Samenvatting

Alzheimer’s disease is the leading cause of dementia affecting over 46 million worldwide, yet contemporary medication is unable to prevent or slow its neurodegeneration. Recently, fucosterol and saringosterol, two phytosterols from brown macroalgae, have emerged as possible mediators of the disease. However, little is known on the cultivation parameters under which these macroalgae produce increased amounts of phytosterols, limiting their potential bio-refinement. We therefore aimed to investigate the effect of temperature differentiated cultivation on the fucosterol and saringosterol production of the common brown macroalgae Saccharina latissima. The algae were cultivated in triplicate over a period of 21 days at temperatures of 5.3 ± 0.3 ˚C, 9.9 ± 0.4 ˚C and 14 ± 0.2 ˚C with no other independent variables. The samples were saponified in an alkaline environment, followed by liquid-liquid extraction and preparative column chromatography to clean up the extract. The resulting sterol containing fraction was subsequently silylated and analysed by means of GC-FID and GC-MS for quantitative and qualitative purposes respectively.
In all sample groups, fucosterol was found to be the dominant sterol with an average concentration of 1.2 g/kg dry weight. A near significant difference (p=0.0695) was found between the mean fucosterol concentration per temperature group, accompanied by a significant positive correlation (R2=0.4762, p=0.0198) between the two. Saringosterol was tentatively identified and found at concentrations no higher than 2.4 mg/kg dry weight; no effect of temperature on the production of saringosterol was observed. To our best of knowledge, this marks the first time that the effect of temperature on the production of phytosterols in S. latissima is investigated, and we expect this effect to be more pronounced with an increase in sample size. Based on our results, the biorefinery of fucosterol for pharmaceutical applications may be most effectively applied to S. latissima cultures in the upper temperature domain of their natural habitat, while a different avenue must be explored if saringosterol is to be effectively refined.