Quantitative structure-activity relationship of DDT analogs

A quantitative structure-activity relationship (QSAR) has been carried out for Phormia regina toxicity by a set of 24 p,p′-disubstituted analogs of DDT. The toxicity data are from the extensive studies of R. L. Metcalf. Preliminary examination of the data indicated that toxicity was parabolically related to molar refractivity, MR, of the ring substituents. This enabled parabolic regression to be evaluated. Multiple regression analysis relating toxicity and the substituent constants MR, Taft steric parameter (E_s), hydrophobicity (π), and polar effect (σ) showed that MR dominated the regression equations. The implication of these physicochemical properties in the interaction of DDT analogs with the receptor site is discussed.