Quantitative-Structure Activity Relationship (QSAR)
Thirumoorthy Durai Ananda Kumar · 2022
Quantitative-structure activity relationship (QSAR) examines series of related compounds and assigns parameters for their substituent groups. QSAR strategy establishes the mathematical relationship between the biological activity and bio-physicochemical properties of molecules. Lemke described the solubility characteristic of drugs through carbon solubilizing potential constants. The carbon solubilizing potential of the molecule is indicative of solubility. The most important solubility descriptors for QSAR analysis are: partition coefficient, diffusion coefficient, hansch substituent constant, and fragmentation constant. The molecules electron distribution pattern determines the drug-receptor interaction and the biological activity. The electronic parameters are useful in calculating electron donating or electron withdrawing nature of the substituents. Flourine is strongly electronegative and possess prominent inductive effect. In enzyme inhibitors, fluorine is substituted for hydrogen is general. Inductive effect of fluorine reduces their enzymatic inactivities. The fluorine substitution exerts diminished electron withdrawal effect at distal sites and donates a lone pair of electrons by resonance. The opposing resonance and field effects are referred as mesomeric effect.