title: Extract of Scutellaria baicalensis inhibits dengue virus replication.
abstract: BACKGROUND
  Scutellaria baicalensis (S. baicalensis) is one of the traditional Chinese medicinal herbs that have been shown to possess many health benefits. In the present study, we evaluated the in vitro antiviral activity of aqueous extract of the roots of S. baicalensis against all the four dengue virus (DENV) serotypes.
  
  
  METHODS
  Aqueous extract of S. baicalensis was prepared by microwave energy steam evaporation method (MEGHE™), and the anti-dengue virus replication activity was evaluated using the foci forming unit reduction assay (FFURA) in Vero cells. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used to determine the actual dengue virus RNA copy number. The presence of baicalein, a flavonoid known to inhibit dengue virus replication was determined by mass spectrometry.
  
  
  RESULTS
  The IC(50) values for the S. baicalensis extract on Vero cells following DENV adsorption ranged from 86.59 to 95.19 μg/mL for the different DENV serotypes. The IC(50) values decreased to 56.02 to 77.41 μg/mL when cells were treated with the extract at the time of virus adsorption for the different DENV serotypes. The extract showed potent direct virucidal activity against extracellular infectious virus particles with IC(50) that ranged from 74.33 to 95.83 μg/mL for all DENV serotypes. Weak prophylactic effects with IC(50) values that ranged from 269.9 to 369.8 μg/mL were noticed when the cells were pre-treated 2 hours prior to virus inoculation. The concentration of baicalein in the S. baicalensis extract was ~1% (1.03 μg/gm dried extract).
  
  
  CONCLUSIONS
  Our study demonstrates the in vitro anti-dengue virus replication property of S. baicalensis against all the four DENV serotypes investigated. The extract reduced DENV infectivity and replication in Vero cells. The extract was rich in baicalein, and could be considered for potential development of anti-DENV therapeutics.
authors.affiliation: Tropical Infectious Disease Research and Education Center (TIDREC), Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Keivan
authors.initials: K
authors.lastname: Zandi
authors.forename: Tong-Hye
authors.initials: TH
authors.lastname: Lim
authors.forename: Nor-Aziyah
authors.initials: NA
authors.lastname: Rahim
authors.forename: Meng-Hooi
authors.initials: MH
authors.lastname: Shu
authors.forename: Boon-Teong
authors.initials: BT
authors.lastname: Teoh
authors.forename: Sing-Sin
authors.initials: SS
authors.lastname: Sam
authors.forename: Mohammed-Bashar
authors.initials: MB
authors.lastname: Danlami
authors.forename: Kim-Kee
authors.initials: KK
authors.lastname: Tan
authors.forename: Sazaly
authors.initials: S
authors.lastname: Abubakar
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D003715:Dengue / Q000821:virology*; D003716:Dengue Virus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D031364:Scutellaria baicalensis / Q000737:chemistry*; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D010936:Plant Extracts; C499814:Scutellaria baicalensis extract