Background Takifugu bimaculatus is one of the main species of cultured puffer fish in Fujian Province. The significant increase in its production in recent years has led to an increasingly urgent need for high-value utilization of processing by-products such as its skin.

Objective Long-term exposure to ultraviolet B (UVB) radiation leads to skin inflammation and a reduction in dermal collagen, among other photodamage phenomena. This study utilized UVB-irradiated mouse fibroblasts as a model for photodamage to investigate the reparative effects of low molecular weight collagen peptides derived from T. bimaculatus fish skin (TBCP-L) on UVB-exposed L929 cells.

Methods The study first verified the safety of TBCP through in vitro models. Subsequently, TBCP-L with a molecular weight less than 3 kD was obtained through ultrafiltration. Cell viability assays were conducted to evaluate the preventive and reparative effects of TBCP-L on UVB-irradiated L929 cells. Real-time quantitative polymerase chain reaction (qPCR) was used to detect the messenger ribonucleic acid (mRNA) expression levels of inflammatory cytokines and matrix metalloproteinases (MMPs) in UVB-exposed L929 cells. The wound healing effect of TBCP-L was studied through a cell scratch assay.

Results Episkin^TM 3D models and bovine corneal experiments indicated that 1.5 g/mL TBCP solution was non-irritating to skin and eyes. The molecular weight distribution results indicated that the weight-average molecular weight of TBCP-L was 2352 Da, with 80.2% of the components having a molecular weight below 2200 Da. A 2 mg/mL TBCP-L concentration was non-toxic to L929 cells and did not prevent UVB radiation damage but exhibited significant reparative activity. qPCR results indicated that TBCP-L could significantly inhibit the upregulated expression of inflammatory cytokines such as interleukin-1β, interleukin-6, tumor necrosis factor-α and cyclooxygenase-2 and MMP2, MMP3, and MMP9 in L929 cells following UVB stimulation. Additionally, incubation with 500 μg/mL TBCP-L for 96 h significantly accelerated the scratch repair rate of L929 cells, with a migration rate reaching 37.8%±3.3%.

Conclusion In conclusion, TBCP-L may accelerate the repair of UVB-irradiated L929 cells by inhibiting inflammatory responses and collagen loss, and it is non-irritating to the skin and eyes. It is a potential candidate for anti-aging and post-sun exposure repair cosmetic ingredients.

Significance  This study aims to investigate the potential of TBCP-L as a cosmetic ingredient for mitigating photoaging and post-sun exposure repair, providing robust theoretical support for its efficacy. Additionally, it holds significant practical implications for the high-value utilization of puffer fish resources and the sustainable development of the industry.