Geometrical Isomers of Dantrolene and Their Interactions with Calcium and Magnesium Cations

Geometrical isomers of dantrolene are considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p). Dantrolene is a skeletal muscle relaxant which interferes with the release of calcium ion from the sarcoplasmic reticulum. On the other hand, some evidence exists that dantrolene is Mg2+-dependent at least in certain species. Therefore, the present study not only considers the geometrical isomers of dantrolene but also focused on the interaction of isomers of dantrolene with Ca+2 and Mg+2 ions at the molecular level. All the systems of present interest have exothermic heat of formation values and favorable Gibbs free energy of formation values. They are electronically stable. In the case of composite from the anti isomer, Ca+2 or Mg+2 ion locates itself in the cavity/fjord formed in the composite of dantrolene whereas in the syn composite, Mg+2 prefers a location outside the cavity/fjord of the composite molecule. Various quantum chemical data have been collected and discussed including UV-VIS spectra.