Endonuclease inhibition (FRET), anti-viral effect (CPE), cytotoxic dose and thermo-stabilisation (Tm) of pH1N1 PA-Nter by diketo compounds and EGCG.

aFluorescence resonance energy transfer (FRET) based endonuclease activity assay. FRET measurements were determined in quadruplicates with at least two independent sets. Mean values and 95% confidence limits (as indicated) were calculated. bReduction of virus induced cytopathic effect (CPE); inactive: no antiviral activity at the highest concentration tested. For CPE IC50 and CC50 values samples were applied in duplicates and IC50 values, CC50 values, and corresponding 95% confidence intervals were determined. The experiments were independently performed at least twice. c48 h cytotoxicity on MDCK cells. dNo cytotoxicity at the highest concentration tested (mainly limited by solubility). eApparent melting temperature Tm derived from Thermofluor measurements. fNot determined due to fluorescence quenching.