Safety Assessment of Ethanolic Extract of Padina gymnospora as a Cosmetic Ingredient

Purpose: In a previous study, we identified the skin-whitening effect of the ethanolic extract of Padina gymnospora. The present study was performed to confirm the safety of the extract in animal replacement tests.Methods: To evaluate the safety of the extract of Padina gymnospora, the photosensitivity test (Harber test), in vitro 3T3 neutral red uptake (3T3 NRU) phototoxicity test, local lymph node assay (5-bromo-2'-deoxyuridine enzyme-linked immunosorbent assay), acute oral toxicity test, and reconstructed human epidermis (RHE) test were used. All experiments followed the guidelines of the Korean Ministry of Food and Drug Safety and were conducted by a GLP-certified organization (Chemon Inc.).Results: The extract of Padina gymnospora was not photosensitive: 0% photosensitization was detected (I grade: very weak). In the 3T3 NRU phototoxicity test, the relative viability of the extract-treated cells was higher than the guideline level; thus, the extract was classified as non-phototoxic. Treatment with the extract did not trigger skin irritation in the RHE test model and did not cause skin sensitization in the local lymph node assay. Finally, oral administration of the extract to rats indicated that it was not a harmful material as the LD50 was estimated at >2,000 mg/kg.Conclusion: The ethanolic extract of Padina gymnospora was demonstrated to be safe when applied to the skin. Taken together with our previous study of its efficacy, we conclude that this extract has the potential for use as a cosmetic ingredient.