized conditions for producing cyclotides and grafted analogs as stable peptide-based therapeutics.

  • 3.
    Andersson, H. S.
    et al.
    Linnaeus Univ, Ctr Biomat Chem, Dept Chem & Biomed Sci, Norra Vagen 49, S-39234 Kalmar, Sweden..
    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.
    Hedstrom, M.
    Lund Univ, Dept Biotechnol, Box 118, S-22100 Lund, Sweden..
    Seth, H.
    Univ Gothenburg, Dept Biol & Environm Sci, Box 463, S-40530 Gothenburg, Sweden..
    Sundberg, P.
    Univ Gothenburg, Dept Biol & Environm Sci, Box 463, S-40530 Gothenburg, Sweden..
    Rosengren, K. J.
    Univ Queensland, Sch Biomed Sci, Brisbane, Qld 4072, Australia..
    Strand, M.
    Univ Gothenburg, Dept Biol & Environm Sci, Box 463, S-40530 Gothenburg, Sweden.;Swedish Univ Agr Sci, Swedish Species Informat Ctr, Backlosavagen 10, S-75651 Uppsala, Sweden..
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    The toxicity of ribbon worms: Alpha-nemertides or tetrodotoxin, or both?2016In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 82Article in journal (Other academic)
  • 4.
    Anwar, J.
    et al.
    Univ Agr, Dept Agr Chem, Peshawar 25100, Pakistan..
    Muhammad, Taj
    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.
    Iqbal, Z.
    Univ Agr, Dept Agr Chem, Peshawar 25100, Pakistan..
    Fungi as a source for antibacterial compounds2016In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 82Article in journal (Other academic)
  • 5. Arnison, Paul G.
    et al.
    Bibb, Mervyn J.
    Bierbaum, Gabriele
    Bowers, Albert A.
    Bugni, Tim S.
    Bulaj, Grzegorz
    Camarero, Julio A.
    Campopiano, Dominic J.
    Challis, Gregory L.
    Clardy, Jon
    Cotter, Paul D.
    Craik, David J.
    Dawson, Michael
    Dittmann, Elke
    Donadio, Stefano
    Dorrestein, Pieter C.
    Entian, Karl-Dieter
    Fischbach, Michael A.
    Garavelli, John S.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gruber, Christian W.
    Haft, Daniel H.
    Hemscheidt, Thomas K.
    Hertweck, Christian
    Hill, Colin
    Horswill, Alexander R.
    Jaspars, Marcel
    Kelly, Wendy L.
    Klinman, Judith P.
    Kuipers, Oscar P.
    Link, A. James
    Liu, Wen
    Marahiel, Mohamed A.
    Mitchell, Douglas A.
    Moll, Gert N.
    Moore, Bradley S.
    Mueller, Rolf
    Nair, Satish K.
    Nes, Ingolf F.
    Norris, Gillian E.
    Olivera, Baldomero M.
    Onaka, Hiroyasu
    Patchett, Mark L.
    Piel, Joern
    Reaney, Martin J. T.
    Rebuffat, Sylvie
    Ross, R. Paul
    Sahl, Hans-Georg
    Schmidt, Eric W.
    Selsted, Michael E.
    Severinov, Konstantin
    Shen, Ben
    Sivonen, Kaarina
    Smith, Leif
    Stein, Torsten
    Suessmuth, Roderich D.
    Tagg, John R.
    Tang, Gong-Li
    Truman, Andrew W.
    Vederas, John C.
    Walsh, Christopher T.
    Walton, Jonathan D.
    Wenzel, Silke C.
    Willey, Joanne M.
    van der Donk, Wilfred A.
    Ribosomally synthesized and post-translationally modified peptide natural products: overview and recommendations for a universal nomenclature2013In: Natural product reports (Print), ISSN 0265-0568, E-ISSN 1460-4752, Vol. 30, no 1, p. 108-160Article, review/survey (Refereed)
    Abstract [en]

    This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed.

  • 6.
    Bohlin, Lars
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Alsmark, Cecilia
    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.
    Klum, M.
    Weden, Christina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Backlund, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Strategies and methods for a sustainable search for bioactive compounds2012In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 78, no 11, p. 1031-1032Article in journal (Other academic)
  • 7.
    Bohlin, Lars
    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.
    Alsmark, Cecilia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Wedén, Christina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Backlund, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Natural products in modern life science2010In: Phytochemistry Reviews, ISSN 1568-7767, E-ISSN 1572-980X, Vol. 9, no 2, p. 279-301Article in journal (Refereed)
    Abstract [en]

    With a realistic threat against biodiversity in rain forests and in the sea, a sustainable use of natural products is becoming more and more important. Basic research directed against different organisms in Nature could reveal unexpected insights into fundamental biological mechanisms but also new pharmaceutical or biotechnological possibilities of more immediate use. Many different strategies have been used prospecting the biodiversity of Earth in the search for novel structure-activity relationships, which has resulted in important discoveries in drug development. However, we believe that the development of multidisciplinary incentives will be necessary for a future successful exploration of Nature. With this aim, one way would be a modernization and renewal of a venerable proven interdisciplinary science, Pharmacognosy, which represents an integrated way of studying biological systems. This has been demonstrated based on an explanatory model where the different parts of the model are explained by our ongoing research. Anti-inflammatory natural products have been discovered based on ethnopharmacological observations, marine sponges in cold water have resulted in substances with ecological impact, combinatory strategy of ecology and chemistry has revealed new insights into the biodiversity of fungi, in depth studies of cyclic peptides (cyclotides) has created new possibilities for engineering of bioactive peptides, development of new strategies using phylogeny and chemography has resulted in new possibilities for navigating chemical and biological space, and using bioinformatic tools for understanding of lateral gene transfer could provide potential drug targets. A multidisciplinary subject like Pharmacognosy, one of several scientific disciplines bridging biology and chemistry with medicine, has a strategic position for studies of complex scientific questions based on observations in Nature. Furthermore, natural product research based on intriguing scientific questions in Nature can be of value to increase the attraction for young students in modern life science.

  • 8.
    Bohlin, Lars
    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.
    Backlund, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Modern pharmacognosy: Connecting biology and chemistry2007In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 79, no 4, p. 763-774Article in journal (Refereed)
    Abstract [en]

    In many countries today, the number of students selecting chemistry for higher studies is decreasing. At the same time, interest in the environmental aspects of chemistry, green chemistry, and sustainable use of natural products is increasing among the young generation of students. By modernizing and renewing a venerable proven science, pharmacognosy would have a strategic position to connect biology and chemistry. This multidisciplinary subject is important for discovery of novel and unique molecules with drug potential, and for revealing unknown targets, by studying evolutionary structure-activity optimization in nature. In this paper, the overall aim and strategies of our research are presented and exemplified by three different research projects.

    Natural products are involved in scientific issues important for a sustainable society, and a multidisciplinary subject such as pharmacognosy can, therefore, be useful in increasing future interest in both chemistry and biology.

  • 9.
    Boldbaatar, Delgerbat
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    El-Seedi, Hesham R.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Findakly, Meriana
    Jabri, Safa
    Javzan, Batkhuu
    Choidash, Battsetseg
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Hellman, Bjorn
    Antigenotoxic and antioxidant effects of the Mongolian medicinal plant Leptopyrum fumarioides (L): An in vitro study2014In: Journal of Ethnopharmacology, ISSN 0378-8741, E-ISSN 1872-7573, Vol. 155, no 1, p. 599-606Article in journal (Refereed)
    Abstract [en]

    Ethnopharmacological relevance: Leptopyrum fumarioides has been used in the traditional medicine of Mongolia for the treatment of various diseases, including drug intoxications. However, since there is only sparse information about its chemistry, active components, and pharmacological and toxicological effects, the major aim of the present study employing mouse lymphoma cells was to evaluate the genotoxic and antigenotoxic/antioxidative effects of extracts and components isolated from this plant. Material and methods: A crude methanol extract was separated into three different sub-extracts: dichloromethane, n-butanol, and water. The major constituent of the n-butanol extract, i.e., the flavone luteolin-7-O-glucoside and a mixture of the most abundant compounds in the dichloromethane sub-extract were then isolated. DNA damage was evaluated using the comet assay; the antioxidant activity was evaluated using the DPPH radical scavenging assay. Results: The crude methanol extract, the dichloromethane sub-extract and the mixture of compounds isolated from the latter fraction, increased the level of DNA damage after three hours of exposure. In contrast, no increase in DNA damage was observed in the cells that had been exposed to the n-butanol and water sub-extracts, or to the pure flavone. When non-DNA damaging concentrations of extracts and compounds were tested together with the DNA damaging agent catechol, all sub-extracts were found to reduce the catechol-induced DNA damage (the flavone was then found to be the most effective protective agent). The n-butanol sub-extract and the flavone were also found to have the most prominent antioxidative effects. Conclusion: Based on the results from the present study, components in Leptopyrum fumarioides were found to protect the DNA damage induced by catechol, probably by acting as potent antioxidants.

  • 10.
    Boldbaatar, Delgerbat
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Natl Univ Mongolia, Sch Engn & Appl Sci, Ulaanbaatar 46, Mongol Peo Rep..
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    El-Seedi, Hesham R.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Univ Malaya, Fac Sci, Dept Chem, Kuala Lumpur 50603, Malaysia..
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Synthesis, Structural Characterization, and Bioactivity of the Stable Peptide RCB-1 from Ricinus communis2015In: Journal of natural products (Print), ISSN 0163-3864, E-ISSN 1520-6025, Vol. 78, no 11, p. 2545-2551Article in journal (Refereed)
    Abstract [en]

    The Ricinus communis biomarker peptides RCB-1 to -3 comprise homologous sequences of 19 (RCB-1) or 18 (RCB-2 and -3) amino acid residues. They all include four cysteine moieties, which form two disulfide bonds. However, neither the 3D structure nor the biological activity of any of these peptides is known. The synthesis of RCB-1, using microwave-assisted, Fmoc-based solid-phase peptide synthesis, and a method for its oxidative folding are reported. The tertiary structure of RCB-1, subsequently established using solution-state NMR, reveals a twisted loop fold with antiparallel ?-sheets reinforced by the two disulfide bonds. Moreover, RCB-1 was tested for antibacterial, antifungal, and cytotoxic activity, as well as in a serum stability assay, in which it proved to be remarkably stable.

  • 11. Broussalis, Adriana M.
    et al.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Coussio, Jorge D.
    Ferraro, Graciela
    Martino, Virginia
    Claeson, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    First cyclotide from Hybanthus (Violaceae)2001In: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 58, no 1, p. 47-51Article in journal (Refereed)
    Abstract [en]

    Hypa A, a novel macrocyclic polypeptide containing 30 amino acid residues, has been isolated from the n-butanol extract of the Argentine plant Hybanthus parviflorus. The sequence, cyclo-(SCVYIPCTITALLGCSCKNKVCYNGIPCAE), was determined by automated Edman degradation, quantitative amino acid analysis and nanospray MS/MS(2). Three intramolecular disulfide bridges stabilize the cyclic peptide backbone of hypa A. Using these structural features to classify the peptide as a cyclotide, we extended the distribution of that substance class to a new genus, and now propose a uniform nomenclature for cyclotides.

  • 12. Broussalis, Adriana M.
    et al.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Coussio, Jorge D.
    Ferraro, Graciela
    Martino, Virginia
    Claeson, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    First cyclotide from Hybanthus (Violaceae)2001In: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 58, no 1, p. 47-51Article in journal (Refereed)
    Abstract [en]

    Hypa A, a novel macrocyclic polypeptide containing 30 amino acid residues, has been isolated from the n-butanol extract of the Argentine plant Hybanthus parviflorus. The sequence, cyclo-(SCVYIPCTITALLGCSCKNKVCYNGIPCAE), was determined by automated Edman degradation, quantitative amino acid analysis and nanospray MS/MS2. Three intramolecular disulfide bridges stabilize the cyclic peptide backbone of hypa A. Using these structural features to classify the peptide as a cyclotide, we extended the distribution of that substance class to a new genus, and now propose a uniform nomenclature for cyclotides.

  • 13.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gruber, Christian W
    Rizzardi, Kristina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Herrmann, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Craik, David J
    Gupta, Mahabir P
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Cyclotide proteins and precursors from the genus Gloeospermum: filling a blank spot in the cyclotide map of Violaceae2010In: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 71, no 1, p. 13-20Article in journal (Refereed)
    Abstract [en]

    Cyclotides are disulfide-rich plant proteins that are exceptional in their cyclic structure; their N and C termini are joined by a peptide bond, forming a continuous circular backbone, which is reinforced by three interlocked disulfide bonds. Cyclotides have been found mainly in the coffee (Rubiaceae) and violet (Violaceae) plant families. Within the Violaceae, cyclotides seem to be widely distributed, but the cyclotide complements of the vast majority of Violaceae species have not yet been explored. This study provides insight into cyclotide occurrence, diversity and biosynthesis in the Violaceae, by identifying mature cyclotide proteins, their precursors and enzymes putatively involved in their biosynthesis in the tribe Rinoreeae and the genus Gloeospermum. Twelve cyclotides from two Panamanian species, Gloeospermum pauciflorum Hekking and Gloeospermum blakeanum (Standl.) Hekking (designated Glopa A-E and Globa A-G, respectively) were characterised through cDNA screening and protein isolation. Screening of cDNA for the oxidative folding enzymes protein-disulfide isomerase (PDI) and thioredoxin (TRX) resulted in positive hits in both species. These enzymes have demonstrated roles in oxidative folding of cyclotides in Rubiaceae, and results presented here indicate that Violaceae plants have evolved similar mechanisms of cyclotide biosynthesis. We also describe PDI and TRX sequences from a third cyclotide-expressing Violaceae species, Viola biflora L., which further support this hypothesis.

  • 14.
    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.

  • 15.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Herrmann, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Tran, Rosetti
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Kivelä, Jan-Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Lomize, Andrei
    University of Michigan, Little College of Pharmacy.
    Gullbo, Joachim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Pharmacology.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Cytotoxic potency of small macrocyclic knot proteins: Structure-activity and mechanistic studies of native and chemically modified cyclotides2011In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 11, p. 4306-4314Article in journal (Refereed)
    Abstract [en]

    The cyclotides are a family of circular and knotted proteins of natural origin with extreme enzymatic and thermal stability and active in a wide range of biological activities make them promising tools for pharmaceutical and crop-protection applications. The cyclotides are divided into two subfamilies depending on the presence (Möbius) or absence (bracelet) of a cis-Pro peptide bond. In the current work we report a series of experiments to give further insight into the structure activity relationship of cyclotides in general, and the differences between subfamilies and the role of their hydrophobic surface in particular. Selective chemical modifications of Glu, Arg, Lys and Trp residues was tested for cytotoxic activity and derivatives in which the Trp residue was modified showed low effect, suggesting the existence of a connection between hydrophobicity and activity. However, over the full set of cyclotides examined, there was no strong correlation between the cytotoxic activity and their hydrophobicity. Instead, it seems more like that the distribution of charged and hydrophobic residues determines the ultimate degree of potency. Furthermore, we found that while the Glu residue is very important in maintaining the activity of the bracelet cyclotide cycloviolacin O2, it is much less important in the Möbius cyclotides. However, despite these differences, a systematic test of mixtures of cyclotides, even from both subfamilies revealed that they act in an additive way.

     

  • 16.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Larsson, Sonny
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Yeshak, Mariamawit
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Rosengren, Johan
    University of Queensland, Institute for Molecular Bioscience.
    Craik, David
    University of Queensland, Institute for Molecular Bioscience.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Distribution of cicular peptides in plants: Large scale mapping of cyclotides in the ViolaceaeManuscript (preprint) (Other academic)
    Abstract [en]

    During last decade there has been increased interest in the small, cysteine-rich cyclotide proteins found in plant species of the violet family (Violaceae). These cyclotides consist of a circular chain of approximately 30 amino acids, including six cysteines that form three disulfide bonds, arranged in a cyclic cystine knot motif. In this study we map the occurrence and distribution of cyclotides in the Violaceae. Plant material was obtained from herbarium sheets containing samples up to 200 years old. Even the oldest specimens exhibited a remarkable stability of cyclotides in the preserved leaves, with no degradation products observable, making them one of the most stable proteins in nature. We analyzed the cyclotide content in over 200 samples covering 17 of the 23 genera, and positively identified cyclotides in almost 150 of approximately 900 known species in the Violaceae. Each species contained a unique set of between one and 25 cyclotides, of which many were exclusive to individual species. The estimated number of different cyclotides in the Violaceae is 5,000-25,000. We conclude that the Violaceae is an extremely rich source of cyclotides, and we propose that cyclotides are ubiquitous among all Violaceae species.

  • 17.
    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.

  • 18.
    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.
    Membrane integrity as a target for cyclotide cytotoxic activityManuscript (preprint) (Other academic)
    Abstract [en]

    The cyclotides are a family of plant-derived proteins that occur in plants from the Violaceae (violet) and Rubiaceae (coffee) families and have a diverse range of biological activities, including cytotoxic, hemolytic, antimicrobial, and insecticidal activities; the latter suggests their natural function lies in plant defense. In the current study we have investigated the membrane-disrupting and adsorption ability of prototypic cyclotides and correlated these findings to their cytotoxic properties. We also included modifications of selected charged amino acids in cycloviolacin O2, previously shown to be of importance for its cytotoxic activity. The cyclotides’ cytotoxic activity, ability to adsorb and disrupt model lipid membranes of different charge densities was investigated, e.g. by fluorescence spectroscopy, ellipsometry, and circular dichroism. Cytotoxicity of the native cyclotides was demonstrated to correlate to membrane adsorption and lytic activity. Hence, the activity of native cyclotides is mainly due to interactions between the proteins and the phospholipids in the target membrane. Striking effects of single amino acid variations in cycloviolacin O2 on its membrane interaction were also demonstrated.

     

  • 19.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Svedlund, Erika
    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.
    Hassan, Saadia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Herrmann, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Clark, Richard J.
    University of Queensland, Institute for Molecular Bioscience.
    Craik, David J.
    University of Queensland, Institute for Molecular Bioscience.
    Bohlin, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Claeson, Per
    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.
    Gullbo, Joachim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Evaluation of toxicity and anti-tumour activity of cycloviolacin O2 in mice.2010In: Biopolymers, ISSN 0006-3525, E-ISSN 1097-0282, Vol. 94, no 5, p. 626-634Article in journal (Refereed)
    Abstract [en]

    Cycloviolacin O2 is a small cyclic cysteine-rich protein belonging to the group of plant proteins called cyclotides. This cyclotide has been previously shown to exert cytotoxic activity against a variety of human tumor cell lines as well as primary cultures of human tumor cells in vitro. This study is the first evaluation of its tolerability and antitumor activity in vivo. Maximal-tolerated doses were estimated to 1.5 mg/kg for single intravenous (i.v.) dosing and 0.5 mg/kg for daily repeated dosing, respectively. Two different in vivo methods were used: the hollow fiber method with single dosing (i.v. 1.0 mg/kg) and traditional xenografts with repeated dosing over 2 weeks (i.v. 0.5 mg/kg daily, 5 days a week). The human tumor cell lines used displayed dose-dependent in vitro sensitivity (including growth in hollow fibers to confirm passage of cycloviolacin O2 through the polyvinylidene fluoride fibers), with IC50 values in the micromolar range. Despite this sensitivity in vitro, no significant antitumor effects were detected in vivo, neither with single dosing in the hollow fiber method nor with repeated dosing in xenografts. In summary, the results indicate that antitumor effects are minor or absent at tolerable (sublethal) doses, and cycloviolacin O2 has a very abrupt in vivo toxicity profile, with lethality after single injection at 2 mg/kg, but no signs of discomfort to the animals at 1.5 mg/kg. Repeated dosing of 1 mg/kg gave a local-inflammatory reaction at the site of injection after 2–3 days; lower doses were without complications.

  • 20.
    Burman, Robert
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Yeshak, Mariamawit Y.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Univ Addis Ababa, Sch Pharm, Dept Pharmacognosy, Addis Ababa, Ethiopia..
    Larsson, Sonny
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Craik, David J.
    Univ Queensland, Inst Mol Biosci, Chem & Struct Biol Div, Craik Lab, Brisbane, Qld, Australia..
    Rosengren, K. Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Univ Queensland, Sch Biomed Sci, Lab Peptide Struct Biol, Brisbane, Qld, Australia..
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Distribution of circular proteins in plants: large-scale mapping of cyclotides in the Violaceae2015In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 6, article id 855Article in journal (Refereed)
    Abstract [en]

    During the last decade there has been increasing interest in small circular proteins found in plants of the violet family (Violaceae). These so-called cyclotides consist of a circular chain of approximately 30 amino acids, including six cysteines forming three disulfide bonds, arranged in a cyclic cystine knot (CCK) motif. In this study we map the occurrence and distribution of cyclotides throughout the Violaceae. Plant material was obtained from herbarium sheets containing samples up to 200 years of age. Even the oldest specimens contained cyclotides in the preserved leaves, with no degradation products observable, confirming their place as one of the most stable proteins in nature. Over 200 samples covering 17 of the 23-31 genera in Violaceae were analyzed, and cyclotides were positively identified in 150 species. Each species contained a unique set of between one and 25 cyclotides, with many exclusive to individual plant species. We estimate the number of different cyclotides in the Violaceae to be 5000-25,000, and propose that cyclotides are ubiquitous among all Violaceae species. Twelve new cyclotides from six phylogenetically dispersed genera were sequenced. Furthermore, the first glycosylated derivatives of cyclotides were identified and characterized, further increasing the diversity and complexity of this unique protein family.

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  • 21.
    Carstens, Bodil B.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy. Univ Queensland, Inst Mol Biosci, Brisbane, Qld 4072, Australia..
    Rosengren, K. Johan
    Univ Queensland, Sch Biomed Sci, Brisbane, Qld 4072, Australia..
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Schempp, Stefanie
    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.
    Dahlstrom, Mia
    SP Tech Res Inst Sweden, Dept Chem Mat & Surfaces, SE-41346 Gothenburg, Sweden..
    Clark, Richard J.
    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, Division of Pharmacognosy.
    Isolation, Characterization, and Synthesis of the Barrettides: Disulfide-Containing Peptides from the Marine Sponge Geodia barretti2015In: Journal of natural products (Print), ISSN 0163-3864, E-ISSN 1520-6025, Vol. 78, no 8, p. 1886-1893Article in journal (Refereed)
    Abstract [en]

    Two disulfide-containing peptides, barrettides A (1) and B (2), from the cold-water marine sponge Geodia barretti are described. Those 31 amino acid residue long peptides were sequenced using mass spectrometry methods and structurally characterized using NMR spectroscopy. The structure of 1 was confirmed by total synthesis using the solid-phase peptide synthesis approach that was developed. The two peptides were found to differ only at a single position in their sequence. The three-dimensional structure of 1 revealed that these peptides possess a unique fold consisting of a long beta-hairpin structure that is cross-braced by two disulfide bonds in a ladder-like arrangement. The peptides are amphipathic in nature with the hydrophobic and charged residues clustered on separate faces of the molecule. The barrettides were found not to inhibit the growth of either Escherichia coli or Staphylococcus aureus but displayed antifouling activity against barnacle larvae (Balanus improvisus) without lethal effects in the concentrations tested.

  • 22.
    Claeson, Per
    et al.