Hydrophobic Rose Bengal Derivatives Exhibit Submicromolar-to-Subnanomolar Activity against Enveloped Viruses

Rose Bengal (RB) is an anionic xanthene dye with multiple useful biological features, including photosensitization properties. RB was studied extensively as a photosensitizer, mostly for antibacterial and antitumor photodynamic therapy (PDT). The application of RB to virus inactivation is rather understudied, and no RB derivatives have been developed as antivirals. In this work, we used a synthetic approach based on a successful design of photosensitizing antivirals to produce RB derivatives for virus photoinactivation. A series of n-alkyl-substituted RB derivatives was synthesized and evaluated as antiviral photosensitizers. The compounds exhibited similar (1)O(2) generation rate and efficiency, but drastically different activities against SARS-CoV-2, CHIKV, and HIV; with comparable cytotoxicity for different cell lines. Submicromolar-to-subnanomolar activities and high selectivity indices were detected for compounds with C(4-6) alkyl (SARS-CoV-2) and C(6-8) alkyl (CHIKV) chains. Spectrophotometric assessment demonstrates low aqueous solubility for C(8-10) congeners and a significant aggregation tendency for the C(12) derivative, possibly influencing its antiviral efficacy. Initial evaluation of the synthesized compounds makes them promising for further study as viral inactivators for vaccine preparations.