Presence of phenolic compounds in acetone extracts from Saccharina latissima and their antibacterial and ferrous ion-chelating activities

Abstract

An increased interest to use biomass for alternative fuels has led to a competition between crops for energy production and food. The larger demand for food crops is causing a growing concern about food scarcity, food price as well as pollution of agricultural land. This has led to researchers looking at algae for a solution. Algae provides a significantly higher production yield per unit area compared to terrestrial biomass and contains polysaccharides, proteins, lipids as well as other high value products. They can also be cultivated in most forms of water, sea water and municipal waste water being the most interesting. These qualities combined with the lack of competition with food production make algae an interesting area to explore. The aim of this project was to investigate acetone extracts from the seaweed Saccharina latissima for the presence of phenolic compounds, which have potential future uses as food preservation additives and in the medicinal sector. Apart from investigating the presence of phenolic compounds, the aim was also to investigate the extracts’ ferrous ion-chelating- and anti-bacterial activities as well as the difference between three seasonal variations (June, August and October) and three locations (Ulvillarna, Ursholmen and Yttre Vattenholmen). There were, however, storms during October resulting in Ulvillarna and Ursholmen having no seaweeds left. Extraction was done with 70 % aqueous acetone using freeze dried algae biomass. Quantification of total phenolic content was done with the folin-ciocalteu reagent. Ferrous ion-chelating activity was done using FeCl2 and ferrozine, and the anti-bacterial activity was done on two bacterial strains, Escherichia coli and Klebsiella oxytoca, using filter discs dotted with algae extract and put on bacterial lawns in petri dishes. The generally largest concentration of phenolic content was found in June and in samples from the collection site Yttre Vattenholmen. Yttre Vattenholmen extracts from October had close to the same average amount of phenolic content to those of August. The ferrous ion-chelating activity of the extracts were the strongest during October but showed no clear linear correlation with total phenolic content. The anti-bacterial activity did not show any clear growth inhibiting effect on either bacterial strain.