Roles of the antioxidant properties of icariin and its phosphorylated derivative in the protection against duck virus hepatitis

BACKGROUND Duck viral hepatitis (DVH) is an acute disease of young ducklings with few convenient and effective veterinary drugs to treat. In pathology, present study mainly focused on the immune mechanism, but very few studies have concerned with the role of oxidative stress in the pathogenesis of DVH. To study the antioxidative and hepatoprotective effects of icariin and its phosphorylated derivative against DVH, we prepared phosphorylated icariin (p-icariin) using the sodium trimetaphosphate-sodium tripolyphosphate method. Ducklings were drunk with icariin and p-icariin after being challenged with duck hepatitis virus 1 (DHV-1). We recorded the number of dead ducklings, gross pathological changes in the liver, and changes in indices of oxidative stress and liver injury. The correlations between these indices were also analyzed. RESULTS Exposure to DHV-1 induced significant oxidative damage in ducklings. Administration of icariin or p-icariin attenuated liver pathological injury and significantly increased the survival rate, with better outcomes in ducklings treated with p-icariin than in those treated with icariin. Icariin and p-icariin also attenuated the changes in oxidative stress and liver injury. We found positive correlations among indices of oxidative stress (malondialdehyde and inducible nitric oxide synthase) and liver injury (alanine aminotransferase, alkaline phosphatase, and lactate dehydrogenase), suggesting that DHV-1 causes significant oxidative damage, which is related to the extent of hepatic injury. CONCLUSIONS Icariin and p-icariin improved the survival and attenuated oxidative stress and liver dysfunction induced by DHV-1. These outcomes were better in ducklings treated with p-icariin than in those treated by icariin. The clinical effects of both components were related to their antioxidant activities.