Biological activity of P2Et extract from Caesalpinia spinosa on colorectal cancer cell lines

Colorectal cancer is the third most diagnosed malignancy and the second leading cause of cancer-related mortality worldwide, with approximately 1.9 million new cases and 0.9 million deaths reported in 2022. Although 5-fluorouracil is widely used in treatment, its clinical benefit is limited by systemic toxicity, low selectivity, and adverse effects that negatively impact patients’ quality of life. In recent years, phytochemicals have gained increasing interest due to their ability to modulate multiple pathways involved in tumor progression. In this context, this study aimed to evaluate the antitumor potential of P2Et, a standardized extract derived from Caesalpinia spinosa and obtained under good laboratory practices, in colorectal cancer cell lines. The selective biological activity of P2Et was evaluated in human (SW480 and SW620) and murine (CT26) colorectal adenocarcinoma cell lines using a colorimetric viability assay. Cell viability data were normalized to untreated controls and analyzed by nonlinear regression to estimate half-maximal inhibitory concentration values. The selectivity index was calculated using a non-malignant cell line. Antiproliferative activity and intracellular reactive oxygen species levels were assessed using fluorescence-based assays and analyzed using two-way analysis of variance followed by Dunnett’s post hoc test. Apoptosis was evaluated by caspase-3/7 activation and nuclear staining using fluorescence microscopy. Mitochondrial permeability transition pore opening was examined using a fluorescence-based assay and analyzed by microscopy. A p value ≤ 0.05 was considered statistically significant. P2Et showed comparable responses in SW480 and SW620 cells, with no significant cytotoxicity under the conditions tested. In CT26 cells, P2Et reduced cell viability and was associated with increased ROS production and caspase-3/7 activation at 48 h. No changes in mitochondrial permeability transition pore opening were detected. These findings provide preliminary evidence of cellular responses to P2Et treatment; however, further studies are required to determine their relationship with P2Et-induced cell death and to elucidate the underlying mechanisms. P2Et exhibits selective biological activity in murine colorectal cancer cells, associated with oxidative stress and caspase activation. These findings support the potential of phytochemicals as alternative or adjuvant therapeutic strategies and highlight the need for further studies to better understand their mechanisms of action.