Many people in the world struggle with cancer or bacterial, parasitic, viral, Alzheimer's and other diseases. Therefore, many scientists seek new, more effective, more selective and less toxic drugs. Acridine/acridone derivatives constitute a class of compounds with a broad spectrum of biological activity and are of great interest to scientists. To date, many acridine/acridone analogues have been obtained, which, inter alia, exhibit antitumour (e.g., (1–5)), antimicrobial (e.g., (59)), and antiviral (e.g., (61)) activities and are applicable in the treatment of Alzheimer's disease (e.g., (26)). However, in many cases, their clinical application is limited and excluded because of side effects. In this survey, we describe acridine and acridone derivatives reported since 2013, methods of their synthesis and their potential clinical applications.

Tacrine is a potent inhibitor of cholinesterases (acetylcholinesterase and butyrylcholinesterase) that shows limiting clinical application by liver toxicity. In spite of this, analogues of tacrine are considered as a model inhibitor of cholinesterases in the therapy of Alzheimer’s disease. The interest in these compounds is mainly related to a high variety of their structure and biological properties. In the present review, we have described the role of cholinergic transmission and treatment strategies in Alzheimer’s disease as well as the synthesis and biological activity of several recently developed classes of multifunctional tacrine analogues and hybrids, which consist of a new paradigm to treat Alzheimer’s disease. We have also reported potential of these analogues in the treatment of Alzheimer’s diseases in various experimental systems.