In vitro antiviral activity of phlorotannins isolated from Ecklonia cava against porcine epidemic diarrhea coronavirus infection and hemagglutination

Abstract

Despite the prepdominat agent causing severe entero-pathogenic diarrhea in swine, there are no effective therapeutical treatment of porcine epidemic diarrhea virus (PEDV). In this study, we evaluated the antiviral activity of five phlorotannins isolated from Ecklonia cava (E. cava) against PEDV. In vitro antiviral activity was tested using two different assay strategies: (1) blockage of the binding of virus to cells (simultaneous-treatment assay) and (2) inhibition of viral replication (post-treatment assay). In simultaneous-treatment assay, compounds 2-5 except compound 1 exhibited antiviral activities of a 50% inhibitory concentration (IC₅₀) with the ranging from 10.8 ± 1.4 to 22.5 ± 2.2 μM against PEDV. Compounds 1-5 were completely blocked binding of viral spike protein to sialic acids at less than 36.6 μM concentrations by hemagglutination inhibition. Moreover, compounds 4 and 5 of five phlorotannins inhibited viral replication with IC₅₀ values of 12.2 ± 2.8 and 14.6 ± 1.3 μM in the post-treatment assay, respectively. During virus replication steps, compounds 4 and 5 exhibited stronger inhibition of viral RNA and viral protein synthesis in late stages (18 and 24 h) than in early stages (6 and 12 h). Interestingly, compounds 4 and 5 inhibited both viral entry by hemagglutination inhibition and viral replication by inhibition of viral RNA and viral protein synthesis, but not viral protease. These results suggest that compounds isolated from E. cava have strong antiviral activity against PEDV, inhibiting viral entry and/or viral replication, and may be developed into natural therapeutic drugs against coronavirus infection.

Antiviral effect of lithium chloride on porcine epidemic diarrhea virus in vitro

“…Vaccination is a fundamental strategy for controlling and eradicating PED during epidemic or endemic outbreaks, but the efficacy is limited (Baek et al, 2016;Shen et al, 2015). Until now there is no recorded clinically effective antiviral chemotherapeutic agent for treatment of disease caused by PEDV, even several compounds were demonstrated having antiviral activity in PEDV-infected Vero cells (Deejai et al, 2017;Yang et al, 2015;Lee et al, 2015;Kwon et al, 2013;Choi et al, 2009). So it is important to develop an effective strategy against PEDV infection.…”

Phlorotannins

“…In another study, dieckol showed adipogenesis inhibition and down-regulated the expression of PPARg, CCAAT/enhancer-binding proteins (C/EBP a ), sterol regulatory element-binding protein 1 (SREBP1) and fatty acid binding protein 4 (FABP4) in a dose-dependent manner. The specific mechanism mediating the effects of dieckol was confirmed by AMP-activated protein kinase (AMPK) activation (Ko et al, 2013).…”

In vitro anti-reovirus activity of kuraridin isolated from Sophora flavescens against viral replication and hemagglutination

“…The antiviral assays have been previously described (24), and the visualization of these assays was performed by neutral red method as briefly described.…”