Degradation Studies of Human Serum Albumin in Presence of Diimine Cr(III) Complex, Cr(5clphen)3 3+

A. VELO; P. F. GARCIA; G. A. ARGÜELLO

Córdoba Capital

Conferencia; 16th International Conference of Photobiology; 2014

It?s well known that Human Serum Albumin (HSA) is one of the most abundant macromolecules inthe human body and it?s the responsible to carry a wide variety of substances to the blood plasma. On theother hand, we proposed tris(5-Cl-1,10phenanthroline) Chromium (III) as a potential drug forPhotodynamic Therapy (PDT), Therefore we believe that HSA may be a good carrier of ourphotosensitizer, Cr(5Clphen)33+.Previous studies have demonstrated (according to Bhattacharya and Ross and Subramanian models)that this complex binds to the HSA in a spontaneous process with positive changes of entropy andenthalpy concluding that the interaction between the Cr(III) complex and the HSA were mainlyhydrophobic, although the electrostatic interactions could not be discarded.In this work we carried out experiments in order to determine conformational changes in the proteinupon the association with the chromium complex. Using the Circular Dicroism (CD) technique we coulddetermine that no changes were produced in the secondary structure of the protein when the complexbinds to it.To evaluate the photodegradation of the protein due to the reaction with the excited state of the Cr(III)complex, we carry out electrophoretic experiments. The results showed that degradation was dependentof the irradiation time and occurred both in the absence and in the presence of oxygen (most favored). Inorder to evaluate the presence of ROS, we modified the ―COLESTAT‖ assay (usually used for detectionof cholesterol) to quantify the H2O2 formed by the excited sate of the complexes. Results of this assayshow that the family of diimine Cr(III) complex generates H2O2 by the excited state which is an importantfact, because it represents a hazard to the tumoral cells.Acknowledgments: INFIQC for providing resources and equipment