title: Anti-influenza virus effects of crude phenylethanoid glycosides isolated from ligustrum purpurascens via inducing endogenous interferon-γ.
abstract: BACKGROUND
  Ligustrum purpurascens Y.C. Yang (Oleaceae) is traditionally recorded as "Ku Ding Cha", a kind of functional tea in southern China for about two thousand years, which has been reported with sore throat alleviating and pathogenic heat expelling effects. However, there are no scientific studies demonstrating its antiviral activity.
  
  
  OBJECTIVE
  This study is aimed at investigating the anti-influenza virus effects of phenylethanoid glycosides isolated from L. purpurascens (LPG) as well as its corresponding mechanisms.
  
  
  METHODS
  In vitro, hemagglutination assay was employed to detect the influenza virus titer; In vivo, C57BL/6J mice were given oral administration of LPG (100mg/kg, 300mg/kg, 900mg/kg) or ribavirin (100mg/kg) once daily for 5 successive days. Meanwhile, on the second day, mice were infected intranasally (i.n.) with A/FM/1/47 H1N1 virus. Mice survival rate and other clinical index were monitored for 15 days. Infected mice were sacrificed to measure the lung lesion and stained with hematoxylin-eosin. Flow cytometry analyses spleen lymphocytes and interferon-γ (IFN-γ) level. The IFN-γ knockout mice (IFN-γ(-/-) mice, C57BL/6J) which had been verified lacking IFN-γ through Western Blot, were applied in the death-protection test to identify the role of IFN-γ played in LPG antiviral effect.
  
  
  RESULTS
  In vitro, LPG at 0.5mg/ml inhibited Influenza A Virus H1N1 type (H1N1) infection of MDCK cells. In vivo, LPG at 300 and 900mg/kg significantly decreased the mouse lung index (p<0.05), alleviated influenza-induced lethality and clinical symptoms, and therefore enhanced mouse survival (p<0.05). More detailed experiments demonstrated that antiviral cytokine IFN-γ was involved in the antiviral effect of LPG. Flow cytometric analysis revealed that LPG (900mg/kg) significantly induced secretion of IFN-γ by splenic CD4(+) and CD8(+) cells (p<0.05). Moreover, LPG (900mg/kg) protected wild-type C57BL/6J mice from H1N1 injury, whereas LPG-mediated survival protection disappeared in IFN-γ(-/-) mice.
  
  
  CONCLUSIONS
  These results suggest that up-regulating endogenous IFN-γ by LPG may represent a novel therapeutic approach for H1N1 infection.
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Xiao-peng
authors.initials: XP
authors.lastname: Hu
authors.affiliation: Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510405, China.
authors.forename: Min-ming
authors.initials: MM
authors.lastname: Shao
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China; School of Chinese Medicine, Hong Kong Baptist University, Hong Kong 999077, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Song
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Xu-li
authors.initials: XL
authors.lastname: Wu
authors.affiliation: Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510405, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Qi
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zheng
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Long
authors.initials: L
authors.lastname: Fan
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Cheng-hui
authors.initials: CH
authors.lastname: Liao
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Chen-yang
authors.initials: CY
authors.lastname: Li
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: He
authors.affiliation: Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510405, China.
authors.forename: Ying-jie
authors.initials: YJ
authors.lastname: Hu
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Hai-qiang
authors.initials: HQ
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China.
authors.forename: Shi-he
authors.initials: SH
authors.lastname: Li
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China. Electronic address: jzhanghappy@szu.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510405, China. Electronic address: zhangfengxue@gzucm.edu.cn.
authors.forename: Feng-xue
authors.initials: FX
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, School of Medicine, Shenzhen University, Shenzhen 518060, China; Institute of Biotherapy, Shenzhen University, Shenzhen 518060, China. Electronic address: hezhendan@126.com.
authors.forename: Zhen-dan
authors.initials: ZD
authors.lastname: He
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology* / Q000633:toxicity; D016207:Cytokines / Q000378:metabolism; D004285:Dogs; D005260:Female; D006027:Glycosides / Q000494:pharmacology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects*; D007251:Influenza, Human / Q000188:drug therapy* / Q000821:virology; D007369:Interferon Inducers / Q000494:pharmacology*; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D031659:Ligustrum / Q000737:chemistry* / Q000633:toxicity; D008168:Lung / Q000821:virology; D018655:Lymphocyte Count; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011654:Pulmonary Edema / Q000188:drug therapy / Q000473:pathology; D012254:Ribavirin / Q000494:pharmacology / Q000627:therapeutic use; D016019:Survival Analysis
chemical_list: D000998:Antiviral Agents; D016207:Cytokines; D006027:Glycosides; D007369:Interferon Inducers; D012254:Ribavirin; D007371:Interferon-gamma
keywords: Endogenous antiviral cytokine; Glycosides; Influenza virus; Interferon-γ; Ligustrum purpurascens