Determine the structure of phosphorylated modification of icariin and its antiviral activity against duck hepatitis virus A

Background: Our previous research showed that icariin (1) and its phosphorylated structural modification (2) improved the survival and attenuated oxidative stress and liver dysfunction induced by duck virus hepatitis. In this paper, we were one step closer to determine the structure of phosphorylation icariin (2) by the FT-IR, HRESIMS and C-13 NMR. Anti-DHAV activities of 1 and 2 were compared in duck embryonic hepatocytes (DEHs) cultured in vitro and by artificial infection method in vivo. Additionally, the antiviral mechanisms of replication/release in vitro and the DHAV gene expression in vivo of 1 and 2 were analyzed. Results: Compound 2's molecular formula was C33H42O18P. The results indicated that 1 and 2 effectively resisted DHAV invading DEHs, that they decreased the mortality of ducklings challenged with DHAV, and that 2 performed more effectively. 1 and 2 performed evenly on DHAV release; however, 2 restrained virus replication far more effectively. Since the anti-DHAV mechanisms of 1 and 2 in vitro probably involve suppression of replication and release, 2's better performance in anti-DHAV may result from its far more effectively inhibiting virus replication. Conclusions: The compound 2's chemical structure was defined as 8-prenylkaempferol-4'-methylether-3-rhamnosyl-7( 6'''-phosphate)-glycoside. 1 and 2 exhibited anti-virus activity on DHAV. Our results suggest that 1 and 2 might become an anti-virus plant material candidate.