Parietin, an anthraquinone derivative isolated from Teleoschistes flavicans, as photosensitizer Type I.

LAURA RAQUEL COMINI; SUSANA NUÑEZ MONTOYA; NATALIA JELICICH; GABRIELA VERGARA; JULIANA MARIONI; JOSE LUIS CABRERA

Encuentro; XII ENCUENTRO LATINOAMERICANO DE FOTOQUÍMICA Y FOTOBIOLOGÍA, ELAFOT; 2015

Since several years anthraquinone (AQs) derivatives have been thoroughly studied in relation to their photosensitizing properties in photodynamic reactions [1]. On the basis of this, some of them showed good antibacterial and antiviral effects, by photosensitization of reactive oxygen species (ROS) such as superoxide anion (O2.¯) (Type I mechanism) and singlet molecular oxygen (1O2) (Type II mechanism), with subsequent oxidative damage [2]. This time we report the type I photosensitizer properties of parietin (PTN), an AQ isolated from vegetal specie: Teleoschistes flavicans (SW) Norm. (Telochistaceae) [3].The production of O2.¯ was detected and quantified with an indirect relative photobiological method that measures the reduction of Nitroblue Tetrazolium (NBT) to blue formazan by O2.¯ generated inside human leukocytes when an oxidizer (AQ-PTN) is present in the dark and under continuous UV-Vis radiation (380?480 nm, with a maximum at 420 nm - 0.65 mW/cm2). The absorbance of blue NBT formazan intracellular was measured with respect to basal production and was expressed in percentage. According to the results, to 5 and 10 mg/mL, PTN causes an increase in the percentage of production of O2-. under irradiation with respect to dark condition (Table1).However, to 20 mg/mL and dark conditions, the methodology used shows that the percentage of production of O2-. is less than that generated to 5 and 10 mg/mL and even under irradiation, this percentage was equal to the condition basal (0.0 ± 0.0). The latter results could be due to that to 20 mg/mL there is excessive generation of ROS in dark condition and even more under irradiation, causing a major oxidative damage in the leukocytes with eventual cell death.In conclusion, it was shown that PTN is a good photosensitizer type I and this is directly dependent on the concentration used.References[1] I. Gutiérrez, S.G. Bertolotti, M.A. Biasutti, A.T. Soltermann, N.A. García. Can. J. Chem. 1997, 75, 423.[2] K. Zerdin, M.A. Horsham, R. Durham, P. Wormell, A.D. Scully. Reac.Funct.Polymers.2009, 69, 821.[3] L. Comini, F. Moran, R. Mignone, S. Núñez Montoya, J. Marioni, J. Cabrera and C. Borsarelli. 16th Internacional Congress of Photobiology. Argentina. 2014.