Bioactive from Ulva lactuca and Ulva fasciata: Structural insights and mechanistic roles in colon cancer therapy

Abstract

Colon cancer is one of the causes of the cancer-related morbidity and mortality on the global scale, and it is crucial to develop safe and effective therapy solutions. Marine green macroalgae, especially species of Ulva have emerged as important sources of structurally diverse bioactive macromolecules with anticancer potential. This review summarizes the existing available information regarding the structure, functionality, and translational use of green algal macromolecules in colon cancer management. Ulvans are sulfated heteropolysaccharides enriched with rhamnose and uronic acids that induce apoptosis, arrest cell cycle, and block oncogenic signaling pathways such as Wnt/b-catenin, PI3K/Akt/mTOR, or NF-kB. The peptides, polyphenols, and polyunsaturated fatty acids derived in Ulva have complementary effects, as they increase antioxidant defense, inhibit chronic inflammation, and manipulate immune responses. The structure-function relationships reveal the importance of sulfate replacement, molecular weight, and monosaccharide composition to define bioactivity. Although in vitro and in vivo experiments prove that selective, low-toxicity, cytotoxicity is restricted to colon cancer cells and not to normal tissue, there is limited clinical validation. Some of the major challenges involve low solubility, absence of standardized procedures of extraction, and inadequate pharmacokinetic characterization. This review highlights the therapeutic potential of green algal macromolecules, highlights translational challenges, and suggests future efforts on developing functional foods, nutraceuticals, and adjuvant therapies against colon cancer.