Lysiphyllum strychnifolium (Craib) A. Schmitz extract, a novel neuraminidase inhibitor of avian influenza virus subtype H5N1

Abstract

The leaves and stems of Lysiphyllum strychnifolium (Craib) A. Schmitz (Fabaceae family) have been traditionally used in Thailand for detoxification and to treat pesticide poisoning in humans. To uncover novel uses of L.strychnifolium, the possible antiviral properties against avian influenza virus A, strain H5N1, were explored in this study. The ethanolic extracts of L.strychnifolium leaves and stems showed good inhibitory activities against H5N1 neuraminidase. Such activities have not been previously reported for this plant. Aqueous extracts did not show any inhibition. Thereafter, the anti-neuraminidase activities of ethanolic extracts were evaluated using fluorometric determination via a MUNANA-based enzyme inhibition assay. Ethanolic extracts of both stems and leaves showed good inhibitory activities against neuraminidase from Influenza A H5N1 with IC50 values of 55.3 and 70.0 μg/mL, respectively. Moreover, anti-bacterial activities of aqueous and ethanolic extracts of L.strychnifolium leaves and stems were tested using the disc diffusion method. All extracts showed broad antibacterial activities against both Gram positive and Gram negative bacterial strains. Phytochemical constituents of all extracts were identified through Gas Chromatography - Mass Spectrometry (GC-MS) and revealed some compounds such as Methyl-p-hydrozybenzoate; Mome inositol; n-Hexadecanoic acid; Tetradecanamide; (Z)-9-Octadecanamide; 1,2,3,-Benzenetriol; Methylparaben; 4-(4-Hydroxyphenyl)-2-butanone; n-Hexadecanoic acid; Ethyl hexadecanoate; Phytol; (Z)-9-Octadecanoic acid, and Octadecanoic acid. This is the first report of neuraminidase inhibitor against Influenza A H5N1 and antibacterial activities derived from L.strychnifolium extracts. The authors suggest that this plant is an alternative source for treatment against influenza viruses and potential antibiotic agent.