Beneficial effects of Houttuynia cordata polysaccharides on “two-hit” acute lung injury and endotoxic fever in rats associated with anti-complementary activities

Lu, Yan; Jiang, Yun; Ling, Lijun; Zhang, Yunyi; Li, Hong; Chen, Daofeng

Anti-complementary activity through the classical pathway was studied based on Mayer's modified method 25 with BBS as the buffer. As the complement source, the 1:80 diluted serum of guinea pig was chosen to give sub-maximal lysis in the absence of complement inhibitors. CHCP and heparin, used as the positive control, were dissolved in BBS. Different dilutions of samples (200 μL) were incubated with 200 μL guinea pig serum, 100 μL sheep erythrocytes (4.0 × 10 8 cells/mL) and 100 μL rabbit antisheep erythrocyte antibody at 37°C for 30 min. Then the reaction mixture was centrifuged at 1800 × g for 5 min. Optical density (OD) of the supernatant was measured at 405 nm. The sample control of each dilution, the blank control and 100% lysis control were all prepared under the same conditions. The corrected absorbance of each dilution of CHCP sample was obtained by subtracting the absorbance of the sample control from each value. The activity was determined by means of triplicate measurements and expressed as the 50% inhibition (CH 50 ).