Phenolic-Rich Extracts from Artichoke By-Products Promote Apoptosis in Human Colorectal Cancer Cell Lines

Background: Apoptosis is a fundamental process for maintaining tissue homeostasis, and its dysregulation is closely linked to the development of numerous diseases, including colorectal cancer. In recent years, dietary polyphenols have gained interest due to their antioxidant, pro-apoptotic, and chemopreventive properties. Artichoke (Cynara scolymus L.) by-products are rich source of hydroxycinnamic acids and flavonoids, making them promising source of bioactive compounds. Methods: In this study we evaluated the cytotoxic and pro-apoptotic activity of four aqueous extracts obtained from artichoke bract by-products, including one commercial hybrid (CAPB) and three local Apulian varieties (BriB, VaMB, LMTB), in human colorectal adenocarcinoma cell lines (Caco-2 and HT29). The extracts were characterized according to their total polyphenol content and phenolic profile. Results: The selected artichoke by-product extracts exhibited significant cytotoxic effects both in a concentration- and time-dependent manner, with concentrations ≥ 2 mg/mL significantly reducing cell viability and nearly abolishing it at 4 mg/mL after 48 h. Moreover, treatment with the extracts modulated the expression of apoptosis-related proteins, characterized by an increase in pro-apoptotic markers (Bax, caspase-9, caspase-3) and a decrease in the anti-apoptotic protein Bcl-2, suggesting activation of the mitochondrial apoptotic pathway. In particular, the BriB extract was able to induce an apoptosis rate higher than 80% in Caco-2 cells and achieved comparable rates in HT29 cells at concentrations of 2–3 mg/mL. Conclusions: Overall, these findings demonstrate that artichoke by-product extracts exert significant pro-apoptotic effects in colorectal cancer cells and highlight their potential as sustainable sources of bioactive compounds for nutraceutical or adjuvant anticancer applications.