The
San Wu Huangqin Decoction (SWHD), a
traditional Chinese medicine formula, is used to treat colds caused by exposure to wind-pathogen,
hyperpyrexia,
infectious diseases and
cancer; moreover, it is used for detoxification. The individual herbs of SWHD, such as Sophora flavescens and Scutellaria baicalensis, exhibit a wide spectrum of
antiviral, anti-inflammatory, antibacterial, anticancer and other properties. The Chinese compound formula of SWHD is composed of S. flavescens, S. baicalensis and Rehmannia glutinosa. However, the effect of SWHD on the influenza virus (IFV) and its mechanism remain unknown. The aim of this study was to evaluate, for the first time, whether SWHD could be used to treat
influenza. Results showed that SWHD could effectively inhibit
influenza A/PR/8/34 (H1N1) virus at different stages of viral replication (confirmed through
antiviral effect assay, penetration assay, attachment assay and internalization assay) in vitro. It could reduce the
infection of the virus in a dose- and time-dependent manner, as confirmed by observing the cell cytopathic effect and calculating the cell viability (p < 0.05). SWHD demonstrated better
antiviral activity than
oseltamivir in the evaluation of
antiviral prophylaxis on
influenza (p < 0.05). The
antiviral activity of SWHD may be related to its regulation ability on the immune system. Western blot, real-time polymerase chain reaction and indirect immunofluorescence assay showed that the expression of the four target
viral proteins of the IFV (namely, haemagglutinin (HA),
neuraminidase (NA),
nucleoprotein (NP) and matrix-2 (M2)) reduced significantly (p < 0.05). Moreover, SWHD (23.40 and 11.70 g/kg) significantly alleviated the clinical signs, reduced the mortality and increased the survival time of infected mice (p < 0.05). The lung index, virus titres, pathological changes in lung tissues and the expression of key
proteins of the IFV in mice also decreased (p < 0.05). In conclusion, SWHD possessed anti-
influenza activity. This work provided a new view of complementary
therapy and
drug discovery for clinical treatment.