UBC Theses and Dissertations
Plant virus inhibitors from marine algae Pardee, Keith
This study was the first to evaluate new world algal species for compounds with potential for plant virus chemotherapy. Methanolic extracts from 30 species of marine algae were assayed for antiviral activity against potato virus X (PVX) in local lesion assays using Chenopodium quinoa L. as host. Extracts from six algal species (Fucus gardneri Silva, Alaria nana Schrader, Ralfsia sp. (Berkley), Codium fragile (Suringar) Hariot, Fragilaria oceanica Cleve, Egregia menziesii (Turner) J.E. Areschoug) inhibited PVX infectivity by more than 80%, with a disproportionate number of these extracts coming from the phylum Heterokontophyta. Of the six most active extracts, it is the first time that Fucus gardneri, Ralfsia sp. and Fragilaria oceanica have been reported as sources of antiviral agents. Antiviral activity from the most potent extract, F. gardneri, was selected for phytochemical analysis. Fractionation of the crude extract resulted in the isolation and identification of the polysaccharide alginate as a source of bioactivity. Alginate inhibited potato virus X infectivity by 95%, and preliminary transmission electron microscopy indicates that the mode of action may be related to aggregation of virus particles. Bioactivity in a second fraction was the result of phenolic and amino-based compounds that have yet to be positively identified.
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