Using molecular dynamics to study the effect of cis sodium crocetinate (CSC) versus trans sodium crocetinate (TSC) on the diffusion of oxygen in water

Trans Sodium Crocetinate (TSC) is currently being studied for the treatment of hemorrhagic shock. The drug has been shown to increase oxygen consumption in laboratory animals that have lost blood. The mechanism by which TSC acts is still not completely understood; however, it has been suggested to increase the diffusion of oxygen in aqueous systems (such as blood plasma). A previous molecular dynamics simulation suggests that TSC, due to a hydrophobic interaction with water, increases the diffusivity of oxygen through water.; That investigation examined only the effect of the trans isomer. The current study is designed to also examine the effect of the cis isomer. This isomer was chosen because previous laboratory experiments suggested that a mixture of trans and cis isomers did not increase the oxygen diffusivity to the same extent as the pure trans isomer. Thus, TSC is a much more robust drug in terms of its effectiveness over a larger concentration range.; This research uses the readily available molecular dynamics software package TINKER to compare the effects of the two isomers on both oxygen diffusion and water self-diffusion. The results match the previous research in showing that TSC increases the oxygen diffusion coefficient while causing no change in the water self-diffusion coefficient. The cis isomer (CSC) causes no change on the water self-diffusion, and shows less of an effect on the oxygen diffusivity than the TSC does. Since the simulations suggest that oxygen never gets close to either TSC or CSC, these effects are thought to be due to longer range effects on the water structure. Radial distribution functions suggest that TSC and CSC affect the water structure differently and it is proposed that this is responsible for the greater effect of TSC on oxygen diffusivity.