The complement system plays a crucial role in the elimination of invading pathogens and generation of an optimal host response. However, the inappropriate activation of complement system may cause some life-threatening symptoms including acute respiratory distress syndrome (ARDS). In order to demonstrate the effective constituents of traditional Chinese medicines (TCMs) with functions of heat-clearing and detoxification and to obtain natural anticomplement agents from TCMs for prevention and treatment of the complement-associated diseases, bioactivity-guided fractionation and isolation was thus performed and led to the isolation and characterization of some valuable anticomplement constituents from several TCMs.
The Bupleurum polysaccharides showed anti-complementary activity and exhibited beneficial effects on the acute lung injury (ALI) in rats and mice. The polysaccharides obtained from Houttuynia cordata (HCP) exhibited anti-complementary and antipyretic activities, and attenuated the lipopolysaccharide-induced ALI in mice and rats as well. The interesting finding is that HCP exhibited protective effect on mice infected by influenza A virus (H1N1), although it had no direct inhibition against the virus. In addition, the total flavonoids obtained from Houttuynia cordata showed antiviral activity against influenza virus in vitro and exerted synergistic protective effects on the mice with virus infection in combination with HCP. The flavonoids enriched from Scutellariae Radix showed beneficial effects on the H1N1-induced ALI in mice as well, with their in vivo metabolic activation by gut microbiota.
Our studies demonstrated that the polysaccharides and flavonoids from the traditional Chinese medicines are valuable anticomplement agents for prevention and treatment of ARDS, severe acute respiratory syndrome (SARS), influenza and bird flu.
Acknowledgements : This work was supported by the National Natural Science Foundation of China (NO. 81330089 and 30925042) .