Detection of in vitro Inhibitory Effects of Boehmeria nivea Leaves Extracts on Influenza A Virus （H1N1）and Its Antioxidant Activity / 中国药房

ABSTRACT

OBJECTIVE： To study the in vitro inhibitory effects and antioxidant activity of different solvent extracts of Boehmeria nivea leaves against influenza A virus（H1N1）， and to expand the medicinal parts of B. nivea and develop natural antiviral and antioxidant drugs. METHODS： The leaves of B. nivea were extracted with 95％ ethanol. The ethanol extract was dissolved by water heating， and extracted with different solvents to obtain petroleum ether phase， trichloromethane phase， ethyl acetate phase， n-butanol phase and aqueous phase extracts of B. nivea leaves. The toxicity of aqueous extract of B. nivea leaves （50-400 μg/mL） on Madin-Darby canine kidney （MDCK） cell line was investigated. Using ribavirin as positive control， MDCK cells were attacked by influenza A virus（H1N1）. Western blotting assay was used to detect the expression of nucleoproteins （NP） in viral infected cells after treated with same concentrations of petroleum ether phase， trichloromethane phase， ethyl acetate phase， n-butanol phase and aqueous phase extracts of B. nivea leaves （100 μg/mL）， different concentrations of aqueous phase extract solution of B. nivea leaves （50， 100， 200， 400 μg/mL） and different concentrations of ribavirin solution （0.31， 0.63， 1.25 μg/mL）. Using vitamin C as a positive control， hydroxyl radical（·OH） scavenging test， DPPH radical scavenging test and reduction test were used to investigate in vitro antioxidant activity of the extracts. RESULTS： Aqueous phase extract of B. nivea leaves with concentration less than 400 μg/mL was nontoxic to MDCK cells. The petroleum ether phase， trichloromethane phase， ethyl acetate phase and aqueous phase extracts at 100 g/mL could significantly reduce the expression of NP protein in influenza A virus（H1N1） infected cells （P＜0.01）. Different concentrations （50-400 μg/mL） of aqueous extract could significantly reduce the protein expression of NP （P＜0.01） in concentration-dependent manner. The in vitro antioxidant activity of petroleum ether phase and ethyl acetate phase was similar to that of vitamin C. CONCLUSIONS： B. nivea leaves extract have better anti-influenza A virus（H1N1） effects in vitro， and the extracts of petroleum ether phase and ethyl acetate phase show good antioxidant activity in vitro.