Efficacy and activity prediction by molecular topology of new drugs against the Tetranychus urticae plague

Tetranychus urticae Koch is an important pest affecting citrus, for which biological control has not yet been achieved; therefore, acaricides are commonly used instead. The goal of the work reported in this paper was to measure the efficacy of different new compounds —uracil derivatives— on this mite and conduct a quantitative structure-activity relationship (QSAR) study based on the results obtained, in order to set up a model capable of predicting the acaricidal activity of further new compounds. Some of the tested new products proved highly effective against T. urticae. Besides, topological indices were used as structural descriptors. The result was a topological model consisting of two discriminant functions for distinguishing between active and inactive compounds, and a predictive equation for the adult mortality percentage on the sixth day. This model was then sequentially applied to a large database of compounds with unknown activity against the Tetranychus urticae plague. Finally, a preliminary toxicity study of the most effective novel compounds supports their non-toxicity, performing even better than commercial referents.