Enhanced photostability and biocompatibility of sunscreen formulation of 2-phenylbenzimidazole-5-sulfonic acid with methyl-beta-cyclodextrin

Ensuring the photostability of sunscreen lotions is crucial for their effectiveness and safety when exposed to sunlight. Photostability refers to the ability of a substance to remain stable and undergo minimal chemical degradation or photochemical reactions upon exposure to ultraviolet (UV) radiation, especially from sunlight. In this study, we focused on 2-phenylbenzimidazole-5-sulfonic acid (PBS), one of the leading sunscreen agents, and aimed to form inclusion complexes (IC) with methyl-beta-cyclodextrin (MCD). Through phase solubility measurements, we determined the stoichiometry of the IC to be 1:1, with a binding constant of 155.4 M-1. Proton Nuclear Magnetic Resonance (1H NMR) and ROESY analysis provided evidence that the benzimidazole part of PBS is successfully included in the cavity of MCD. Quantum mechanical calculations using the B3LYP/6-31G(D, P) method in the Gaussian 16 package further supported the formation of the IC by providing energy data. Notably, the photostability of the IC is maintained for up to four hours of UV exposure, showing no significant structural changes in PBS. Moreover, we conducted biocompatibility tests, and the results are encouraging for the superior activity, and suggest the potential of the IC for promoting its cosmetic application as a UVB sunscreen.

Automated summary

This study focuses on improving the photostability of 2-phenylbenzimidazole-5-sulfonic acid (PBS), one of the leading sunscreen agents, by forming inclusion complexes (IC) with methyl-beta-cyclodextrin (MCD). The IC shows maintained photostability for up to four hours of UV exposure and has potential in promoting its cosmetic application as a UVB sunscreen, as evidenced by biocompatibility tests.