The cytotoxic activity of extracts of the brown alga Cystoseira tamariscifolia (Hudson) Papenfuss, against cancer cell lines changes seasonally

Abstract

Brown seaweeds have been highlighted for their abundant production of bioactive substances that may provide novel drugs or drug scaffolds for a range of diseases, particularly cancer. Indeed, a number of promising compounds that can modulate growth arrest or apoptosis have already been isolated. As previous work has highlighted seasonal differences in concentrations of secondary metabolites, this study aimed to evaluate seasonal variation in the cytotoxic anticancer activity of Cystoseira tamariscifolia extracts. Primary and secondary metabolites were measured using colourimetric techniques and extracts were exposed to human leukaemia, HL60 and THP-1, and human prostate cancer PC3 cell lines in vitro, and cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The results confirm a large but inconsistent seasonal variation in the concentrations of biomolecules, although, generally, levels were higher in spring and summer. IC50 values for cytotoxicity also showed variability both seasonally and with extraction protocol, but again, this was inconsistent. These data suggest that when collecting brown algae in order to isolate novel bioactive compounds, repeated sampling across annual or biotic cycles of the seaweed and the use of multiple solvent extraction methods could give a greater possibility of discovering bioactive lead compounds.