The Prediction of Biological Activity Using Molecular Connectivity Indices.

A highly influential paper by Randic entitled On characterization of molecular branching appeared in the Journal of the American Chemical Society. In this paper a new topological index was introduced which has since become known as the molecular connectivity index. Topological indices Tis are graph-theoretical invariants which are employed extensively as matheamtical descriptors for a wide range of molecular species. They have been used mainly for the purpose of correlating the properties of molecular species with their topological structure. The molecular connectivity index was originally put forward with the aim of characterizing the branching in alkane species, but more recently has been shown to have numerous applications in both the physical and biological sciences. In this review we shall focus on the use of the index in the more biologically oriented sciences, such as pharmacology and toxicology. In particular, we shall discuss the prediction of biological activity in chemical species by means of this index. The molecular connectivity index as originally presented by Randic was designed to parallel the ordering obtained for sets of isomeric alkane molecules based on their physicochemical properties.