Linear discriminant and multiple regression analyses of anticoccidial triazines.

Quantitative structure-activity relationships among some anticoccidial 2-(substituted-phenyl)-1,2,4-triazine-3,5-(2H,4H)-diones were studied by multiple regression analysis (MRA, the Hansch approach) and by linear discriminant analysis (LDA). With MRA the potencies of these compounds are correlated with their reverse-phase HPLC retention times and their 1H NMR chemical shifts at the 6-position. While the coefficients of the variable terms are significant, the moderate R2 (0.56) of the correlating equation suggests that predictions made from this analysis are not likely to be accurate. LDA supports the idea that these descriptors are related to potency, but the discriminant function does not lead to good classification. However, when coupled with a graphic display of the results, LDA gives a more immediate sense of the synthetic direction to take when seeking highly potent analogues. It is apparent that other important but not yet identified factors also play a role in determining the potencies of these compounds.