Natural extracts from brown seaweeds native to the UK have been shown to have antiviral activities that could be useful in producing biocides that help prevent the spread of these diseases. However, these extracts contain a range of different components which vary in composition between different brown seaweeds and sometimes between location of harvest and season. This project seeks to identify the most active components from the brown seaweeds and provide an effective means to optimise the extraction of these components into effective natural antiviral agents.