Formulation and evaluation of ulvan-functionalized cumin oil nanoemulsions for antioxidant, anti-photoaging, and anti-melanogenesis activities in skin cells

Growing interest in natural skincare solutions has spotlighted bioactive substances like ulvan and cumin essential oil, valued for their roles in combating oxidative stress and inflammation. In this study, cumin oil-based nanoemulsions with and without ulvan extract (CC@NE and UP-CC@NE) were developed using ultrasonication and evaluated for their potential in protecting against oxidative stress, photoaging, and melanogenesis. The formulations exhibited droplet sizes below 100 nm, low polydispersity indices (PDI < 0.2), and negative zeta potentials (- 4.67 to - 11.90 mV), indicating good stability. In vitro assays demonstrated concentration-dependent antioxidant activity, as well as inhibition of tyrosinase, collagenase, and elastase. Both nanoemulsions maintained over 70% cell viability in L929 fibroblasts at 0.25% concentration. In HaCaT keratinocytes, 0.25% nanoemulsions significantly suppressed the production of reactive oxygen species (ROS) triggered by hydrogen peroxide (H₂O₂), while in B16F10 melanoma cells, concentrations above 0.025% reduced cell viability and inhibited melanogenesis, with notable effects observed at 0.01-0.025%. Under ultraviolet A (UVA) irradiation, 0.1% nanoemulsions improved cell viability and reduced ROS levels, indicating anti-photoaging effects. Notably, the ulvan extract-containing formulation (UP-CC@NE) consistently outperformed the formulation without ulvan extract, which may suggest potential synergistic effects. These findings highlight the potential of ulvan-functionalized cumin oil nanoemulsions as effective, natural agents for skin protection.