Prediction of Quinolone Activity against Mycobacterium avium by Molecular Topology and Virtual Computational Screening

We conducted a quantitative structure-activity relationship study using a database of 158 quinolones previously tested against Mycobacterium avium-M. intracellulare complex in order to develop a model capable of predicting the activity of new quinolones against the M. avium-M. intracellulare complex in vitro. Topological indices were used as structural descriptors and were related to anti-M. avium-M. intracellulare complex activity by using the linear discriminant analysis (LDA) statistical technique. The discriminant equation thus obtained correctly classified 137 of the 158 quinolones, including 37 of a test group of 44 randomly chosen compounds. This model was then applied to 24 quinolones, including recently developed fluoroquinolones, whose MICs were subsequently determined in vitro by using the Alamar blue microplate assay; the biological results confirmed the model’s predictions. The MICs of these 24 quinolones were then treated by multilinear regres-sion (MLR) to establish a model capable of classifying them according to their in vitro activities. Using this model, a good correlation between measured and predicted MICs was found (r 2 � 0.88; r 2 cv [cross-validation correlation] � 0.82). Moxifloxacin, sparfloxacin, and gatifloxacin were the most potent against the M. avium-M. intracellulare complex, with MICs of 0.2, 0.4, and 0.9 �g/ml, respectively. Finally, virtual modifications o