New approach on Tyrosine photosensitized oxidation mechanism?

NEYRA RECKY, JAEL R.; MARIANA P. SERRANO; ANDRÉS H. THOMAS; M. LAURA DÁNTOLA; CAROLINA LORENTE

Viña del Mar

Congreso; XIV Encuentro Latinoamericano de Fotoquímica y Fotobiología (XIV ELAFOT); 2019

Universidad de Santiago de Chile

The main goal of this work is to elucidate the pathways involved in the photogeneration of DOPA and dopachrome, by evaluating the role of reactive oxygen species (ROS) and Tyr(-H)?. Acid aqueous solutions (pH 6.0) containing Ptr (60µM) and Tyr (100µM) were exposed to UV-A radiation (365 nm) for different periods of time and in different experimental conditions: (i) in the presence of superoxide dismutase (SOD) (0 ? 50 U/mL), to evaluate the role of O2??; (ii) in D2O to evaluate the role of 1O2; and (iii) in presence of resveratrol (RSV), a natural antioxidant inhibitor of type I photooxidation mechanism, to evaluate the role of (Tyr(-H)?). The results obtained using different experimental conditions suggest that the main products previously reported (Tyr2, DOPA and dopachrome) are generated from Tyr(-H)?. The experiments perfomed in the presence of SOD, confirmed that DOPA is a product of the reaction between Tyr(-H)? and O2?-. On the other hand, the contribution of 1O2 to the formation of these oxidation products may be discarded.