EFFECTS OF ETHEPHON ON SATURATED AND UNSATURATED PHOSPHATIDYLCHOLINES FORMING MONOLAYERS

The increase demand for food and, consequently, the need to increase crop productivity have led to the widespread use of pesticides around the world. Among the pesticides, we highlight ethephon, a growth regulator of the ethylene chemical group. Studies related to the exposure of pesticides such as ethephon in living organisms are important to understand the harmful effects they can cause, especially related to the biological changes in humans. Due to the fundamental properties of the plasma membrane in maintaining cell integrity and acting as a selective barrier to most external agents, in this study we used lipid monolayers as mimetic membrane systems, formed of phosphatidylcholines (CP), aiming the investigation of possible effects caused by ethephon in these models. The interaction of phospholipids DPPC, POPC and DOPC with ethephon was investigated by analyzing π-A isotherms, compressional modulus and infrared absorption and reflection spectroscopy with modulated polarization (PM-IRRAS), obtained from Langmuir monolayers. The π-A isotherms showed that the ethephon interacts at the air/water interface with the POPC and DOPC, causing displacement in the isotherms. The PM-IRRAS showed that, although displacements in DPPC isotherms are not observed, there is interaction of ethephon with the head-choline and phosphate groups. Despite the interactions, there was no lipid phase change of the monolayers in the presence of ethephon for any of the studied lipids. Thus, it can be concluded that, in these experimental conditions, ethephon can interact with the monolayers of the three phospholipids studied and the interactions are greater for unsaturated phospholipids.