Date Published: March 18, 2018
Publisher: Tabriz University of Medical Sciences
Author(s): Medhat Wahba Shafaa, Amany Hasan Elshazly, Amira Zaki Dakrory, Maha Reda Elsyed.
Purpose: To stress the influence of Coenzyme Q10 (CoQ10) on the structural properties of liposomes as model membranes and to investigate the possible role of CoQ10 or CoQ10 doped in liposomes when topically instilled as eye drops, in preventing cataract.
Phospholipids, such as phosphatidylcholine, are major targets that are subject to the damage caused by free radicals in cellular membranes. Lipid oxidation that causes cellular damage is strongly associated with ageing, carcinogenesis and other diseases.1 Free radicals (which are molecules or atoms with unpaired electrons) are passivated by reducing agents. Therefore, they are defined as antioxidants as they limit the oxidative damage to biological structures. Imbalance between pro-oxidant and antioxidant agents is termed oxidative stress, which in may result in oxidative damage. The state oxidative stress results in the elevation of free radicals which can react with cellular lipids, proteins, and nucleic acids leading to local injury and eventual organ dysfunction. Lipids are, probably, the most susceptible bio-molecule to be attacked by free radicals.
L-a-Dipalmitoyl phosphatidylcholine (DPPC) in powder form and of purity 99% of molecular weight of 734 was used in this work. DPPC, Dicetyl phosphate (DCP), molecular weight of 546.9 of purity 99% and, Stearyl amine (SA), molecular weight of 269.5 of purity 99% were all purchased from Sigma (ST. Louis, Mo, USA). Trizma buffer, molecular weight of 121.1, Coenzyme Q10 (CoQ10), molecular weight of 863.358 were purchased from EIPICO, Egypt. All other reagents and solvents used in this work were of research grade.
DSC is a fundamental technique for the characterization of membrane behavior, providing all thermodynamic parameters for temperature-induced transitions. The temperature at which a transition from the gel phase to the rippled phase takes place is called the pre-transition temperature and it is mainly related to the polar region of phospholipids. Subsequently, the melting of bilayer from the rippled phase to the liquid phase occurs at the main transition temperature (Tm). The melting point (Tm) represents the peak temperature of the endotherm for the lipid gel-to fluid phase transition recorded during the heating scan.
CoQ10, when incorporated in lipid bilayers, interacts actively with lipids and induces changes in their physico-chemical properties. In addition, a possible location of CoQ10 in the interfacial region of the membrane has been proposed. The present data clarify, to a certain extent, the molecular interactions of CoQ10 with membrane systems and may additionally contribute to a better understanding of CoQ10 physiological properties and the development of therapeutically advanced systems.
The experiment was performed in accordance with the ARVO rules for use of animals in ophthalmic and vision research.
The author reports no conflicts of interest.