Anticancer and Cancer Stem Cell Inhibitory Effects of Eleutherococcus gracilistylus Ethanol Extracts in Colorectal Cancer Models

Background Eleutherococcus gracilistylus (Seom-ogalpi), a rare deciduous shrub from the Araliaceae family native to Korea, is known for its antioxidant and anticancer properties. The increasing incidence of colorectal cancer, particularly among young adults in Korea, highlights the urgent need for targeted therapies. This is especially important for addressing cancer stem cells, which play a critical role in tumor progression and contribute to treatment resistance. This study investigates the anticancer effects of various parts of E. gracilistylus —leaves, branch, roots, fruits—using ethanol extracts at different concentrations to identify the most biologically active components against colorectal cancer cells and cancer stem cells. Methods E. gracilistylus was collected from Jeju Island, South Korea, and the absolute ethanol extract of fruit was fractionated into n-hexane, dichloromethane, ethyl acetate, butanol, and water fractions. HT-29 and HCT-116 colorectal cancer cell lines were cultured in DMEM with 10% FBS at 37°C, and tumorspheres were formed in ultra-low attachment plates and assessed using the NICE scan program. Cell proliferation was measured using the EZ-Cytox assay, and apoptosis was analyzed via flow cytometry. Gene expression was evaluated using RT-qPCR, and statistical significance was determined with GraphPad Prism 8 software ( p  < 0.05). Results The absolute ethanol extract of E. gracilistylus , particularly from the fruit, achieved nearly 90% inhibition in the HT-29 cell line at 250 µg/ml. The ethyl acetate fraction demonstrated the highest cancer stem cell inhibition at 80%, while the butanol fraction significantly induced apoptosis, increasing the rate from 11.9–19.2%. Flow cytometry confirmed a marked reduction in ALDH 1-A1 expression and a concentration-dependent decrease in Nanog and Oct4 levels after treatment with the ethyl acetate fraction. Conclusions The absolute ethanol extract of E. gracilistylus demonstrated potent anticancer effects, especially against HT-29 cells, and significant CSC inhibition. These findings highlight its therapeutic potential in targeting colorectal cancer.