Unraveling the anti-influenza potential of polypores
Due to the increase of viral resistance and a constant threat of pandemics, the current portfolio of anti-influenza drugs needs extension. In this context, locally grown European polypores belonging to the class of Agaricomycetes were investigated as source for anti-influenza agents from nature. Fruit bodies of several strains from ten species including Fomes fomentarius, Fomitopsis pinicola, Ganoderma lucidum, G. applanatum, Gloeophyllum odoratum, Ischnoderma benzoinum, Laetiporus sulphureus, Phellinus robustus, Piptoporus betulinus, and Trametes gibbosa were collected and unambiguously identified via rDNA ITS phylogenetic analyses. In MDCK cells, the generated ethanol extracts were screened in a cytopathic effect (CPE) inhibition assay using the H3N2 influenza virus A/Hong Kong/68 (HK/68). In particular, the extract of a G. odoratum strain dose-dependently inhibited the CPE with an IC50 of 19.5 µg/mL. Results from the fluorescence-based neuraminidase inhibition assay ruled out that the antiviral activity was based on the inhibition of the surface protein neuraminidase. In several chromatographic steps, eight lanostane triterpenes were isolated and identified via HRESIMS, and 1D and 2D NMR spectroscopy. Among them were two novel constituents as well as three compounds so far undescribed for this species. The most potent activity was determined for trametenolic acid B against H3N2 strain HK/68 and the 2009 pandemic H1N1 strain A/Jena/8178/09 with IC50s of 14.1 and 11.3 µM, respectively. In a plaque reduction assay, this compound was able to bind to cell-free viruses and to neutralize their infectivity.
Supported by the Austrian Science Fund (FWF: P24587) and the European Social Fund (ESF & TMWAT Project 2011 FGR 0137).
Zwirchmayr Julia1 Grienke Ulrike1 Richter Martina2 Mair E. Christina1 Peintner Ursula3 Schmidtke Michaela2 Rollinger M. Judith1
Department of Pharmacognosy, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria, Austria
Institute of Medical Microbiology, Section Experimental Virology, Jena University Hospital, Hans-Knöll-Straße 2, 07745 Jena, Germany, Germany
Institute of Microbiology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria, Austria