Effects of baicalein on Sendai virus in vivo are linked to serum baicalin and its inhibition of hemagglutinin-neuraminidase.
ABSTRACT Parainfluenza viruses are significant respiratory-tract pathogens that are notorious for infecting children. However, there are no clinical drugs to control the infection caused by these viruses. Sendai virus (SeV) belongs to the family Paramyxoviridae and causes fatal pneumonia in mice, its natural host. Baicalein is a flavonoid derived from the root of Scutellaria baicalensis, which is a traditional Chinese medicine that has been used for hundreds of years and has demonstrated a variety of biological activities. Our findings reveal that oral administration of baicalein to mice infected with Sendai virus results in a significant reduction in virus titers in the lungs and protection from death. The in vivo inhibitory effects of baicalein on Sendai virus are determined by baicalin in the serum. The mean IC(50) of baicalin was 0.71 μg/ml in an HA inhibition assay and 3.22 μg/ml in an NA inhibition assay. The mean IC(50) of baicalin in a CPE assay was measured to be 0.70 μg/ml, and significant inhibition was observed in a plaque assay at a concentration of 1.6 μg/ml baicalin in overlay medium, which suggests that baicalein is a potential anti-parainfluenzaviral agent in vivo.
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ABSTRACT: This study rated antiviral activity of Scutellaria baicalensis Georgi (S. baicalensis) extracts against influenza A virus subtypes, for example, pandemic 2009 H1N1, seasonal H1N1 and H3N2. Ethyl acetate (EtOAc) and chloroform extracts inhibited in vitro neuraminidase (NA) enzymatic activity and viral replication more than methanol (MeOH) extract. EtOAc extract demonstrated NA inhibition IC50 values ranging from 73.16 to 487.40 μg/mL and plaque reduction IC50 values ranging from 23.7 to 27.4 μg/mL. Chloroform extract showed antiviral activities with plaque reduction IC50 values ranging from 14.16 to 41.49 μg/mL Time-of-addition assay indicated that EtOAc and chloroform extracts also significantly inhibited virus yields after infection. HPLC analysis demonstrated that baicalin was dominant in the MeOH extract; baicalein and chrysin were rich in the EtOAc and chloroform extracts. Molecular simulation revealed baicalein hydrogen bonding with Glu277 as well as hydrophobic and Van der Waals interactions with Ile222, Arg224, Ser246, and Tyr347 in NA1 active sites of NA1. Baicalein inhibited in vitro replication of influenza A viruses pandemic 2009 H1N1 (IC50 = 0.018 μM) and seasonal 2007 H1N1 using plaque reduction assays. A combination of low-dose baicalein with other anti-influenza agents could be applicable for development of alternative remedies treating influenza A virus infection.Evidence-based Complementary and Alternative Medicine 01/2013; 2013:750803. · 1.72 Impact Factor
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ABSTRACT: Japanese encephalitis (JE), a mosquito-borne viral disease, is endemic to the entire east and southeast Asia, and some other parts of the world. Currently, there is no effective therapeutic available for JE; therefore, finding the effective antiviral agent against JEV replication is crucial. In the present study, the in vitro antiviral activity of baicalein and quercetin, two purportedly antiviral bioflavonoids, was evaluated against Japanese encephalitis virus (JEV) replication in Vero cells. Anti-JEV activities of these compounds were examined on different stages of JEV replication cycle. The effects of the compounds on virus replication were determined by foci forming unit reduction assay (FFURA) and quantitative RT-PCR. Baicalein showed potent antiviral activity with IC50 = 14.28 µg/mL when it was introduced to the Vero cells after adsorption of JEV. Quercetin exhibited weak anti-JEV effects with IC50 = 212.1 µg/mL when the JEV infected cells were treated with the compound after virus adsorption. However, baicalein exhibited significant effect against JEV adsorption with IC50 = 7.27 µg/mL while quercetin did not show any anti-adsorption activity. Baicalein also exhibited direct extracellular virucidal activity on JEV with IC50 = 3.44 µg/mL. However, results of quantitative RT-PCR experiments confirmed the findings from FFURA. This study demonstrated that baicalein should be considered as an appropriate candidate for further investigations, such as the study of molecular and cellular mechanism(s) of action and in vivo evaluation for the development of an effective antiviral compound against Japanese encephalitis virus.International Journal of Molecular Sciences 12/2012; 13(12):16785-16795. · 2.46 Impact Factor