Phytochemical profiling and antioxidant activity of Yuwolcho chili leaves (Capsicum annuum L.) under different light regimes, with policosanol analysis highlighting functional food potential

Chili leaves (Capsicum annuum L.) are traditionally and frequently consumed in Korea, yet their functional value and optimal cultivation conditions remain insufficiently characterized. This study examined the phytochemical profiles including phenolics, flavonoids, fatty acids, and policosanols, and antioxidant capacity and phytochemical alteration of Yuwolcho chili leaves grown under two cultivation environments: a smart farm (SF) with controlled LED lighting and a glasshouse (GH) natural sunlight reliant. Fatty acid methyl ester analysis revealed higher total fatty acid content (44 µg mg−1) in GH-grown leaves, primarily driven by elevated levels of C16:0, C18:2, and C18:3. Conversely, SF cultivation significantly enhanced total phenolic (12.5%) and flavonoid (64%) contents, which corresponded with markedly increased DPPH and ABTS radical scavenging activities. HPLC-ESI-QTOF-MS profiling identified 35 bioactive compounds, including phenolic acids, flavonoid O- and C-glycosides, and uncommon glycosylated derivatives. Quantitative analysis showed that luteolin-7-(2″-apiosylglucoside) and luteolin-O-glucoside (threefold), chlorogenic acid isomers (1.7 fold), and chrysoeriol-7-O-apiosylglucoside (twofold) were substantially enriched under SF conditions, collectively contributing to the enhanced antioxidant capacity compared to GH cultivation. Additionally, GC–MS analysis of the wax layer detected abundant policosanols (21 µg mg−1 fresh weight), predominantly octacosanol and triacontanol, supporting their potential nutraceutical relevance. Overall, these findings demonstrate that cultivation environment strongly influences the metabolic composition of chili leaves, with SF conditions maximizing antioxidant-related phytochemicals and GH conditions enhancing fatty acid accumulation. This work provides a scientific foundation for cultivation strategies aimed at functional food applications and highlights chili leaves as a promising high-value resource rather than agricultural by-product wastes.