A Z-weighted information content index
James W. King · International Journal of Quantum Chemistry · 2009
In the study of the effects of chemical structure variations on pharmacological activity, the information content of a molecule may be expressed by derived numeric indices. Any one of these may be used as a parametric descriptor in correlation trials. In a series of azabutadiene sensory irritants, two new information theoretic indices, the Modified Information Content (MIC) Index and the Z-Modified Information Content (ZMIC) Index were used to derive correlation equations relating these indices to respiratory inhibition in mice. The MIC Index uses the atomic weight of constituent atoms of a compound to weigh the individual terms of the Information Content (IC) Index prior to summation; the zmic Index uses the atomic number (Z) to weigh the terms. Linear regression trials indicated that the unmodified IC Index and the related Structural Information Content (SIC) Index did not explain the variance in the pharmacological data. However, increasingly adequate correlations were obtained with the MIC Index. followed by molecular weight and then the ZMIC Index. The latter appears to give some topographical character to what would otherwise be a topological index and has the potential for enhancing the usefulness of these methods.