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• Recent developments of nitrogen-containing heterocyclic compounds as antidepressant have been discussed. • The antidepressant profile of the potent derivatives along with structural insights is presented. • The SAR studies of recently developed compounds are discussed in details for providing key structural features. • The lead compounds for further development are identified and discussed in the perspective part of this review. According to the World Health Organization (WHO), depression is a common mental disorder and includes complex interaction between social and psychological behaviour affecting 264 million people worldwide. The review aims to highlight the role and importance of nitrogen-based heterocyclics in the development of antidepressant compounds. Many research groups have attempted to design drug candidates capable of binding within the receptors. The commonest drug design strategy includes the incorporation of different structural features widely recognized as an antidepressant in the synthesized derivatives to enhance their CNS antidepressant effects. In this review, we have shed light on nitrogenous heterocyclic moieties such as quinazoline, pyridine, pyrimidine, pyrrolidine, imidazole, pyrazole, piperidine, oxadiazole, benzimidazole, benzothiazole, piperazine, triazine, purine, benzoxazole, and isoxazole as core nucleus and/or in combination as an antidepressant compound. These molecules with different structural features were noted to exert their antidepressant effects by multiple mechanisms viz., selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase (MAO) inhibitors, and Catechol- O -methyltransferase (COMT) inhibitors. The review focuses on the selection of these heterocyclic moieties for the further design and development of promising antidepressants by taking a clue from the earlier reported potent antidepressant compounds or from the marketed products. The results have been correlated with their structural activity relationship (SAR) to identify the substituents for the potency and selectivity within the receptors. This review might help the researchers working in the antidepressant field to develop more novel molecules that could fill the gap by improving potency and reducing toxicity. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hybridization drug design strategies with rationale to obtain multi target directed ligands (MTDLs) as anti-Alzheimer drugs. • The review covers SAR studies for further development of coumarin-hybrids as therapeutic agents for the Alzheimer's disease (AD). • It provides an overview of research work carried out on di and tri-hybridized coumarin conjugates during 2010–2020. • Chemical structure and biochemical targets of naturally occurring coumarin derivatives with anti-AD properties. • Patents granted to coumarin derivatives for AD treatment. Alzheimer's disease (AD) is a major progressive and perplexing cortical degenerative disease of the brain in the elderly. It contributes to a significant socioeconomic burden on patients, families, and care providers in comparison to cancer, cardiovascular diseases, and stroke in general. Recently, a hybridized approach based on multi-target directed ligands (MTDLs) has received considerable attention to develop therapeutic agents for AD which act at multiple targets. Approximately 20% of the drugs approved in the past couple of years were developed using the same strategy and thus it seems to be the right approach to develop AD therapy. The comprehensive and updated review on coumarin hybrids as MTDLs in AD therapy is compiled using several electronic databases such as Scopus, Google Scholar, SciFinder, Mendeley, and PubMed. The research studies published on coumarin hybrids in the last decade (2010- 2020) have been covered in this review article. This updated review highlights the importance of coupling (hybridization) coumarin scaffold with other bioactive pharmacophores to develop MTDLs for AD therapy. It also covers the patents granted to coumarin derivatives for AD treatment, natural products containing coumarin scaffold with anti-Alzheimer spectrum, the rationale for coupling pharmacophore fragments, detailed structure activity relationship (SAR), and molecular docking studies. The most potent and promising hybrid compounds have also been identified for further development of AD drugs. Authors are of the opinion that hybridization strategy would soon yield drug candidates for the treatment of AD. [ABSTRACT FROM AUTHOR]