Apoptosis- inducing and cytotoxicity potential of ethanolic flower extract Combretum indicum against human retinoblastoma (Y79) cells validated by in vitro and in silico docking studies

This study investigates the phytochemical composition, antioxidant potential, molecular interactions, and anticancer activity of the ethanolic flower extract derived from Combretum indicum. Qualitative analysis showed a rich presence of alkaloids, flavonoids, terpenoids, phenolic compounds, and quinones, alongside moderate amounts of saponins, cardiac glycosides, and steroids. The extract demonstrated concentration-dependent antioxidant activity in both the Ferric Reducing Antioxidant Power and phosphomolybdenum assays, showing IC₅₀ values of 150 and 106.78 µg/mL, respectively. Major phytoconstituents, such as α-amyrin, 6-cyanoquinoline, supraene, trans-linalool, n-hexadecanoic acid, and hentriacontane, performed molecular docking studies with retinoblastoma protein (Rb, PDB ID: 3N5U). α-Amyrin exhibited the highest binding affinity (–8.6 kcal/mol), exceeding that of the standard drug methotrexate, indicating considerable inhibitory potential. In vitro cytotoxicity assays carried out on Y79 retinoblastoma cells demonstrated a dose-dependent decrease in cell viability (IC₅₀ = 118.07 µg/mL), along with morphological alterations indicative of apoptosis. AO/EB dual staining, Annexin V/PI flow cytometry, and DNA fragmentation assays validated that apoptosis is the primary mechanism of cell death. The findings suggest that C. indicum flower extract, especially α-amyrin, has strong antioxidant and anticancer effects, emphasizing its potential as a natural treatment option for retinoblastoma.