Ent‐atisane Diterpenoids with Anti‐influenza Virus Activity from Mangrove Plant Excoecaria agallocha L.

Three new ent-atisane diterpenoids, named agallolides N‒P (1-3) together with nine known diterpenoids (4-12) were isolated from the stems and twigs of the mangrove plant, Excoecaria agallocha L.. Various techniques, including HR-ESIMS, spectroscopic methods, 13C-NMR calculations and DP4+probability analysis, and ECD calculations were applied to determine their molecular structures. The anti-influenza virus activities of 1-12 against A/PR/8/34 (H1N1), ZX1109 (H1N1, oseltamivir resistant virus), HK68 (H3N2), and B/Florida/78/2015 were evaluated. Compounds 8 and 12 showed significant antiviral activities against those four virus strains with EC50 values ranging from 0.54 to 19.53 μM. Moreover, compound 8 exhibited notable antiviral activity against A/PR/8/34, ZX1109, and B/Florida/78/2015 with EC50 value of 2.82, 3.45, and 0.54 μM, respectively, which were more potent than the positive control oseltamivir. This findings suggest that compound 8 may be a potential structure basis for developing anti-influenza agents.