Publications by Cyril Portmann

Balgacyclamides, Antiplasmodial Heterocyclic Peptides from Microcystis aeruguinosa EAWAG 251

Karl Gademann, Laeticia Da Silva, Simon Sieber, Cyril Portmann, Emilie Baudat

The isolation and structural characterization of three new heterocyclic and macrocyclic peptides, balgacyclamides A C, from Microcystis aeruginosa EAWAG 251 are reported. The constitutions were determined by 2D-NMR methods and mass spectrometry, and the co ...

Amer Chemical Soc2014

Telomerase Inhibitors from Cyanobacteria: Isolation and Synthesis of Sulfoquinovosyl Diacylglycerols from

Gerardo Turcatti, Damiano Banfi, Karl Gademann, Joachim Lingner, Laeticia Da Silva, Cyril Portmann, Emilie Baudat, Tom Woods

By using the Telospot assay, 27 different extracts of cyanobacteria were evaluated for telomerase inhibition. All extracts showed varying, but significant activity. We selected Microcystis aeruguinosa PCC 7806 to identify the active compound and a bioassay ...

Wiley-Blackwell2013

Multiple Toxin Production in the Cyanobacterium Microcystis: Isolation of the Toxic Protease Inhibitor Cyanopeptolin 1020

Karl Gademann, Cyril Portmann

The isolation and structure of cyanopeptolin 1020 (hexanoic acid-Glu-N[-O-Thr-Arg-Ahp-Phe-N-Me-Tyr-Val-]) from a Microcystis strain is reported. Very potent picomolar trypsin inhibition (IC50 = 670 pM) and low nanomolar values against human kallikrein (4.5 ...

2010

Surface Assembly of Catechol-Functionalized Poly(l-lysine)-graft-poly(ethylene glycol) Copolymer on Titanium Exploiting Combined Electrostatically Driven Self-Organization and Biomimetic Strong Adhesion

Karl Gademann, Cyril Portmann

Nonfouling coatings, based on surface-tethered, hydrophilic polymer chains, have widespread application in areas such as biosensing, medical devices, and biotechnology. Self-organization of polymers is a particularly attractive approach given its simplicit ...

American Chemical Society2010

Spatial isolation favours the divergence in microcystin net production by Microcystis in Ugandan freshwater lakes

Karl Gademann, Cyril Portmann

It is generally agreed that the hepatotoxic microcystins (MCs) are the most abundant toxins produced by cyanobacteria in freshwater. In various freshwater lakes in East Africa MC-producing Microcystis has been reported to dominate the phytoplankton, howeve ...

2010

Biologically active secondary metabolites from cyanobacteria

Cyril Portmann

For millennia, nature was the only source of medicine for mankind. Even today natural products represent a large proportion of the drugs in use. In some areas, like cancer or infectious diseases, about 50 % of the compounds used are of natural origin. Cyan ...

EPFL2010

Occurrence of microcystin-producing cyanobacteria in Ugandan freshwater habitats

Karl Gademann, Cyril Portmann

Microcystins (MCs) are cyclic heptapeptides, which are the most abundant toxins produced by cyanobacteria in freshwater. The phytoplankton of many freshwater lakes in Eastern Africa is dominated by cyanobacteria. Less is known, however, on the occurrence o ...

2010

New antiplasmodial natural products from cyanobacteria: linking their ecological role to their therapeutic potential

Karl Gademann, Cyril Portmann

Cyanobacteria (blue-green algae) produce many metabolites that are directed towards competing photoautotrophs. Such algicidal compounds might offer new approaches for the selective inhibition of the malaria parasite, Plasmodium falciparum, as this organism ...

2009

Directed Biosynthesis of Phytotoxic Alkaloids in the Cyanobacterium Nostoc 78-12A

Karl Gademann, Cora Prestinari, Cyril Portmann, Theresa Myers

Nostocarboline, a chlorinated and N-methylated carbolinium alkaloid, displays potent and selective inhibition of photoautotrophic organisms as well as the malaria parasite Plasmodium falciparum, while showing very low toxicity to bacterial and fungal patho ...

2009

Aerucyclamides A and B: Isolation and Synthesis of Toxic Ribosomal Heterocyclic Peptides from the Cyanobacterium Microcystis aeruginosa PCC 7806

Karl Gademann, Cyril Portmann

Two new modified hexacyclopeptides, aerucyclamides A and B, were isolated from the toxic freshwater cyanobacterium Microcystis aeruginosa PCC 7806. The constitution was assigned by spectroscopic methods, and the configuration determined by chemical degrada ...

2008

Isolation of Aerucyclamides C and D and Structure Revision of Microcyclamide 7806A: Heterocyclic Ribosomal Peptides from Microcystis aeruginosa PCC 7806 and Their Antiparasite Evaluation

Karl Gademann, Cyril Portmann

Aerucyclamides C and D were isolated from the cyanobacterium Microcystis aeruginosa PCC 7806, and their structures established by NMR spectroscopy and chemical transformation and degradation. Acidic hydrolysis of aerucyclamide C (CF3CO2H, H2O) resulted in ...

2008

Secondary Metabolites from Cyanobacteria: Complex Structures and Powerful Bioactivities

Karl Gademann, Cyril Portmann

This review presents natural products from cyanobacteria. Several classes of secondary metabolites are highlighted. Toxic metabolites from these prokaryotic photosynthetic organisms include compounds such as microcystin, anatoxin and saxitoxin, which displ ...

2008

Isolation and Structure Determination of Two Microcystins and Sequence Comparison of the McyABC Adenylation Domains in Planktothrix Species

Karl Gademann, Cyril Portmann

Microcystins (MCs) are toxic heptapeptides found in cyanobacteria and share the common structure cyclo(-D-Ala1-L- X2-D-isoMeAsp3-L-Z4-Adda5-D-isoGlu6-Mdha7). The letters X and Z in the general formula above represent a wide range of L-amino acids that occu ...

2008