Hybrids: a new paradigm to treat Alzheimer's disease.

Alzheimer's disease (AD) is a complex neurodegenerative condition with several target proteins contributing to its etiology. With 35.6 million cases worldwide documented in 2011, AD constitutes a devastating health, political, economic, and social problem for all nations. The cases are expected to increase beyond 107 million in 2050; unless an advanced therapy having a capability to delay the disease progression is developed. The curative paradigm of one-compound one-target that has been followed so far has not reached the desired mark. The research focus moved towards single molecule targeting two or more pathogenic mechanisms involved in neuronal death. Over the last few years, medicinal chemists have been paying attention to the design and synthesis of the hybrid molecules that are comprised of two pharmacophores from well-established chemical scaffolds endowed with requisite biological activities in a single entity. The hybrid-based approach has grown to be a central point in the medicinal chemistry field. Various important pharmacophores used for AD have been combined with selected biologically active molecules to get homo- and heterodimers with improved efficacy with additional supplementary actions. This review summarizes the pathogenesis of AD and various progress in the design of hybrid molecules based on the one-compound-various targets paradigm for AD therapy.