Molecular dynamics study of the properties of capsaicin in an 1-octanol/water system

Molecular dynamics simulations were performed to study the behavior of capsaicin in an 1-octanol/water system at 298 K and 1 bar. Capsaicin is the pungent chemical found in chili pepper that stimulates our sensory system resulting in a burning, pain sensation. In the first step toward investigating the activity of capsaicin, we have used two molecular representations for capsaicin based on the OPLS force field: all-atom and united-atom models. The octanol/water mixture was selected as a model system to determine the hydrophobic and hydrophilic properties of capsaicin by analyzing equilibrium, structural, and dynamic properties from the simulations. Our simulations showed that capsaicin preferentially partitions to the octanol phase, with its hydrocarbon segment oriented with that in octanol, while the polar part remains exposed to the aqueous phase. The simulations with the all-atom and united-atom models yielded similar results.