Anti-Influenza Activity of Medicinal Material Extracts from Qinghai-Tibet Plateau.

To discover sources for novel anti-influenza drugs, we evaluated the antiviral potential of nine extracts from eight medicinal plants and one mushroom ( Avena sativa L., Hordeum vulgare Linn. var. nudum Hook. f., Hippophae rhamnoides Linn., Lycium ruthenicum Murr., Nitraria tangutorum Bobr., Nitraria tangutorum Bobr. by-products, Potentilla anserina L., Cladina rangiferina (L.) Nyl., and Armillaria luteo-virens ) from the Qinghai-Tibetan plateau against the influenza A/H3N2 virus. Concentrations lower than 125 μg/mL of all extracts demonstrated no significant toxicity in MDCK cells. During screening, seven extracts ( A. sativa , H. vulgare , H. rhamnoides , L. ruthenicum , N. tangutorum , C. rangiferina , and A. luteo-virens ) exhibited antiviral activity, especially the water-soluble polysaccharide from the fruit body of the mushroom A. luteo-virens . These extracts significantly reduced the infectivity of the human influenza A/H3N2 virus in vitro when used at concentrations of 15.6-125 μg/mL. Two extracts ( N. tangutorum by-products and P. anserina ) had no A/H3N2 virus inhibitory activity. Notably, the extract obtained from the fruits of N. tangutorum and N. tangutorum by-products exhibited different anti-influenza effects. The results suggest that extracts of A. sativa , H. vulgare , H. rhamnoides , L. ruthenicum , N. tangutorum , C. rangiferina , and A. luteo-virens contain substances with antiviral activity, and may be promising sources of new antiviral drugs.