Innovative Photoprotection Strategy: Development of 2-(Benzoxazol-2-Yl)[(2-Hydroxynaphthyl)Diazenyl] Phenol Derivatives for Comprehensive Absorption of UVB, UVA, and Blue Light

Overexposure to blue light due to the excessive use of electronic devices has been implicated in premature skin aging and eye damage, among other injuries to health. This study aimed to synthesize two azo derivatives of the 2-(amino-2′-hydroxyphenyl) benzoxazole and explore their potential as UV and blue light filters, proposing a new spectral profile. The synthesis of the heterocyclic compounds involved condensation reactions and diazotation. The derivatives 2-(benzoxazol-2-yl)-5-[(2-hydroxynaphthyl)diazenyl]phenol and 2-(benzoxazol-2-yl)-4-[(2-hydroxynaphthyl)diazenyl]phenol were synthesized with a yield greater than 70%. Solubility was evaluated in seven different solvents. The maximum absorption wavelengths (λ_max) were determined using UV–Vis scanning spectrophotometry in the range of 200–600 nm. Photostability was assessed using a solar simulator and the Sun protection factor (SPF) was determined using in vitro methodology. Cytotoxicity was evaluated using the MTT assay in V79 cells. These compounds were able to absorb UVA, UVB, and blue light, with λ_max ranging from 300 to 500 nm and demonstrated photostability after 3 h of exposure to solar simulator with an SPF higher than 45. The compounds exhibited solubility in all lipophilic solvents tested. Regarding cytotoxicity, IC50 values were comparable to other filters. These findings indicate that both compounds hold promise as potential organic filters.