AN ACTION SPECTRUM FOR BLUE AND NEAR ULTRAVIOLET IN ACTIVATION OF Propionibacterium acnes; WITH EMPHASIS ON A POSSIBLE PORPHYRIN PHOTOSENSITIZATION

Abstract

—Propionibacterium acnes (P. acnes), grown on Eagles medium with different pH. were irradiated with monochromatic light in the range 320 to 440 nm. Different pH leads to different porphyrin concentrations in the cells. The light sensitivity of the bacteria was estimated from the reduction in their ability to form colonies after radiation. The sensitivity was highest for the lowest wavelength (320 nm). and decreased continuously with increasing wavelength up to 380 nm. In the region between 380 and 440 nm there was a second maximum (at 415 nm) which corresponds to the maximum absorption ol the fluorescing porphyrins in P. acnes. The sensitivity to 415 nm light was found to be dependent on the endogenous porphyrin concentration in the cells. while the sensitivity to 320 nm radiation was independent of the amount of porphyrin present. These results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteria.

Porphyrin Photosensitization and Phototherapy

“…Bacteria of the strain Propionibacterium were found to accumulate significantly more HPD than did the other strains tested. Propionibacterium acnes also produces porphyrins endogeneously, mainly PP and CP (Kjeldstad et al, 1984). The production was found to be pH-dependent with an optimum at pH 6.1.…”

Blue and red light combination LED phototherapy for acne vulgaris in patients with skin phototype IV

“…This reaction stimulates production of reactive free radicals and singlet oxygen species, which results in destruction of the bacteria [14][15][16][17][18][19][20][21][22][23]. Although the bacterial sensitivity to light becomes higher as the wavelength gets shorter, there exists a second absorption peak at 415 nm, which corresponds to that of coproporphyrin III, the predominant bacterial porphyrin produced by P. acnes [15,21,33,34].…”

“…Recently, it has been revealed that visible light activates the endogenous porphyrins of P. acnes, which results in a photodynamic reaction to destroy the bacteria [14][15][16][17][18][19][20][21][22][23]. The absorption peak of the bacterial porphyrins is at 415 nm, which falls into the blue light waveband [15].…”

“…The absorption peak of the bacterial porphyrins is at 415 nm, which falls into the blue light waveband [15]. Many clinical studies have demonstrated the efficacy of blue light phototherapy for acne with various success rates [24][25][26][27][28][29][30][31].…”

Modern Methods of Acne Treatment in Children

“…It has long been known that natural light allows reducing acne intensity: firstly, ultraviolet radiation has bactericidal effect; secondly, it suppresses skin inflammatory processes [27,28]. Data of these trials stimulated development of new methods of acne treatment with lasers and other light sources.…”