Edge adjacency relationships and molecular topographic descriptors. Definition and QSAR applications

Edge adjacency relationships in molecular graphs have been used to define a new topographic index. The novel index is calculated considering molecules as weighted graphs, where the elements of edges set are substituted by the bond orders between connected atoms in the molecule. Good linear correlations were found between molar refractivity of alkanes and the proposed epsilon (rho) index. The applicability of the novel index in QSAR studies was evaluated by using a data of pharmacokinetic properties for a series of amphetamine derivatives. The results obtained were statistical and pharmacologically significant. Special interest is dedicated to discrimination of isomers, including heteroatom's differentiation and conformational isomerism.