Privileged structures as leads in medicinal chemistry

Among the strategies that can lead to the discovery of new drugs, the identification and use of privileged structures, molecular fragments that are able to interact with more than one target, gained particular attention, in an attempt to find new drugs in a shorter time with respect to other strategies. These structures, that have been identified mainly by empirical observations, can target only a given protein family, or can be able to interact with more, unrelated targets. This review deals with structures not covered in recent papers on this topic, and emphasizes the importance of understanding the structure-target relationships, that confer the privileged status.