Anti-Influenza Viral Flavonoids from Persicaria filiforme
Persicaria filiforme Nakai, which belongs to the family Polygonaceae, is a perennial herb growing in mountains area of Korea . It has been used as a traditional Chinese medicine for the treatment of various bleeding, diarrhea, dysentery, and stomachache . In the course of a search for anti-influenza viral compounds from natural products, we have found that the methanol extract of P. filiforme has anti-viral activity against influenza A virus. To date, there are no reports on the phytochemical constituents and biological activities of P. filiforme. A new flavonol glycoside and eight known flavonoids were isolated from the EtOAc and n-BuOH fractions of P. filiforme. The known compounds, quercitrin (2), juglanin (3), avicularin (4), afzelin (5), quercetin (6), kaempferol (7), quercitrin 2''-O-gallate (8) and quercitrin 3''-O-gallate (9) were identified by comparing their spectral data with literature values. The structure of a new flavonol glycoside (1), named persicarioside A, was determined as quercetin 3-O-β-D-apiofuranosyl-(1→2)-α-L-rhamnopyranoside from spectral data and chemical evidence. The anti-influenza viral activity of the isolates 1-9 were evaluated using cytopathic effect (CPE) inhibition assay against influenza A/NWS/33 (H1N1) virus [3, 4]. Compounds 1, 2, and 7 showed antiviral activity. The anti-viral compounds were subjected to inhibitory activity against neuraminidase in a virus. The effect of compounds was evaluated using neuraminidase inhibition assay in influenza A/NWS/33 virus . The activity of neuraminidase decreased significantly by tested compounds, however half reduction of enzymatic activity was shown at relatively high concentration.
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2. Zhonghuabencao Compilation Committee (1999) Zhonghuabencao (2). Shanghai Science and Technological Publisher. Shanghai.
3. Player MR et al. (1998) Proc Natl Acad Sci USA 95: 8874–8879.
4. Jeong HJ et al. (2009) Bioorganic & Medicinal Chemistry 17: 6816–6823.
5. Song J-M et al. (2005) Antiviral Research 68: 66–74.