Antibacterial activity of rose bengal conjugated with hyaluronic acid

Massive and uncontrolled use of antibiotics caused the development of drug resistance in many types of pathogenic bacteria. Due to the worldwide spread of antibiotic-resistant bacteria, serious efforts are underway to find alternatives that overcome this resistance. One of the alternatives to antibiotic therapy is photodynamic therapy, based on the use of nontoxic dyes called photosensitizers, which are activated by harmless visible light. In this process, reactive oxygen species and free radicals are generated, providing a cytotoxic effect. The effectiveness of the method has been proven for a wide range of Gram-positive and Gram-negative bacteria. The coupling of photosensitizers with solid-phase carriers can expand the range of their applications.

Our study investigated the antibacterial effect of the photosensitizer Rose Bengal (RB) immobilized in hyaluronic acid (HA) with two types of linkers (ethylenediamine and propylenediamine) against the Gram-positive bacteria Staphylococcus aureus. Antibacterial activity was monitored by MIC (minimum inhibitory concentration) and viable cell-count methods. The photosensitizer conjugated with hyaluronic acid was effective against the pathogenic bacteria. A gradual release of RB enabled inhibition of bacterial growth over time, and the RB-HA conjugate was effective in inhibiting S. aureus bacteria for two months. Conjugation of RB with hyaluronic acid is therefore effective in inhibiting bacterial growth over time, based on the sustainability of the RB activity.