Comparative Evaluation of the Antioxidant and Immunomodulatory Activities of Carrot (Daucus carota L.) Aerial Parts...

Carrot (Daucus carota L.) is a widely consumed root vegetable, yet its aerial parts, including leaves and stems, are typically discarded as agricultural by-products, despite their potential biological value. This study comparatively evaluated the antioxidant and immunomodulatory properties of carrot aerial and root parts extracted using hot water or 50% ethanol. Four extracts were prepared: aerial part hot-water (AP-W), aerial part ethanol (AP-E), underground part hot-water (UP-W), and underground part ethanol (UP-E). The total phenolic content (TPC, expressed as gallic acid equivalents; GAE) and total flavonoid content (TFC, expressed as quercetin equivalents; QE) were quantified using the Folin-Ciocalteu and aluminum nitrate colorimetric methods, respectively. Antioxidant capacities were determined by ABTS and DPPH radical scavenging assays, cytotoxicity was assessed in RAW 264.7 macrophages via the MTT assay, nitric oxide (NO) levels were measured using the Griess reaction, and cytokine (IL-6, TNF-α) concentrations were analyzed by ELISA. Among the extracts, AP-E exhibited the highest TPC (28.3 ± 0.3 µg GAE/mg extract) and TFC (18.2 ± 2.3 µg QE/mg extract), corresponding to the strongest ABTS (92.3 ± 2.5%) and DPPH (72.4 ± 7.3%) radical scavenging activities. None of the extracts demonstrated cytotoxicity below 400 µg/mL. Under basal conditions, AP-W and UP-W significantly enhanced NO production (9.5 ± 1.3 µM and 7.7 ± 1.2 µM, respectively), while co-treatment with LPS markedly reduced NO levels in AS-E (2.3 ± 0.2 µM). Consistently, AP-W and UP-W elevated cytokine secretion (IL-6: 3462.1 ± 349.7 pg/mL and 1749.4 ± 55.4 pg/mL; TNF-α: 15,245.2 ± 771.0 pg/mL and 14,719.1 ± 329.8 pg/mL), whereas AP-E (400 µg/mL) significantly suppressed IL-6 (3938.6 ± 268.7 pg/mL) and TNF-α (11,869.0 ± 721.1 pg/mL) under LPS-stimulated conditions. Collectively, these results indicate that hot-water extracts of carrot parts exert immunostimulatory activity, whereas ethanol extracts possess potent anti-inflammatory potential. The aerial parts of carrots, often regarded as waste biomass, exhibit comparable or superior bioactivities to the roots, underscoring their potential utility as promising functional food ingredients.