The interaction of anthraquinones with a biological membrane model

• Grant number: 17/03910-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): May 01, 2017
• Effective date (End): April 30, 2018
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Maria Teresa Moura Lamy
• Grantee: Fernanda Lima Matos
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Since ancient times, anthraquinones are used as medicines. Currently, it is known that they have a wide variety of pharmacological activities. In particular, emodin and barbaloin have roused considerable interest in the scientific community, related to their characteristics and form of interaction with biological systems, including biological membranes. This project is a necessary complement, and an advance, in relation to previous studies, developed by A. R. Cunha and E. L. Duarte, in collaboration with M.T. Lamy and K. Coutinho. We propose here the study of the partition properties of emodin, in its neutral and charged forms, in DMPC (dimyristoyl phosphatidyl choline) vesicles in aqueous medium, through optical absorption and fluorescence techniques. DMPC bilayers will be used as a simple model of biological membranes. With barbaloin, we intend to study the protonation/deprotonation of this molecule in aqueous solution, for the determination of the pKa values of the molecule. Thus, the partition of their neutral and charged forms will be analyzed in DMPC membranes, allowing the comparison of the two systems, emodin/DMPC and barbaloin/DMPC. If possible, we will begin the structural study of the changes caused by barbaloin in DMPC membranes, in order to compare the effect and position of the two molecules, emodin and barbaloin, in the lipid bilayer. This study will be performed by differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR), with spin labels incorporated into the lipid bilayer. The main goal of this project is the better understanding of the mechanisms of biological action of the anthraquinones, and will be developed in collaboration with the Dr. A. R. Cunha, from Federal University of Maranhão, Campus Balsas, MA, and Dr. K. Coutinho, from the Institute of Physics, University of São Paulo, SP. (AU)