Pite these differences in their anti-H5N1 mechanisms, each compounds enhanced H5N1-induced ROS formationin A549 cells, and the efficacy of each compounds was enhanced by the antioxidant NAC. In contrast, inhibition of flavonoid-induced ROS formation by NAC didn’t have an effect on virus replication in H5N1-infected macrophages. These findings emphasise that flavonoids, a class of organic compounds known to exert anti-influenza effects [16-19,28], induce a complex range of pharmacological actions by which they modify influenza A virus replication which includes hugely pathogenic avian H5N1 strains. These actions may be cell type-specific and incorporate pro- and antiviral effects. The all round activity might be the result in the totality of effects exerted by a specific flavonoid within a particular cell kind. A more detailed understanding of those actions plus the underlying structure-activity relationships is needed so as to style structures with optimised anti-influenza activity.AROS positive cells ( ) one hundred 80 60 400 H5N1 biochanin A baicalein NAC-+ -+ + -+ + -+ ++ + ++ + +B12000 10000 8000 6000 4000 2000 0 H5N1 biochanin A baicalein NAC TCID50/mL-+ -+ + -+ + -+ ++ + ++ + +Figure three Effects of baicalein and biochanin A on reactive oxygen species (ROS) formation and H5N1 replication in key human monocyte-derived macrophages in combination with N-acetyl-L-cysteine (NAC). Macrophages were infected with H5N1 strain A/Thailand/1 (Kan-1)/04 (MOI 1). Drugs were constantly present beginning using a 1 h pre-incubation period. Virus titres had been determined 48 h post infection. A) Effects of flavonoids 40 M and/or NAC 5 mM on H5N1-induced ROS formation, `-‘ indicates absence of virus or respective compound, `+’ indicates presence of virus or respective compound. *P 0.05 relative to flavonoids alone; B) Effects of baicalein 40 M or biochanin A 40 M within the presence or absence of NAC 5 mM on H5N1 titres. `-‘ indicates absence of virus or respective compound, `+’ indicates presence of virus or respective compound. Values are presented as mean S.D. from three distinct independent experiments.Michaelis et al. BMC Investigation Notes 2014, 7:384 http://www.biomedcentral/1756-0500/7/Page 5 ofAbbreviations NAC: N-acetyl-L-cysteine; ROS: Reactive oxygen species. Competing interests The authors declare that they have no competing interests. Authors’ contributions MM and JC developed the study, analysed the information, and wrote the manuscript. PS performed experiments and analysed data.Glofitamab All authors read and authorized the final manuscript.Gentamicin sulfate Acknowledgements The authors thank Mrs. Christina Matreux, Mrs. Kerstin Euler, Mrs. Gesa Meincke, and Mrs. Rosy Schmidt for technical supports.PMID:23865629 This function was supported by the EU (SARS/FLU vaccine/ proposal no. 512054, Chimeric Vaccines/ proposal no. 512864, Intranasal H5 vaccine, proposal no. 044512), by the Hilfe f krebskranke Kinder Frankfurt e.V., and by the Frankfurter Stiftung f krebskranke Kinder. P. Sithisarn was supported by a FRA scholarship in the Royal Thai Government. Author particulars 1 Institute for Healthcare Virology, Clinics on the Goethe-University, Paul Ehrlich-Str. 40, 60596 Frankfurt am Most important, Germany. 2Current address: Centre for Molecular Processing and School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK. 3Current address: Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand. Received: 24 April 2014 Accepted: 13 June 2014 Published: 23 June 2014 References 1. Cheung CL, Rayner JM, Smith GJ, Wang P, N.