Photodynamic properties and photoinactivation of Candida albicans mediated by brominated derivatives of triarylmethane and phenothiazinium dyes

M. GABRIELA ALVAREZ, M. NOEL MONTES DE OCA, M. ELISA MILANESIO, CRISTINA S. ORTIZ AND EDGARDO N. DURANTINI

Photodiagnosis Photodynamic Therapy

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 11 p. 148 - 155

1572-1000

The photodynamic activity of brominated derivatives of New Fuchsin and AzureB was studied in solution and in cell suspensions of Candida albicans. The spectroscopic andphotodynamic properties of these photosensitizers were compared with those of Crystal Violetand Azure B, which represent active photosensitizer related to each family of compounds.Triarylmethane derivatives absorb intensely with a band centered at 570 nm, while the phenothiazinium dyes at 650 nm. Photooxidation of 9,10-dimethylanthracene was observed usingphenothiazinium compounds indicating the formation of singlet molecular oxygen, while it wasnot detected using triarylmethane agents. However, triarylmethane dyes were able to photooxidizeL-tryptophan. In yeast cell suspensions, the photosensitized inactivation of C. albicansincreases with photosensitizer concentration, causing a 5 log decrease of cell survival, whenthe cultures are treated with 20 uM of Crystal Violet and irradiated for 60 min. Under these conditions, the photodynamic activity of 50 uM Azure B induced a 3 log decrease of cell survival. Studies of photodynamic action mechanism indicated that photoinactivation of C. albicans cells induced by triarylmethane compounds involves mainly type I photoprocess. Although, phenothiazinium derivatives produce singlet molecular oxygen, a contribution of other reactive oxygen species cannot be discarded in the photoinactivation of C. albicans.