Recent Advances in the Synthesis of Tacrine Derivatives as Multifunctional Agents for Alzheimer's Disease

: Alzheimer's is a neurodegenerative pathology. The first therapeutic strategy for treating AD was mainly acetylcholinesterase inhibitors (AChEIs). One of them is Tacrine, a linear tricyclic compound that occupies an important place in treating this disease with its pharmacophore properties. In this regard, the development of tacrine-analogs more efficient and safe with new measures and investigations has drawn immense attention. Various structural modifications of Tacrine have been carried out on different parts. Mainly some change in the ring structure of Tacrine or by connecting the amino group with different hybrids based on natural or synthetic compounds and drugs already in existence. These tacrine congeners have considerable potential for developing new drugs for the treatment of Alzheimer's disease. Therefore, this review presents an overview of the essential structural modifications in tacrine rings based on the current trends reported in recent decades towards using natural products and synthetic analogs as a source of new anti-Alzheimer drugs.