Comparative Evaluation of the Antiproliferative and Pro-Apoptotic Activities of Origanum majorana, Salvia officinalis and Ribes nigrum Extracts in Human Colorectal Cancer and Normal Intestinal Cells

Colorectal cancer remains a significant global health challenge, highlighting the need for targeted therapeutic strategies. Plant-derived bioactive compounds are of interest due to their antiproliferative and pro-apoptotic properties. This study investigated the total phenolic and flavonoid contents, antioxidant activity and anticancer potential of Origanum majorana, Salvia officinalis, and Ribes nigrum extracts using normal human intestinal epithelial cells (HIEC-6) and human colorectal carcinoma cells (HCT-116). Cell viability was assessed using the MTT assay, while apoptosis and necrosis were evaluated by Annexin V-FITC/propidium iodide staining followed by flow cytometry. Ribes nigrum exhibited the highest phenolic content and antioxidant activity, whereas Origanum majorana contained the highest flavonoid concentration. All tested extracts reduced HCT-116 cell viability in a concentration-dependent manner while maintaining high viability in HIEC-6 cells (>93%). At the highest tested concentration, R. nigrum and S. officinalis reduced HCT-116 viability to approximately 13–14% and 16–18%, respectively, whereas O. majorana reduced viability to 18–19%. Annexin V/PI analysis demonstrated marked increases in late apoptotic and necrotic populations in HCT-116 cells, confirming selective pro-apoptotic activity. Overall, these extracts demonstrated selective antiproliferative and pro-apoptotic activities while exerting minimal toxicity toward normal intestinal epithelial cells. These findings support the potential of extracts as complementary sources of bioactive compounds for colorectal cancer prevention and therapy.