Hansch correlations

The structure-activity relationships of thyroid hormones and related structural analogs have been studied using both qualitative and quantitative methods, including the Hansch correlation. The structural requirements for receptor binding, and therefore hormone activity, are ... 

Lien, E.J., and C. Hansch, Correlation of ratios of drug metabolism by microsomal subfractions with partition coefficients. J Pharm Sci, 1968. 57(6) 1027-8. 

Hansch Correlations of TFMS Herbicidal Activity. Stepwise regression techniques were used to correlate the pre-emergence herbicidal activity data gathered for all three weed types with one or more of the following appropriate general forms of the Hansch equation (cf. Equations 2 and 6 and Table VI). 

Table VIII. Effect on Statistics of Hansch Correlation of Separating TFMS Herbicides into Meta- and Para-Substituted Series...

Methylthio TFMS Derivatives. Data for the meta- and para-substituted methylthio TFMS derivatives (3-SCH3, 4-SCH3) were not included in Hansch structure—activity correlations for the several weed types. This omission was a result of our noting that when herbicidal data for the methylthio derivatives were included in fits, much poorer Hansch correlations were obtained. This was true whether or not the TFMS compounds were separated into meta- and para-derivatives for fitting purposes. It was also true for all weed types examined, in the presence and absence of surfactant. A typical example of the improvement in statistical parameters effected by omitting methylthio points from the data pool is illustrated by the following Hansch correlation of TFMS activity on Foxtail grass in the presence of surfactant. 

Comparisons similar to those outlined in Equations 28-31 were likewise undertaken for the remaining cases (Foxtail with Tween 80 present Wild Mustard with and without Tween 80 present Cheat Grass without Tween 80 present). The statistical parameters for the final best-fit Hansch correlations for each case are listed in Table IX. 

On the basis of the statistical data in Table IX, the parent TFMS herbicide is obviously more correctly placed with the 4-substituted series members than with the 3-TFMS compounds. Finally, Table X lists, for comparative purposes, the best-fitting equational and statistical parameters for Hansch correlations of the herbicidal data for 4-substituted series members in which the parent compound has been included. These equations should be compared with those in Table XI. 

Hansch correlations as described above. In performing the correlations, appropriate w and t/ values were selected from Table VI the latter values were used for data gathered in the presence of 0.1% Tween 80. Both tr and t/ are calculated relative to log PH = 3.05 for the parent compound in the absence of surfactant (see Equation 6). Thus, a given TFMS compound in the presence of Tween 80 might be thought of as a new member of the similarly substituted TFMS series characterized by somewhat different partitioning properties than it originally exhibited in the... 

The results in Table XII show that Hansch correlations carried out on pooled herbicidal data gathered in the presence and absence of Tween 80 for a given classification of TFMS compounds acting on a particular weed type produce significantly poorer ultimate structure—activity relationships than those which are obtained if the activity data gathered in the presence and absence of surfactant are fitted separately. For both... 

C. Silipo, C. Hansch, Correlation analysis. Its application to the structure-activity relationship of triazines inhibiting dihydrofolate reductase, J. Am. Chem. Soc. 1975,... 

Historically Hansch correlated the Hammett o constant and log (n-octanol-water partition coefficient) of phenoxyacetic acids with their plant growth regulator activity producing equation 1 ... 

Similar concepts are important in medicinal chemistry, in which the properties of a proposed drug are predicted on the basis of the effects of a series of known drugs. A leading researcher in this area is Corwin Hansch, for whom the Hansch correlation is named. For a discussion of quantitative structure—activity relationships, see Hansch, C. Leo, A. Exploring QSAR Fundamentals and Applications in Chemistry and Biology American Chemical Society Washington, DC, 1995. 

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