title: Effects of Clinacanthus siamensis leaf extract on influenza virus infection.
abstract: Ethanolic extracts of 20 medicinal plants were screened for influenza virus NA inhibition and in vitro antiviral activities using MDCK cells in an MTT assay. The vaccine proteins of influenza virus A/New Caledonia/20/99 (H1N1), mouse-adapted influenza virus A/Guizhou/54/89 (A/G)(H3N2) and mouse-adapted influenza virus B/Ibaraki/2/85 (B/I) were used in the NA inhibition assay, and mouse-adapted influenza viruses A/PR/8/34 (H1N1), A/G and B/I were used in the in vitro antiviral assay. The results of the in vitro antiviral assay indicated that the A/G virus was the most susceptible and an extract of the leaf of CS possessed the highest in vitro anti-A/G virus activity (41.98%). Therefore, the A/G virus and the CS extract were selected for studying in vivo anti-influenza virus activity. BALB/c mice were treated with CS extract (100 mg/kg per day, 5 times) orally from 4 hr before to 4 days after infection. CS extract elicited significant production of anti-influenza virus IgG(1) antibody in BAW and increased mouse weight compared to oseltamivir (0.1 mg/kg per day) on day 19 or water on days 17-19 of infection. Moreover, CS extract produced a higher anti-influenza virus IgA antibody level in BAW compared to oseltamivir, and a tendency towards an increase in anti-influenza virus IgA compared to water was shown. The results suggest that CS extract has a protective effect against influenza virus infection.
authors.affiliation: Faculty of Pharmaceutical Sciences, Chulalongkorn University, 254 Phayathai Road, Wangmai, Pathumwan, Bangkok 10330, Thailand. mali.w@chula.ac.th
authors.forename: Mali
authors.initials: M
authors.lastname: Wirotesangthong
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nagai
authors.forename: Haruki
authors.initials: H
authors.lastname: Yamada
authors.forename: Surattana
authors.initials: S
authors.lastname: Amnuoypol
authors.forename: Chutichot
authors.initials: C
authors.lastname: Mungmee
mesh_terms: D027901:Acanthaceae / Q000737:chemistry*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000998:Antiviral Agents / Q000627:therapeutic use*; D001835:Body Weight; D002460:Cell Line; D005260:Female; D053118:Influenza A Virus, H1N1 Subtype; D053122:Influenza A Virus, H3N2 Subtype; D009981:Influenza B virus; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000188:drug therapy*; D053139:Oseltamivir / Q000627:therapeutic use; D010936:Plant Extracts / Q000627:therapeutic use*; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry
chemical_list: D000914:Antibodies, Viral; D000998:Antiviral Agents; D010936:Plant Extracts; D053139:Oseltamivir