[Effect of Yunnan herb Laggera pterodonta against influenza A (H1N1) virus in vitro]

Laggera pterodonta is commonly used for treating influenza in Southwest China, especially in Yunnnan province. The main clinical effects of L. pterodonta include anti-influenza, anti-microbial, anti-inflammatory. To investigate the anti-influenza A (H1N1) virus effect of L. pterodonta, neutralization inhibition and proliferation inhibition tests were performed. MDCK culture method was used to observe the cytopathic effect (CPE) of extracts from L. pterodonta in inhibiting influenza A (H1N1) virus and haemagglutination titre of H1N1 virus in vitro. The culture medium were collected at 24 h, 48 h, 72 h, 96 h, and detected by Real time RT-PCR, in order to compare the effect of different extracts from L. pterodonta on in vitro proliferation of H1N1, virus. The result of neutralization inhibition test showed that hemagglutination titer of ethyl acetate extract were 8 times lower at 72 h; in proliferation inhibition test, hemagglutination titer of ethyl acetate extracts reduced by 2 and 4 times. According to the results of Real time RT-PCR test, the H1N1 inhibition ratio of ethyl acetate extract was 72.5%, while the proliferation inhibition ratio of ethyl acetate extract was 25.3%; as for petroleum ether extracts, the H1N1 inhibition ratio was 60.2%, while the proliferation inhibition ratio was 81.4%. In conclusion, both ethyl acetate extract and petroleum ether extract of L. pterodonta have significant neutralization and direct proliferation inhibition effects on influenza A virus.