title: Antiviral effect of emodin from Rheum palmatum against coxsakievirus B5 and human respiratory syncytial virus in vitro.
abstract: Viral infections are the major causes of morbidity and mortality in elderly people and young children throughout the world. The most common pathogens include coxsackie virus (CV) and respiratory syncytial virus (RSV). However, no antiviral agents with low toxicity and drug resistance are currently available in clinic therapy. The present study aimed to examine the antiviral activities of emodin (an ingredient of Rheum palmatum) against CVB5 and RSV infections, in an attempt to discover new antiviral agents for virus infection. The monomer emodin was extracted and isolated from Rheum palmatum. The antiviral activities of emodin on HEp-2 cells were evaluated, including virus replication inhibition, virucidal and anti-absorption effects, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tet-razolium bromide (MTT) assay and plaque reduction assay (PRA). The kinetics of virus inhibition by emodin in a period of 14 h was further determined by plaque assay and quantitative real time PCR (qPCR). Cytokine (IFN-γ, TNF-α) mRNA expressions after emodin treatment (7.5, 15, 30 μmol/L) were also assessed by qPCR post-infection. The results showed that emodin had potent inhibitory activities against CVB5 and RSV, with the 50% effective concentration (EC50) ranging from 13.06 to 14.27 μmol/L and selectivity index (SI) being 5.38-6.41 μmol/L. However, emodin couldn't directly inactivate the viruses or block their absorption to cells. It acted as a biological synthesis inhibitor against CVB4 and RSV in a concentration- and time-dependent manner, especially during the first 0-4 h post-infection. Moreover, emodin could decrease the mRNA expression of IFN-α but enhance TNF-γ expression significantly compared to the viral controls in vitro. Our results provide a molecular basis for development of emodin as a novel and safe antiviral agent for human enterovirus and respiratory virus infection in the clinical therapy.
authors.affiliation: South-Central University for Nationalities, Wuhan, 430074, China. 3035407@mail.scuec.edu.cn.|State Key Laboratory of Virology, Institute of Medical Virology, School of Medicine, Wuhan University, Wuhan, 430071, China. 3035407@mail.scuec.edu.cn.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Virology, Institute of Medical Virology, School of Medicine, Wuhan University, Wuhan, 430071, China.
authors.forename: Nian
authors.initials: N
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Virology, Institute of Medical Virology, School of Medicine, Wuhan University, Wuhan, 430071, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: State Key Laboratory of Virology, Institute of Medical Virology, School of Medicine, Wuhan University, Wuhan, 430071, China.
authors.forename: Zhan-Qiu
authors.initials: ZQ
authors.lastname: Yang
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D045744:Cell Line, Tumor; D004642:Emodin / Q000494:pharmacology*; D029822:Enterovirus B, Human / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D012136:Respiratory Syncytial Viruses / Q000187:drug effects* / Q000502:physiology; D012250:Rheum / Q000737:chemistry*; D014779:Virus Replication
chemical_list: D000998:Antiviral Agents; D004642:Emodin
keywords: antiviral effect; coxsakievirus B5; emodin; respiratory syncytial virus