The substituent entropy constant .SIGMA.X(X=S0) used in the QSAR investigation of dihydrofolate reductase inhibition by Baker triazines.
HIDEKO KAWAKI, Tatsuya Takagi, Akihiro Iwata, Yoshio Sasaki · Chemical and Pharmaceutical Bulletin · 1982
QSAR analysis of dihydrofolate reductase inhibition by Baker triazines - 4, 6-diamino-1, 2-dihydro-2, 2-dimethyl-(x-substitutedphenyl)-s-triazines - was achieved for 21 congeners by the linear combination of the four kinds of parameters (σs°)2, σs°, σi and σπ· The successful result is expressed by the equation, log (1/C) =-25.29 (±7.58) (σs°)22+7.04 (±2.64) σs°3, 4+3.22 (±1.68) |σi|3, 4+3.68 (±3.22) |σπ|+6.37 r=0.981, SE=0.09, F=103.7 Subscripts 2, 3 and 4 denote the positions of the x substituents. This suggests that a four parameter analysis of this type is the most promising in QSAR analyses.