Inhibitory Effects of Cryptotanshinone and Dihydrotanshinone I on Intracellular Trafficking of Viral Glycoproteins

Antiviral agents that target the viral envelope surface glycoproteins can disrupt the interactions between the viral glycoproteins and host cell receptors, thereby preventing viral entry into host cells. However, the mechanisms underlying glycoprotein processing and cellular trafficking have not been fully elucidated. In this study, we aimed to investigate the mechanism of action of cryptotanshinone (CTN) and dihydrotanshinone I (DTN) as inhibitors of viral glycoprotein trafficking, by assessing their inhibitory action on syncytium formation and cytopathic effects. CTN and DTN were isolated and characterized from <i>Salvia miltiorrhiza</i>; they effectively inhibited syncytium formation in Newcastle disease virus-infected baby hamster kidney cells. Both compounds inhibited the transport of viral G-proteins to the cell surface, resulting in intracellular accumulation. These results suggest that CTN and DTN are potential glycoprotein trafficking inhibitors that function at the Golgi apparatus. Overall, our results indicate that CTN and DTN suppress intracellular glycosylation by competing as inhibitors of glycosylation trafficking.