Bioactivity-Guided Fractionation and Mechanistic Insights into Aristolochia ringens Root Extract-Induced G(1) Phase Arrest and Mitochondria-Mediated Apoptosis in Human Colon Adenocarcinoma Cells.

Background/Objectives: Aristolochia ringens, a medicinal plant widely used in traditional medicine, has shown potential therapeutic applications. This study aimed to investigate the anticancer mechanism of action of its crude extract against human colorectal adenocarcinoma cells (Caco-2 and HT-29). Methods: Cell viability was assessed using the MTT assay to determine IC(50) values. Immunofluorescence microscopy was used to examine nuclear morphology and microtubule integrity. Flow cytometry with PI staining was used for cell cycle analysis and Annexin V-FITC/PI staining for apoptosis detection. Mitochondrial membrane potential was evaluated using JC-1 dye. Bioactivity-guided fractionation was performed via HPLC, and GC-MS was used to profile active constituents. Results: The extract exhibited dose-dependent cytotoxicity with IC(50) values below 30 µg/mL in colon adenocarcinoma cell lines. Treated Caco-2 cells showed nuclear shrinkage and disrupted microtubules. PI-based flow cytometry revealed G(1) phase arrest, and Annexin V-FITC/PI staining indicated enhanced late apoptosis. JC-1 staining demonstrated mitochondrial depolarization. HPLC fractionation identified fractions 2 and 3 as active, and preliminary GC-MS analysis tentatively annotated the presence of alkaloids, sesquiterpenes/diterpenes, and steroidal compounds. Conclusions: A. ringens exerts anticancer effects through a mitochondria-mediated apoptotic pathway, involving G(1) checkpoint arrest and cytoskeletal disruption. These findings provide the first integrated cellular and mechanistic evidence of its anticancer potential in colorectal cancer, supporting its promise as a source of novel therapeutic lead compounds.