(+)-pinoresinol-O--D-glucopyranoside from Eucommia ulmoides Oliver and its anti-inflammatory and antiviral effects against influenza A (H1N1) virus infection

Eucommia ulmoides Oliver (Du-Zhong) is an ancient Chinese herbal remedy used for the treatment of various diseases. To date, the effects of its constituent lignans on influenza viruses remain to be elucidated. In the present study, a lignan glycoside was isolated and purified from Eucommia ulmoides Oliver. Its structures were identified via extensive spectroscopic analysis, and its antiviral and anti-inflammatory activities, specifically against influenza viruses, were determined via a cytopathic effect (CPE) assay, plaque-reduction assays, a progeny virus yield reduction assay, reverse transcription-quantitative polymerase chain reaction analysis and a Luminex assay. Additionally, western blot analysis was performed to investigate the underlying mechanisms of its effects against influenza viruses. The chemical and spectroscopic methods determined the structure of lignan glycoside to be (+)-pinoresinol-O--D-glucopyranoside. The CPE assay showed that (+)-pinoresinol-O--D-glucopyranoside exerted inhibitory activities with 50% inhibition concentration values of 408.81 +/- 5.24 and 176.24 +/- 4.41 mu g/ml against the influenza A/PR/8/34 (H1N1) and A/Guangzhou/GIRD07/09 (H1N1) strains, respectively. Its antiviral properties were confirmed by plaque reduction and progeny virus yield reduction assays. Additional mechanistic analyses indicated that the anti-H1N1 virus-induced effects of (+)-pinoresinol-O--D-glucopyranoside were likely due to inactivation of the nuclear factor-B, p38 mitogen-activated protein kinase and AKT signaling pathways. Furthermore, (+)-pinoresinol-O--D-glucopyranoside exhibited pronounced inhibitory effects on the expression of influenza H1N1 virus-induced pro-inflammatory mediators, including tumor necrosis factor-, interleukin (IL)-6, IL-8 and monocyte chemoattractant protein 1. The data obtained suggest that (+)-pinoresinol-O--D-glucopyranoside may be a candidate drug for treating influenza H1N1 virus infection.