Antioxidant Activity of Bioactive Peptides Derived from Ulva prolifera in HaCaT Cells and Zebrafish.

Ulva prolifera (U. prolifera), a large green alga widely distributed along coastlines worldwide, can trigger marine ecological issues such as "green tides" when over-proliferating. Nevertheless, it is abundant in various nutrients and bioactive compounds, making the utilization of this alga an urgent task. In this study, an antioxidant peptide fraction (UCP‑1) was isolated and purified from U. prolifera. LC‑MS/MS analysis indicated that the peptide composition and molecular weight distribution of UCP‑1 possess typical characteristics of antioxidant peptides. In vitro experiments demonstrated that UCP‑1 at a concentration of 1 mg mL⁻¹ exhibited a DPPH radical scavenging capacity of 38.86 ± 2.7%, indicating antioxidant activity. In human immortalized keratinocytes (HaCaT) and zebrafish models, UCP-1 pretreatment reduced hydrogen peroxide (H₂O₂)-induced reactive oxygen species (ROS) and malondialdehyde (MDA) levels while increasing superoxide dismutase (SOD) activity. In zebrafish, UCP-1 also enhanced catalase (CAT) and glutathione peroxidase (GSH-Px) activities. In addition, incorporation of UCP‑1 into lotions and creams in skin trials improved skin hydration and elasticity and reduced erythema. Overall, the peptide UCP‑1 derived from U. prolifera exerts antioxidant activity and may serve as a natural antioxidant ingredient in cosmetic formulations, thereby providing an alternative approach for the high-value utilization of U. prolifera resources.