Proton-ligand formation constants of salicylhydroxamic acids (SHA) and their nuclear substituted derivatives have been estimated topologically using the normalized Wiener index, referred to as mean square Wiener index (Wms). Regression analysis of the data indicates that Wms can be used successfully for estimating and monitoring proton-ligand formation constants.

The paper gives a brief account of the recently introduced Szeged index (Sz). Using this index antitubercular activities of N-2,4-difluorophenyl quinolones are subjected to quantitative structure-activity relationship analysis. The potential of Sz related to the Wiener index (W) is critically discussed. In addition, Huckel molecular orbital energies:E_HOMO,E_LUMO andE_total were also used for comparing and modelling antitubercular activities of the quinolones. The results, based on univariate as well as multivariate regressions, have shown that W, S_Z andE_total give better results and that the correlations improve in multivariate regression analyses.