“One-pot” green synthesis of sea cucumber peptide/pomegranate peel derivative nanoparticles with good scavenging of reactive oxygen species and alleviating fat accumulation

Abstract The common practice of discarding pomegranate peels, which constitute 20%–30% of the fruit's weight, as agricultural waste in landfills leads to significant resource wastage and exacerbates environmental challenges. Contrary to being worthless, a growing body of evidence confirms that pomegranate peels are a valuable repository of bioactive compounds, notably pomegranate peel polyphenols (PPP). In this study, nanoparticles were synthesized directly from a crude pomegranate peel extract to increase the utilization of PPP. The preparation involved mixing fresh pomegranate peel solution with vanillin and sea cucumber peptide (SCP), followed by collection of the resulting precipitate to obtain PPP-based nanoparticles (PPP–SCP NPs). Notably, the green synthesis of PPP–SCP NPs eliminates the need for organic solvents and toxic crosslinkers, thereby improving their biocompatibility and potential scalability. The optimized PPP–SCP NPs exhibited a small hydrodynamic diameter around 268 nm and a PDI of 0.299, suggesting favorable colloidal stability. The recovery rate of polyphenols in PPP–SCP NPs was about 30%. The main types of polyphenols were flavonoids (47.52%), followed by phenolic acids (33.07%) and tannins (10.89%). In vitro, PPP–SCP 2 NPs effectively alleviated H₂O₂-induced mitochondrial dysfunction in RAW 264.7 cells and reduced oleic acid-induced lipid accumulation in HepG2 cells. While the antioxidant and lipid-modulating activities were exclusively evaluated in vitro, this study demonstrates the conversion of pericarp waste into functional nanoparticles, thereby offering a sustainable circular economy concept that merits further in vivo validation.