Bioactivity-Guided Fractionation of the Bidah Pomegranate Landrace Identifies a Bioactive Fraction Inducing Mitochondria-Associated Apoptotic Responses in Colorectal Cancer Cells

Abstract

Pomegranate (Punica granatum L.) has attracted considerable attention for its anticancer potential; however, mechanistic studies employing bioactivity-guided fractions from geographically distinct landraces remain limited. Building on our previous report on the bioactivity and phytochemical profile of the Bidah pomegranate landrace, the present study applied bioactivity-guided fractionation to enrich biologically active constituents and investigate mitochondria-associated cellular responses in colorectal cancer cells (Caco-2 cells). A semi-polar fraction from Bidah pomegranate crude extract (B6) was evaluated for its antioxidant activity, cell viability, cell death morphology, mitochondrial membrane potential, transcriptional modulation of key regulatory genes, and phytochemical composition. High-performance liquid chromatography (HPLC) profiling of B6 revealed a chromatographic fingerprint with seven detectable peaks, including two major peaks at retention times of 7.577 and 8.602 min, together accounting for approximately 66% of the total chromatographic area, indicating the enrichment of major constituents. Consistent with this enrichment, the fraction exhibited potent DPPH radical scavenging activity at a microgram-range IC50, suggesting the presence of redox-active phytochemicals. In cell-based assays, the fraction induced a dose-dependent reduction in metabolic viability, while acridine orange/propidium iodide (AO/PI) staining of Caco-2 cells revealed delayed, regulated cell death. JC-1 staining demonstrated a pronounced loss of mitochondrial membrane potential, consistent with early mitochondrial dysfunction. Gene expression analysis further revealed modulation of pro- and anti-apoptotic genes, alongside cell-cycle-associated and oxidative stress/inflammatory markers. Gas chromatography–mass spectrometry (GC–MS) profiling identified polyacetylenes, sterol derivatives, fatty acid esters, and terpenoids, providing chemical context for the observed mitochondrial perturbation. Collectively, the findings support a mitochondria-centered, regulated cell death response driven by a multi-component phytochemical matrix. This study advances mechanistic insight beyond crude extract analysis and highlights the sustainable biomedical value of the Bidah pomegranate landrace as an underutilized regional resource.