Comparative metabolomic profiling of underutilized pumpkin (Cucurbita moschata) leaves and stems: Tissue-specific phytochemicals and bioactive properties.

Pumpkin (Cucurbita moschata Duchesne) leaves and stems are underutilized plant resources with potential functional value. The leaf extract exhibited higher total phenolic content (92.32 ± 0.34 μg GAE/mg) and total flavonoid content (15.90 ± 0.29 μg QE/mg) than the stem extract (11.18 ± 0.37 μg GAE/mg and 2.70 ± 0.05 μg QE/mg, respectively), corresponding to approximately 8.2- and 5.9-fold differences, respectively. Consistently, the leaf extract showed lower IC50 values than the stem extract in both the ABTS assay (0.66 vs. 3.96 mg/mL) and DPPH assay (0.95 vs. 9.74 mg/mL), corresponding to approximately 6.0- and 10.3-fold differences, respectively. In lipopolysaccharide-stimulated RAW 264.7 macrophages, the leaf extract significantly inhibited nitric oxide production and pro-inflammatory cytokine levels (p < 0.001), whereas the stem extract showed limited inhibitory effects on nitric oxide production. Non-targeted metabolomic analysis combined with feature-based molecular networking revealed distinct metabolomic profiles between leaves and stems (false discovery rate < 0.05). Quercetin glycosides and phenylpropanoid derivatives were more abundant in leaves, while kaempferol glycosides and methylated flavonols were relatively higher in stems. These results demonstrate tissue-dependent differences in the bioactivity and metabolomic profiles of pumpkin leaves and stems, providing preliminary information to guide the selection of plant parts for further investigation of their potential nutraceutical applications.