title: The in vitro antiviral property of Azadirachta indica polysaccharides for poliovirus.
abstract: BACKGROUND
  Azadirachta indica A. Juss, popularly known as neem, has been extensively used in Ayurvedic medicine by Indian population for over 2000 years. It is used traditionally for the healing of various diseases. Natural products and their derivatives provide an excellent source for new anti-viral drugs.
  
  
  OBJECTIVE
  The present study aims at evaluating the activity of two polysaccharides (P1 and P2) isolated from the leaves of Azadirachta indica and their chemical sulfated derivatives (P1S and P2S) against poliovirus type 1 (PV-1).
  
  
  METHODS
  The cytotoxicity of the compounds was analyzed by MTT and the antiviral effect was determined by plaque reduction assay in different protocols.
  
  
  RESULTS
  The polysaccharides did not show any cytotoxic effects on HEp-2 cells at the highest tested concentration (200 μg/ml) and exhibited significant antiviral activity with inhibitory concentrations (IC₅₀) of 80 μg/ml, 37.5 μg/ml, 77.5 μg/ml, and 12.1 μg/ml for P1, P1S, P2 and P2S, respectively, and the selectivity indexes (SI) ranged from 18 to 131.9. The compounds demonstrated better inhibitory effect when added concomitantly with the virus infection with a dose-dependent curve inhibition. Lesser effect was observed when the compounds were added after viral infection and the least effect at pre-treatment.
  
  
  CONCLUSIONS
  We suggested that the polysaccharides obtained from Azadirachta indica act against PV-1 by inhibiting the initial stage of viral replication. Importantly, original polysaccharides showed better virucidal effect than their sulfated derivatives at all tested concentrations. This study provides a scientific basis for the past and present ethnomedical uses of this plant.
authors.affiliation: Departamento de Microbiologia, CCB, Universidade Estadual de Londrina, Caixa Postal 6001, 86051-990 Londrina, PR, Brazil.
authors.forename: Ligia Carla
authors.initials: LC
authors.lastname: Faccin-Galhardi
authors.forename: Kristie Aimi
authors.initials: KA
authors.lastname: Yamamoto
authors.forename: Sayani
authors.initials: S
authors.lastname: Ray
authors.forename: Bimalendu
authors.initials: B
authors.lastname: Ray
authors.forename: Rosa Elisa
authors.initials: RE
authors.lastname: Carvalho Linhares
authors.forename: Carlos
authors.initials: C
authors.lastname: Nozawa
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D031601:Azadirachta; D045744:Cell Line, Tumor; D006801:Humans; D018515:Plant Leaves / Q000737:chemistry; D017955:Poliovirus / Q000187:drug effects* / Q000502:physiology; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D011134:Polysaccharides