Phytochemical Profiling and Anti-Inflammatory Effects of Aerial and Underground Parts of Apium graveolens var. rapaceum (Celeriac): Potential Health Benefits of Discarded Aerial Parts

Abstract

Apium graveolens var. rapaceum (celeriac), a root vegetable cultivated as a medicinal plant since ancient times, has gained attention due to its nutritional and health benefits. The aerial parts of celeriac (APC) are rich in compounds such as apigenin, known for its potent anti-inflammatory properties. However, APC is often discarded due to its tough texture and bitter taste. To assess the health benefits and explore the potential of both the APC and underground parts of celeriac (UPC) as functional food ingredients, their phytochemical profiles and anti-inflammatory effects were evaluated. In particular, this study aimed to investigate the feasibility of utilizing the often-discarded APC as a functional food by thoroughly analyzing the composition of the entire celeriac plant. Phytochemical analysis of APC and UPC revealed 31 compounds, including 9 hydroxycinnamic acids, 2 hydroxycoumarins, 1 flavonol, 8 flavones, 8 furanocoumarins, and 3 phthalides. APC contained higher levels of compounds providing anti-inflammatory effects and health benefits than UPC. When evaluating their anti-inflammatory effects in LPS-induced RAW264.7 macrophages, ethanolic extracts of APC (APCE) and UPC (UPCE) reduced NO and PGE₂ production in a concentration-dependent manner (p < 0.05), decreased mRNA expression levels of iNOS and COX-2 (p < 0.05), and suppressed mRNA levels of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β). Notably, APCE demonstrated strong anti-inflammatory effects at higher concentrations (0.5 mg/mL, p < 0.05). This study confirms the potential of currently discarded APC as functional food ingredients and pharmacological substances, suggesting they could offer health benefits.