title: Fluorometric Investigation on the Binding of Letrozole and Resveratrol with Serum Albumin.
abstract: Breast cancer is the most common cancer in women worldwide. Combination of drugs during long-therm cancer therapy can increase free, biological active form of the drug and cause dangerous side effects. The 21&lt;sup&gt;st&lt;/sup&gt; century is a period of searching for a progress in cancer chemotherapy. The simultaneous dosage of drugs and natural agents isolated from fruits and vegetables used in breast cancer treatment could be more effective and less toxic. The aim of the study was to determine the binding sites of both letrozole (LET) and polyphenol product, resveratrol (RES) in tertiary structure of human serum albumin (HSA) based on the fluorescence spectroscopy. The binding of LET and RES to HSA was studied by monitoring the changes in emission fluorescence spectra of albumin in the presence of ligands at 280 nm and 295 nm excitation wavelengths. To identify the binding sites of LET and RES on HSA, warfarin (WAR) and 5-(Dimethylamino)-1-naphthalenesulfonamide (DNSA) were used as site probes for binding site I, while dansyl-L-proline (DP) was studied as a marker for binding site II. The binding sites for LET and RES in HSA were found to be located in subdomain IIIA. Based on the Stern - Volmer and binding isotherm using non-linear regression methods, the formation of complexes of LET and RES with HSA and association constants were obtained. The binding analysis showed that the association constants indicated a stronger interaction of HSA with RES than LET and the presence of RES in the tertiary system alters the stability of LET-albumin complex. This conclusion points to the necessity of precaution and monitoring therapy when resveratrol as a natural compound and letrozole are used together.
authors.forename: Monika
authors.initials: M
authors.lastname: Maliszewska
authors.affiliation: School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Chair and Department of Physical Pharmacy, 41-200 Sosnowiec, Jagiellońska 4, Poland. mmaciazek@sum.edu.pl.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Maciążek-Jurczyk
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Pożycka
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szkudlarek
authors.forename: Mariola
authors.initials: M
authors.lastname: Chudzik
authors.forename: Anna
authors.initials: A
authors.lastname: Sułkowska
mesh_terms: D047072:Aromatase Inhibitors / Q000737:chemistry*; D005470:Fluorometry / Q000379:methods*; D006801:Humans; D000077289:Letrozole; D009570:Nitriles / Q000737:chemistry*; D011485:Protein Binding; D000077185:Resveratrol; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013267:Stilbenes / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry*
chemical_list: D047072:Aromatase Inhibitors; D009570:Nitriles; D012709:Serum Albumin; D013267:Stilbenes; D014230:Triazoles; D000077289:Letrozole; D000077185:Resveratrol