The Effects of Frondanol, a Non-Polar Extract of the Atlantic Sea Cucumber, in Colon Cancer Cells

<b>Background:</b> Colorectal cancer (CRC) is the second leading cause of cancer-related mortality worldwide. The search for effective, new antineoplastic drugs with fewer side effects for the treatment of CRC continues, with marine-derived compounds emerging as promising candidates. <b>Objectives:</b> This study investigates the anticancer potential of Frondanol, a nutraceutical derived from the Atlantic Sea cucumber <i>Cucumaria frondosa</i>, known for its potent anti-inflammatory properties. <b>Methods:</b> Two human CRC cell lines, Caco-2 and HT-29, were used to test the effects of Frondanol using various in vitro approaches. <b>Results:</b> Frondanol significantly inhibited cell viability in a dose- and time-dependent manner. At a 1:10,000 dilution, viability decreased to around 30% in Caco-2 and 20% in HT-29 after 24 h, dropping to nearly 5% at 48 h. Furthermore, a clonogenic assay showed around 50% reduction in colony formation in both cell lines. Flow cytometry-based Annexin V staining revealed that Frondanol increased early apoptosis to ~5.2% in Caco-2 and ~9.4% in HT-29 cells, while cell cycle analysis showed accumulation of the sub G0 (apoptotic) phase increasing from 1.5% to 14.7% (Caco-2) and from 1.9% to 23.8% (HT-29). At the molecular level, Frondanol treatment significantly decreased anti-apoptotic protein B-cell lymphoma (Bcl)-2 expression while increasing the expression of the proapoptotic protein Bcl-2-associated X-protein. Additionally, Frondanol markedly induced cytochrome c release from the mitochondria and activated caspase-9, caspase-7, and caspase-3 after treatment, alongside cleavage of the caspase-3 substrate poly (ADP-ribose) polymerase. Frondanol inhibited 5-lipoxygenase activity, further contributing to its anticancer effects. <b>Conclusions:</b> In conclusion, Frondanol inhibits CRC cell proliferation and induces apoptosis through the mitochondrial pathway in vitro, suggesting that it is a potential nutraceutical for the prevention of human colorectal cancer or a valuable source of anticancer compounds.