Assessment of phototoxicity potential of botanicals as cosmetic ingredients using the in vitro 3T3 neutral red uptake phototoxicity test.

Cosmetics and personal care products are frequently formulated with botanical ingredients due to their beneficial properties, the nature of their composition, and consumers' interest for products with more natural or organic profiles. Compounds that absorb light significantly and are in contact with the skin have potential to become phototoxic upon exposure to sunlight. Here we demonstrate that an in vitro test methodology, the 3T3 Neutral Red Uptake Phototoxicity Test (3T3 NRU PT), is an effective screening tool in evaluation of botanical ingredients that absorb light in the Ultraviolet/Visible (UV/Vis) range. Thirty-eight prospective botanical ingredients were evaluated in the 3T3 NRU PT assay. Five botanicals were identified to have phototoxicity potential, and were eliminated from consideration for use. Thirty three botanicals were identified to have no phototoxicity potential in the 3T3 NRU PT; and a subset of six were further evaluated in a clinical confirmatory test that corroborated the data obtained using the in vitro test. Our results support this in vitro test method as a reliable, high throughput model in evaluating a large subset of compounds to efficiently identify those that pose a potential risk and to ensure that marketed cosmetic products do not contain ingredients with phototoxicity potential.