Hexachlorophene and triclosan - Exploratory ab initio structural analyses

Hexachlorophene is primarily used as an antiseptic in germicidal soaps but can be toxic if absorbed through the skin. Rotation of its benzene rings about the two central methyl bonds gives rise to a variety of minima characterized by intramolecular hydrogen bonding. Triclosan is an antibacterial currently used in a wide range of consumer goods, from drugs to hand soaps. With the emerging resistance of bacteria to triclosan, researchers now consider hexachlorophene as a possible option in the design of antibacterial drugs. Clinical studies have demonstrated that these two molecules, though comparable in structure, bind to different adjacent sites in bacterial Enoyl-ACP Reductase (FabI), which is used in fatty acid synthesis. This significant discovery is attributed to subtle structural disparities between the two compounds. Determination of the conformations adopted in vitro and in vivo is crucial in elucidating the binding mechanism of these two compounds. Ab initio structural analyses have been performed on these two molecules using GAUSSIAN98 software.