Antiseptics and the Ocular Surface: In Vitro Antimicrobial Activity and Effects on Conjunctival and Corneal Epithelial Cells of a New Liposomal Ocular Spray Containing Biosecur® Citrus Extract

Introduction: The study aimed to evaluate the in vitro antimicrobial activity of a new liposomal ocular spray containing the antiseptic Biosecur® citrus extract (Oftasecur, OFFHEALTH, Florence, Italy) and its in vitro effects on cultured human corneal and conjunctival cells. Methods: Minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of Oftasecur against Candida albicans and Gram-positive and Gram-negative bacteria, including antibiotic-resistant strains, were determined. Human corneal and conjunctival epithelial cells in vitro were incubated for 10 and 30 min with Oftasecur or its components. The cytotoxicity was assessed through the release of cytoplasmic enzyme lactate dehydrogenase (LDH) into the medium; the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate the cell viability. Results: Oftasecur was active at dilutions ranging from 1:2 to 1:16 and it displayed bactericidal and fungicidal effect against all assayed microorganisms. Most of the reduction of Staphylococcus epidermidis vitality (65%) occurred within the first minute of exposure. The cytotoxicity of Oftasecur was similar to its vehicle, and the cell viability was significantly reduced only by Oftasecur in its undiluted form. Conversely, Biosecur induced a significant cytotoxicity in all the experiments. Conclusion: Oftasecur showed a rapid and wide-spectrum antibacterial activity, with an optimal in vitro tolerability profile.