Bioassay-Guided Isolation and Detection of a Cytotoxic Compound Known as Fucosterol from the Peruvian Lessonia Trabeculata Seaweed

Lessonia trabeculata, called “Aracanto”, is a brown macroalga distributed in submarine, exposed and semiexposed rocky environments, and scattered along the Peruvian coast forming continuous grasslands. Despite its abundance in the Peruvian coastline, little or no importance has been given to its study, especially in the extraction of its secondary metabolites. In this work, we screened Lessonia trabeculata extracts for cytotoxic activity against human breast cancer cells. Only hexane extract was observed to be active against these cells. Both the chloroform and methanol extract were inactive. Bioassay-guided fractionation of the L. trabeculata hexane extract resulted in the isolation and identification of fucosterolusing NMR spectroscopy. The IC50 measured for hexane extract from L. trabeculata was 129 μg/mL and 75 μM for fucosterol, compared to mithramycin, a positive control. This study on the secondary metabolites of the Peruvian seaweed L. trabeculata is the first of its kind. The data obtained represents an interesting doorway for further studies.