Phytochemistry profile and in-vitro cytotoxicity investigation of red algae gracillaria sp. against ht-29 colon cancer cells

Background: Cancer encompasses a heterogeneous group of non-communicable diseases characterized by uncontrolled cellular proliferation that can arise in virtually any organ. Globally, the burden is projected to reach approximately 19.3 million new cases and 10.0 million deaths by 2030. Among these malignancies, colorectal cancer which originating in the colon or rectum, remains one of the most prevalent forms. Varying treatments for colorectal cancer ranging from surgery to chemotherapy are used, which are expensive with low efficacy. Active components from organic materials i.e., marine algae could be utilized as alternative treatment for cancer. One of these marine algae is the red algae species of Gracilaria sp., that is known as a producer of biologically active phytochemicals. Objective: To investigate the phytochemical profile and in vitro cytotoxic properties of the red algae Gracilaria sp. against HT-29 colon cancer cells. Methods: Cleaned and dried Gracilaria sp. biomass was finely pulverized into powder. Sequential multistage maceration was then performed using solvents of increasing polarity of n-hexane, ethyl acetate, and ethanol, yielding the corresponding n-hexane, ethyl acetate, and ethanolic extracts, respectively. These extracts were subsequently subjected to phytochemical screening and thin-layer chromatography (TLC) to characterize their secondary metabolite profiles, followed by evaluation of their cytotoxic activity against HT-29 colon cancer cells using the MTT assay. Results: Seaweed Gracilaria sp. contains secondary metabolites of flavonoids, alkaloids, and triterpenoids. All extracts exhibited measurable cytotoxic effects against HT-29 colon cancer cells. The ethanolic extract demonstrated the highest activity, with an IC₅₀ value of 53.32 μg/mL. In contrast, the ethyl acetate and n-hexane extracts displayed comparatively weak cytotoxicity, with IC₅₀ values of 107.58 μg/mL and 180.65 μg/mL, respectively. Conclusion: Red algae of Glacilaria sp. should be further investigated as a new candidate of anti-colon cancer agent.