2D-QSAR: The Mathematics behind the Drug Design Methodology

The development of quantitative structure-activity relationships (QSARs or 2D-QSARs) is a science that has developed without a defined framework, series of rules, or guidelines for methodology. It has been more than 40 years since the QSAR paradigm first found its way into the practice of agrochemistry, pharmaceutical chemistry, toxicology, and eventually most facets of chemistry. Its staying power may be attributed to the strength of its initial postulate that activity is a function of structure as described by electronic attributes, hydrophobicity, and steric properties as well as rapid and extensive development in methodologies and computational techniques that have ensued to delineate and refine the many variables and approaches that define the paradigm. The overall goals of QSAR retain their original essence and remain focused on the predictive ability of the approach and its receptiveness to mechanistic or diagnostic interpretations. Our intention with this chapter is to offer the basis of the QSAR approach in a clear and intuitive way, with maximum simplification and trying to close the gap that exists between maths and students of pharmacy. Moreover, the interpretation of the equations is even more important than statistically obtaining significant and robust relationships. We will show our results on Choline Kinase (ChoK) inhibitors as antiproliferative agents to demonstrate the possibilities of the Hansch model in the drug design process.