Algae from Portuguese Coast Presented High Cytotoxicity and Antiproliferative Effects on an In vitro Model of Human Colorectal Cancer

Background: The marine environment has shown to be an interesting source of new antitumor agents, representing an important tool in cancer research. Objective: The aim of this study was to evaluate the antitumor activities of 12 algae from Peniche coast (Portugal) on an in vitro model of human colorectal cancer (Caco‑2 cells). Materials and Methods: The antitumor potential was accessed by evaluating Caco‑2 cell’s viability and proliferation through the 3‑[4, 5‑dimethylthiazol‑2‑yl]‑2, 5‑diphenyl tetrazolium bromide and calcein‑AM methods. Results: The dichloromethane extracts of Asparagopsis armata and Sphaerococcus coronopifolius induced the highest decrease on cell’s viability (1 mg/mL; 24 h), 98.96% ± 0.39% and 98.08% ± 0.89%, respectively, followed by the methanolic extracts of S. coronopifolius (96.47% ± 1.26%) and A. armata (92.68% ± 1.17%). Regarding cell proliferation, the highest decrease of Caco‑2 cell’s proliferation (1 mg/mL; 24 h) was induced by the dichloromethane extract of A. armata (100% ± 0.48%), S. coronopifolius (99.04 ± 0.51%), and Plocamium cartilagineum (95.05% ± 1.19%). The highest potency was shown by the dichloromethane extract of S. coronopifolius in both, cytotoxicity and antiproliferative tests, with an IC50 of 21.3 and 36.5 µg/mL, respectively. Conclusion: The extracts of A. armata and S. coronopifolius are promising sources of new bioactive molecules with application in cancer therapeutics.