Anthocyanin-loaded chitosan-alginate nanoparticles from red dragon fruit pulp for targeted therapy against HCT116 colon cancer cells.

This research focuses on the extraction, purification, characterization, and bioactivity evaluation of anthocyanins (ACNs) derived from red dragon fruit pulp, followed by their encapsulation into chitosan-alginate nanoparticles (CH@ALG-ACN NPs). The crude ACN extract initially contained 56.43 mg/g, which increased to 124.91 mg/g following ethanol precipitation. Further purification using Sephadex LH-20 column chromatography enhanced the ACN content to 227.74 mg/g in the 80% ethanol fraction. Structural characterization using FTIR, HPLC, and GC-MS confirmed the presence of key anthocyanin compounds. The synthesized CH, CH-ALG, and CH@ALG-ACN nanoparticles exhibited distinct physicochemical characteristics, as determined by UV-Vis, FTIR, DLS, zeta potential, XRD, and HR-TEM analyses. Encapsulation efficiency varied between 58.2% and 85.1%. In vitro release studies demonstrated a sustained ACN release pattern influenced by pH over a 24-h period. Antioxidant evaluations, including DPPH, FRAP, HRSA, and RPA assays, demonstrated that CH@ALG-ACN NPs exhibited superior antioxidant activity compared to free ACNs. Cytotoxicity assessments on HCT116 colorectal cancer cells using the MTT assay indicated a dose-dependent inhibition, with CH@ALG-ACN NPs showing a lower IC50 value (40.25 μg/mL) compared to free ACNs (69.31 μg/mL). AO/EtBr staining and cell cycle analysis further confirmed increased apoptotic activity and alterations in cell cycle progression in response to CH@ALG-ACN NP treatment.