Optimization and Characterization of Serum of Red Onion Skin Extract and Antioxidant Activity

Red onion (Allium cepa L.) skin is enriched with flavonoids, steroids, and phenolic compounds, which possess the potential to promote hair growth. The present investigation sought to optimize gelling agent concentrations within hair serum formulations incorporating red onion peel extract (Allium cepa L.) for its antioxidant properties. Formula optimization was executed employing the Regular Two-Level Factorial Design methodology utilizing Design Expert® 13 software. Two independent variables were examined: carbomer 940 concentration ranging from 0.1–0.3% and sodium alginate concentration ranging from 0.5–1%. Through factorial analysis of physical properties, formula 2 emerged as optimal, containing carbomer 940 at 0.3% and sodium alginate at 1%. The resultant formulation demonstrated the following physicochemical characteristics: pH of 6.14±0.01, viscosity of 854.35±12.87 cP, spreadability of 7.26±0.70 cm, adhesiveness of 8.02±0.19 cm, and additional adhesion metrics of 8.69±0.27 cm, 4.17±0.23 s, and 3.35±0.26 s. Accelerated stability assessment via cycling protocols revealed preservation of organoleptic integrity, absence of phase separation or syneresis, and constancy in pH and viscosity parameters. The optimal red onion peel extract serum formulation demonstrated an IC50 value of 84.00 ppm, reflecting substantial antioxidant capacity and considerable promise for further pharmaceutical development as an antioxidant agent.