14-Deoxy-11,12-didehydroandrographolide attenuates excessive inflammatory responses and protects mice lethally challenged with highly pathogenic A(H5N1) influenza viruses.

Traditional Chinese medicine (TCM) has been an excellent treasury for centuries' accumulation of clinical experiences, which deserves to be tapped for potential drugs and improved using modern scientific methods. 14-Deoxy-11,12-didehydroandrographolide (DAP), a major component of an important TCM named Andrographis paniculata, with non-toxic concentration of 1000 mg/kg/day, effectively reduced the mortality and weight loss of mice lethally challenged with A/chicken/Hubei/327/2004 (H5N1) or A/PR/8/34 (H1N1) influenza A viruses (IAV) when initiated at 4 h before infection, or A/duck/Hubei/XN/2007 (H5N1) when initiated at 4 h or 48 h before infection, or 4 h post-infection (pi). DAP (1000 or 500 mg/kg/day) also significantly diminished lung virus titres of infected mice when initiated at 4 h or 48 h before infection, or 4 h pi. In the infection of A/duck/Hubei/XN/2007 (H5N1), DAP (1000 mg/kg/day) treatment initiated at 48 h before infection gained the best efficacy that virus titres in lungs of mice in log10TCID50/mL reduced from 2.61 ± 0.14 on 3 days post-infection (dpi), 2.98 ± 0.17 on 5 dpi, 3.54 ± 0.19 on 7 dpi to 1.46 ± 0.14 on 3 dpi, 1.86 ± 0.18 on 5 dpi, 2.03 ± 0.21 on 7 dpi. Moreover, DAP obviously alleviated lung histopathology and also strongly inhibited proinflammatory cytokines/chemokines expression. The mRNA levels of TNF-α, IL-1ß, IL-6, CCL-2/MCP-1, IFN-α, IFN-ß, IFN-γ, MIP-1α, MIP-1ß in lungs of A/duck/Hubei/XN/2007 (H5N1)-infected mice and serum protein expression of TNF-α, IL-1ß, IL-6, CCL-2/MCP-1 and CXCL-10/IP-10 in mice infected with all the three strains of IAV were all significantly reduced by DAP. Results demonstrated that DAP could restrain both the host intense inflammatory responses and high viral load, which were considered to contribute to the pathogenesis of H5N1 virus and should be controlled together in a clinical setting. Considering the anti-inflammatory and anti-IAV activities of DAP, DAP may be a promising active component obtained from A. paniculata, which can be further investigated as a useful constitute of curative strategies in the future against IAV, the H5N1 strains in particular.

14-Deoxy-11,12-dehydroandrographolide exerts anti-influenza A virus activity and inhibits replication of H5N1 virus by restraining nuclear export of viral ribonucleoprotein complexes.

The highly pathogenic avian influenza H5N1 virus has become a worldwide public health threat, and current antiviral therapies have limited activity against the emerging, resistant influenza viruses. Therefore, effective drugs with novel targets against influenza A viruses, H5N1 strains in particular, should be developed. In the present study, 14-deoxy-11,12-dehydroandrographolide (DAP), a major component of the traditional Chinese medicine Andrographis paniculata, exerted potent anti-influenza A virus activity against A/chicken/Hubei/327/2004 (H5N1), A/duck/Hubei/XN/2007 (H5N1), A/PR/8/34 (H1N1), A/NanChang/08/2010 (H1N1) and A/HuNan/01/2014 (H3N2) in vitro. To elucidate the underlying mechanisms, a series of experiments was conducted using A/chicken/Hubei/327/2004 (H5N1) as an example. Our results demonstrated that DAP strongly inhibited H5N1 replication by reducing the production of viral nucleoprotein (NP) mRNA, NP and NS1proteins, whereas DAP had no effect on the absorption and release of H5N1 towards/from A549 cells. DAP also effectively restrained the nuclear export of viral ribonucleoprotein (vRNP) complexes. This inhibitory effect ought to be an important anti-H5N1 mechanism of DAP. Meanwhile, DAP significantly reduced the upregulated expression of all the tested proinflammatory cytokines (TNF-α, IL-6, IL-8, IFN-α, IL-1ß and IFN-ß) and chemokines (CXCL-10 and CCL-2) stimulated by H5N1. Overall results suggest that DAP impairs H5N1 replication at least in part by restraining nuclear export of vRNP complexes, and the inhibition of viral replication leads to a subsequent decrease of the intense proinflammatory cytokine/chemokine expression. In turn, the effect of modification of the host excessive immune response may contribute to overcoming H5N1. To our knowledge, this study is the first to reveal the antiviral and anti-inflammatory activities of DAP in vitro against H5N1 influenza A virus infection.