Chemical Composition and Biological Activity of Phenolic Compounds and Carotenoids Extracted from Yellow-Purple Polignano Carrots

Anthocyanin-rich fruits and vegetables are widely recognized for their antioxidant and health-promoting properties. This study investigated the chemical composition and in vitro biological activity of extracts from the yellow-purple Polignano carrot, a traditional multicolored landrace from Southern Italy. Among the yellow, orange, and purple variants, the purple carrots exhibited an approximately tenfold higher antioxidant capacity (45 ± 0.23 mg Trolox g−1 FW) and were therefore selected for further analysis. Fifteen phenolic compounds, three carotenoids, and twenty-nine lipid molecular species were identified. The (poly)phenol extract from purple Polignano carrots induced a dose-dependent hormetic response in the range 50–500 μg/mL in HT-29 and U2OS cancer cells, stimulating viability at low concentrations and slightly reducing it at higher doses. In contrast, a carotenoid-enriched nanoemulsion triggered marked cytotoxic and pro-apoptotic effects in U2OS cells at 50 μg/mL concentration, as evidenced by increased caspase-3 activity, while a control pumpkin-derived nanoemulsion was inactive. These results highlight the distinct biological activities of (poly)phenols and carotenoids and underscore the importance of nanoformulation strategies in enhancing carotenoid bioactivity, supporting their potential application in functional foods and nutraceutical development.