STRUCTURE-PROPERTY-ACTIVITY MODELING USING WEIGHTED PATH NUMBERS

Dragan Amiæ,a Bono Lusiæ,b Sonja Nikoliæ,b and Nenad Trinajstiæb

aFaculty of Agriculture, The Josip Juraj Strossmayer University,
HR-31001 Osijek, Croatia;
bThe Rugjer Boskoviæ Institute, HR-10001 Zagreb, Croatia


All descriptors are equal, but some are more equal than others.
Milan Randiæ

There are more than 3000 empirical and theoretical molecular descriptors available for the use in the structure-property-activity modeling [1]. In spite of this large number of descriptors, there are still lacking good descriptors for many molecular properties [2]. It is especially difficult to unearth good theoretical descriptors to handle diverse heterosystems. This was motivation for the present study: The aim was to investigate the use of weighted path numbers as molecular descriptors in structure-property-activity studies. The use of path numbers was already advocated many years ago by Platt [3] and more recently by Randiæ [4,5].

Weighted path numbers have been used as follows. Instead of using prescribed weights for paths6 we optimized the weights so that the standard error of estimate in regression analysis is as small as possible. Water solubilites and toxicites of aliphatic alcohols are considered in this study. Models we obtained possess statistical characteristics superior to empirical and theoretical models reported in the literature. This result supports further structure-property-activity studies based on weighted path numbers.
 

1. R. Todeschini and V. Consonni, Handbook of Molecular Descriptors, Wiley-VCH, Weinheim, 2000.

2. J. Devillers and A. T. Balaban, Eds., Topological Indices and Related Descriptors in QSAR and QSPR, Gordon & Breach Sci. Publ., Amsterdam, 1999.

3. J. R. Platt, Influence of Neighbor Bonds on Additive Bond Properties in Paraffins, J. Chem. Phys. 1947, 15, 419-420.

4. M. Randiæ, Linear Combinations of Path Numbers as Molecular Descriptors, New J. Chem. 1997, 21, 945-951.

5. M. Randiæ and S.C. Basak, Optimal Molecular Descriptors Based on Weighted Path Numbers, J. Chem. Inf. Comput. Sci. 1999, 39, 261-266.

6. N. Trinajstiæ, Chemical Graph Theory, second revised edition, CRC, Boca Raton, FL, 1992.