QSAR study on the relaxant agents from some Mexican medicinal plants and synthetic related organic compounds.

Quantitative Structure-Activity Relationship studies were performed to describe and predict the antispasmodic activity of some molecules isolated from Mexican Medicinal Flora as well as for some synthetic ones based on stilbenoid bioisosteres. The relaxant activity of these molecules was taken from experiments on rat and guinea-pig ileum tissues. Given that there is some evidence of species-specific on the relaxant effects, two data sets were proposed, one for rat ileum and the other for guinea-pig ileum. These data were statistically treated in order to find a Quantitative Structure-Activity Relationship model that could describe the corresponding biological models. The goodness of prediction for the best models was measured in terms of the Leave-One-Out Cross-Validation R(2) (LOO q(2)) and the correlation coefficients of regressions through the origin (RTO R(2)0). Results show that papaverine activity could not be used as reference in rat ileum tests; however, this molecule can be used as a good reference molecule in guinea-pig ileum tests. Our study shows that MATS5p and R8m+ descriptors are the most important descriptors in predicting the rat ileum activity and that atomic polarizability is the main atomic property. On the other hand, the R3u GETAWAY descriptor turns out to be important in predicting the guinea-pig ileum activity where the influence/distance of substituents on these molecules could describe the observed activity.