Secoiridoid analogues from the fruits of Ligustrum lucidum and their inhibitory activities against influenza A virus.

A phytochemical study focusing on the secoiridoid components in the fruits of Ligustrum lucidum was carried out, which finally led to the isolation of nine secoiridoid glycosides (1-9) together with two secoiridoids (10, 11). The structures of all compounds were established mainly by NMR and MS experiments as well as the necessary chemical evidence, of which 1, 2, 4 (ligulucisides A-C), 10 and 11 (liguluciridoids A and B) were identified as new secoiridoid analogues. An in vitro antiviral bioassay indicated that 1, 4, 6, and 10 displayed the inhibitory activities against influenza A virus with the IC50 values of 16.5, 12.5, 13.1, and 18.5 μM, respectively, which were better than the positive control Ribavirin (IC50 22.6 μM). .