  We have performed Molecular Dynamics simulations of ectoine, hydroxyectoine
and urea in explicit solvent. Special attention has been spent on the local
surrounding structure of water molecules. Our results indicate that ectoine and
hydroxyectoine are able to accumulate more water molecules than urea by a
pronounced ordering due to hydrogen bonds. We have validated that the charging
of the molecules is of main importance resulting in a well defined hydration
sphere. The influence of a varying salt concentration is also investigated.
Finally we present experimental results of a DPPC monolayer phase transition
that validate our numerical findings.
