Preferred chemical structures for therapeutic activities

Certain functional groups are biologically active and confer this activity with a highly significant frequency on the molecules to which they can be grafted. For example, alcohols and phenols have sedative and antiseptic effects respectively, while the bis-(2-chloroethylamine) motif, found in several anticancer agents such as chlorambucil, is responsible for their alkylating properties. Similarly, cyclic skeletons, such as the cyclopentanoperhydrophenantric linkage, are a common motif in steroids with hormonal, anti-inflammatory, diuretic and cardiostimulant activity.

Specific structural elements, grouped together under the term pharmacophore, are recognized by a target, receptor or enzyme, and are responsible for biological activity. The substituents attached to these pharmacophores only act to modulate the activity and/or modify the pharmacokinetics of the active ingredients: increased duration of action, reduced toxicity, improved bioavailability, increased stability, etc.

Qualitative structure-activity relationships, originally established empirically on the basis of the analysis of active ingredient formulas, have been consolidated and developed through molecular modeling studies, to become indispensable in the design of new drugs (drug design).

The aim of this article is to teach you how to recognize the main structural motifs responsible for pharmacological activity, based on the active ingredients characteristic of the main drug families currently on the market. Secondly, the fundamental mechanisms of action of each therapeutic class are discussed in relation to the skeletons of the active substances.