Ephedra sinica Stapf, known as a medicinal plant, inhibited not only syncytium formation, but also trafficking of viral glycoprotein, hemagglutinin-neuramidase (HN) to the cell-surface. Trafficking of viral glycoprotein to the surface of infected-cells results in syncytium formation in Newcastle disease virus (NDV)-infected baby hamster kidney (BHK) cells. Viral glycoprotein in the infected-cell is processed within the endoplasmic reticulum during routing into surface. The processing of viral glycoprotein like a N-linked oligosaccharide trimming by α-glucosidase in cell is necessary for virus infection. Methanol extracts showed inhibitory activities (IC50 15 μg/mL) against α -glucosidase. This suggested that E. sinica extracts inhibited the cell-surface expression of NDV-HN glycoprotein without significantly affecting HN glycoprotein synthesis in NDV-infected BHK cells.

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