Structural modification on rupestonic acid leads to highly potent inhibitors against influenza virus.

Influenza viruses are responsible for seasonal epidemics and occasional pandemics, which cause significant morbidity and mortality. Although several drugs (adamantanes and neuraminidase inhibitors) are available in the market, the worldwide spread of drug-resistant influenza strains poses an urgent need for novel antiviral drugs. Artemisia rupestris L. is a folk medicine used to treat cold. In this paper, we structurally modified rupestonic acid, a bioactive component of A. rupestris, to synthesize a series of 2-substituted rupestonic acid methyl esters (3a-3o). Their structures were fully characterized by 1 H NMR, 13 C NMR, HRMS spectra. Among them, compounds 3b and 3c exhibited potent activities against influenza H1N1 with micromolar IC50 values and might serve as new lead compounds for the treatment of influenza.