Proximate Composition, Phytochemical Profile, and Antioxidant Activity of Flamboyant (Delonix regia) Seed Fractions

Delonix regia seeds are an underutilized legume resource containing protein and galactomannan-rich polysaccharides. This study evaluated the proximate composition, some phytochemicals, and in vitro antioxidant capacity of flamboyant seeds (FWS), germ (FG), defatted germ (DFG), and native mucilage (FNM). Protein was concentrated in FG and DFG (59.98% and 75.51%, respectively); FNM had a high nitrogen-free extract content (95.21%). DFG showed the highest total phenolic and flavonoid contents (231.08 mg GAE/g sample and 207.62 mg CE/g sample, respectively). Anthocyanins were low, with the highest value in FWS (0.31 mg C3G eq/g sample), followed by DFG (0.25 mg C3G eq/g sample) and FG (0.10 mg C3G eq/g sample), and not detected in FNM. DFG also exhibited the highest in vitro antioxidant capacity by DPPH, ABTS, and FRAP assays (71.06, 34.47, and 143.34 µmol TE/g sample, respectively). Strong positive correlations were observed between total phenolic content and the three antioxidant assays, and between total flavonoid content and DPPH and ABTS. These results demonstrate compositional differences among D. regia seed fractions, indicating that FG and DFG are protein-rich fractions, whereas FNM is polysaccharide-rich. Further studies on compound identification, bioavailability, toxicity, and food-system performance are required before proposing their use as functional food ingredients.