XK and influenza: Chukicheva et al. [91] performed a preliminary evaluation of the antiviral activity of terpenophenols and their N or O-containing derivatives, in which 2-(1,7,7-Trimethylbicyclo [2.2.1]hept-exo-2-yl)cyclohexa-2,5-dien-1,4-dione (85) (Figure 10) was the most active influenza NA inhibitor, with an IC50 = 0.5 μM (Table 1).