Dark Antibacterial Activity of Rose Bengal

Abstract

The global spread of bacterial resistance to antibiotics promotes a search for alternative approaches to eradication of pathogenic bacteria. One alternative is using photosensitizers for inhibition of Gram-positive and Gram-negative bacteria under illumination. Due to low penetration of visible light into tissues, applications of photosensitizers are currently limited to treatment of superficial local infections. Excitation of photosensitizers in the dark can be applied to overcome this problem. In the present work, dark antibacterial activity of the photosensitizer Rose Bengal alone and in combination with antibiotics was studied. The minimum inhibitory concentrations (MIC) value of Rose Bengal against S. aureus dropped in the presence of sub-MIC concentrations of ciprofloxacin, levofloxacin, methicillin, and gentamicin. Free Rose Bengal at sub-MIC concentrations can be excited in the dark by ultrasound at 38 kHz. Rose Bengal immobilized onto silicon showed good antibacterial activity in the dark under ultrasonic activation, probably because of Rose Bengal leaching from the polymer during the treatment. Exposure of bacteria to Rose Bengal in the dark under irradiation by electromagnetic radio frequency waves in the 9 to 12 GHz range caused a decrease in the bacterial concentration, presumably due to resonant absorption of electromagnetic energy, its transformation into heat and subsequent excitation of Rose Bengal.

A study of Rose Bengal against a 2-keto-3-deoxy-d-manno-octulosonate cytidylyltransferase as an antibiotic candidate

“…Rose Bengal is an organic anion dye that has been clinically used for decades and has been used to assess eye surface epithelium damage of eye surface disease 38 . Also, it is a water-soluble photosensitiser with a distinctive wine colour 39 . It is well known that singlet-oxygen production of Rose Bengal after exposure with 300-600 nm radiation increases the antibacterial effect [40][41][42][43] .…”

Different Aspects of Using Ultrasound to Combat Microorganisms

“…The term sonodynamic antimicrobial chemotherapy (SACT) refers to the application of this strategy to kill microorganisms. [3,[100][101][102][103] As in photodynamic treatment, sonodynamic treatment is based on the combined action of three components: US, sensitizer, and molecular oxygen. Some molecules exhibiting photodynamic activity produce free radicals when irradiated with US.…”

“…In our later studies, Rose Bengal was immobilized onto silicone, and in this case the Rose Bengal also showed significant antibacterial activity against S. aureus in the dark under ultrasonic activation, probably due to Rose Bengal leaching from the polymer during ultrasonic treatment. [102] Since Rose Bengal possesses both photo-and US-sensitive properties, it has been the subject of scientific attention. [107] Costley et al demonstrated the sonodynamic antibacterial activity of Rose Bengal when conjugated to an antimicrobial peptide KLAKLAK against planktonic cultures of S. aureus and P. aeruginosa, as well as P. aeruginosa biofilms, and in vitro and in vivo mouse models.…”

A triple‐targeting inhibitory activity of Rose Bengal on polysaccharide biosynthesis of Burkholderia pseudomallei

“…Then, the acceleration of enzyme activity by adding a small amount Rose Bengal is a water-soluble photosensitizer [28] producing singlet oxygen after exposure to 300-600 nm radiation. [29] Its antibacterial and anticancer activities have been clinically applied to various diseases.…”