title: Antipneumococcal activity of neuraminidase inhibiting artocarpin.
abstract: Streptococcus (S.) pneumoniae is a major cause of secondary bacterial pneumonia during influenza epidemics. Neuraminidase (NA) is a virulence factor of both pneumococci and influenza viruses. Bacterial neuraminidases (NAs) are structurally related to viral NA and susceptible to oseltamivir, an inhibitor designed to target viral NA. This prompted us to evaluate the antipneumococcal potential of two NA inhibiting natural compounds, the diarylheptanoid katsumadain A and the isoprenylated flavone artocarpin. Chemiluminescence, fluorescence-, and hemagglutination-based enzyme assays were applied to determine the inhibitory efficiency (IC(50) value) of the tested compounds towards pneumococcal NAs. The mechanism of inhibition was studied via enzyme kinetics with recombinant NanA NA. Unlike oseltamivir, which competes with the natural substrate of NA, artocarpin exhibits a mixed-type inhibition with a Ki value of 9.70 μM. Remarkably, artocarpin was the only NA inhibitor (NAI) for which an inhibitory effect on pneumococcal growth (MIC: 0.99-5.75 μM) and biofilm formation (MBIC: 1.15-2.97 μM) was observable. In addition, we discovered that the bactericidal effect of artocarpin can reduce the viability of pneumococci by a factor of >1000, without obvious harm to lung epithelial cells. This renders artocarpin a promising natural product for further investigations.
authors.affiliation: Jena University Hospital, Department of Virology and Antiviral Therapy, Hans-Knöll-Straße 2, 07745 Jena, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Walther
authors.affiliation: Jena University Hospital, Department of Virology and Antiviral Therapy, Hans-Knöll-Straße 2, 07745 Jena, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Richter
authors.affiliation: Jena University Hospital, Department of Virology and Antiviral Therapy, Hans-Knöll-Straße 2, 07745 Jena, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Xu
authors.affiliation: University of Innsbruck, Institute for General, Inorganic and Theoretical Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Kramer
authors.affiliation: University of Innsbruck, Institute for General, Inorganic and Theoretical Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: S
authors.initials: S
authors.lastname: von Grafenstein
authors.affiliation: University of Hamburg, Center for Bioinformatics, Bundesstraße 43, 20146 Hamburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kirchmair
authors.affiliation: University of Innsbruck, Institute of Pharmacy/Pharmacognosy and Center for Molecular Biosciences Innsbruck (CMBI), Innrain 80/82, 6020 Innsbruck, Austria; University of Vienna, Department of Pharmacognosy, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: U
authors.initials: U
authors.lastname: Grienke
authors.affiliation: University of Vienna, Department of Pharmacognosy, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: J M
authors.initials: JM
authors.lastname: Rollinger
authors.affiliation: University of Innsbruck, Institute for General, Inorganic and Theoretical Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: K R
authors.initials: KR
authors.lastname: Liedl
authors.affiliation: Jena University Hospital, ZIK Septomics, Albert-Einstein-Straße 10, 07745 Jena, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Slevogt
authors.affiliation: Jena University Hospital, Department of Virology and Antiviral Therapy, Hans-Knöll-Straße 2, 07745 Jena, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Sauerbrei
authors.affiliation: Leibniz Institute for Natural Product Research and Infection Biology, Beutenbergstraße 11a, 07745 Jena, Germany.
authors.forename: H P
authors.initials: HP
authors.lastname: Saluz
authors.affiliation: Jena University Hospital, Department of Medical Microbiology, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Pfister
authors.affiliation: Jena University Hospital, Department of Virology and Antiviral Therapy, Hans-Knöll-Straße 2, 07745 Jena, Germany. Electronic address: michaela.schmidtke@med.uni-jena.de.
authors.forename: M
authors.initials: M
authors.lastname: Schmidtke
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D036381:Diarylheptanoids / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D037241:Mannose-Binding Lectins / Q000494:pharmacology* / Q000633:toxicity; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D037121:Plant Lectins / Q000494:pharmacology* / Q000633:toxicity; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D036381:Diarylheptanoids; D004791:Enzyme Inhibitors; D037241:Mannose-Binding Lectins; D037121:Plant Lectins; C090683:artocarpin lectin; C404385:katsumadain A; D009439:Neuraminidase
keywords: Antipneumococcal; Artocarpin; Biofilm; DANA; Katsumadain A; NanA; Neuraminidase; Neuraminidase inhibitors; Oseltamivir; Pneumococci; Zanamivir