Fig. 5.

Haemolysis-inhibiting activity of compound 10a against influenza A virus HA. The compound was mixed with 128 hemagglutinating units of influenza virus, incubated at room temperature for 30 min, mixed with 0.75% chicken erythrocytes, and incubated at +4°C. After incubation with MES buffer (0.1 M MES, 0.15 M NaCl, 0.9 mM CaCl₂, 0.5 mM MgCl₂, pH 5.0) and sedimentation of erythrocytes, the optical density in the wells was measured at 405 nm. The haemolysis-inhibiting activity of compound 10a was calculated by comparison to the haemolysis activity of influenza A virus without additives.