An in vitro study of the photodynamic effect of rose bengal on trichophyton rubrum

Abstract

Onychomycosis, a fungal infection of the finger or toenails, is predominantly caused by Trichophyton rubrum. Treatment is difficult due to high recurrence rates and problems with treatment compliance. For these reasons, alternative therapies are needed. Here we describe the photoactivation of Rose Bengal (RB) using a green laser (λ = 532 nm) at fluences of 68, 133 and 228 J/cm(2) , and assess its fungicidal activity on T. rubrum spore suspensions. A 140 µM RB solution was able to induce a fungicidal effect on T. rubrum when photosensitized with the fluence of 228 J/cm(2) . RB photosensitization using a green laser provides a potential novel treatment for T. rubrum infections.

Modern trends in biophotonics for clinical diagnosis and therapy to solve unmet clinical needs

“…The photoactivation of RB was described for the fungicidal activity on suspensions Trichophyton rubrum spores using a laser wavelength of 532 nm at fluences of 68 J/cm 2 , 133 J/cm 2 and 228 J/cm 2 . Trichophyton rubrum causes fungal infection of the finger or toenails .…”

Light treatments of nail fungal infections

“…It has been suggested that the phototoxic action of RB is limited only to the cell membrane, as its polar nature restricts its intracellular accumulation . However, there is also evidence of intracellular RB accumulation, including the vacuoles of T. rubrum and mitochondria of Cryptococcus neoformans via fluorescence imaging . SEM imaging has also shown evidence of RB causing intracellular morphological changes to human melanoma cells, including vacuolization and mitochondrial distortion, thus supporting its ability to accumulate within cells .…”

“…In a pilot study by Lauto et al , it was found that RB‐PDT with a 532 nm diode‐pumped solid state laser eradicated or strongly reduced growth of T. rubrum spores. A concentration of 140 μM RB was used and incubated with the spore suspension for 30 minutes, followed by 5 minutes of irradiation at a fluence of 228 J/cm 2 .…”

“…The same methodology has been applied successfully in a recent pilot study with 6 patients with toenail onychomycosis, achieving complete cure using 763 J/cm 2 irradiation . Due to the scattering of light by the nail plate (roughly ~50% ), a higher fluence was required.…”

Change of photosensitizer fluorescence at its diffusion in viscous liquid flow

“…It was shown earlier 1 that bengal rose penetrates into cells located in cytoplasm and connects on peptides, at this time bengal rose interests as a photosensitizer. 2 Solutions of bengal rose dissolved in phosphate bu®er (pH ¼ 7:4), blood serum albumin (concentration 8% (weight)) and suspension of cancer mammary cells of BYRB mice line prepared for method 3 were used as a model media. For spectral measurements the obtained cell suspension was centrifuged at 4000 min À1 5 min with supernatant removal and next addition of phosphate bu®er.…”