Quantitative structure antitumoral-activity relationships of thiadiazinthione derivatives using the novel hybrid molecular index pMRchi.

Purpose: The recently defined molar-refractivity-partition index was applied to a family of 1,3,5- thiadiazin-2-thione derivatives in order to establish quantitative structure-antitumoral models. The goal of this effort is to establish the relationships between the structure and biological response of these compounds.
Method: After the splitting of the sample in two sets, their indices were correlated against the measured biological activity. The combined use of our index with others had been able to describe not only the topologic but also the London dispersive forces of any fragment in relation to the biological response of the sets.
Results: The obtained models showed correlation coefficients of 0.87 and 0.81 respectively linking structural and biological features of the molecules. The mean relative error values were less than 7%. According to the models, the activity of the first sample is related mostly to molecular topology and dispersive forces. Sample two activity was associated to the size and branching of the substituents, and also to the London forces.
Conclusion: The index was able to discriminate between pure topological features and those related to dispersive forces.