A series of N-benzylated (pyrrolidin-2-one)/(imidazolidin-2-one) derivatives were synthesized and evaluated for anti-Alzheimer's activity. The analogs were designed and synthesized on the basis of lead compound donepezil, which is currently prescribed as a major drug for the management of mild to severe Alzheimer's disease. Considering the structure activity relationship (SAR) of the lead compound, we first replaced the 5,6-dimethoxy-1-indanone moiety with N-benzylated (pyrrolidin-2-one)/(imidazolidin-2-one) (head) without depriving the key functionality interactions like carbonyl and dimethoxyphenyl and second substituted the spacer linkage (tail) in donepezil. The newly synthesized compounds were characterized by structural conformity and purity using various techniques. The compounds were then subjected to in vivo (behavioral studies) and in vitro (biochemical assays) evaluation using appropriate animal models against the standard drug. Compounds 3-(4-(4-fluorobenzoyl)-piperidin-1-yl)-1-(4-methoxybenzyl)-pyrrolidin-2-one (10b) and 1-(3,4-dimethoxybenzyl)-3-((1-(2-(trifluoromethyl)-benzyl)-piperidin-4-yl)-methyl)-imidazolidin-2-one (18c) displayed an excellent anti-Alzheimer's profile, while the rest of the compounds showed satisfactory results in comparison to donepezil.

: 1, 8- Naphthyridine nucleus belongs to significant nitrogen-containing heterocyclic compounds which have garnered the interest of researchers due to its versatile biological activities. It is known to be used as an antimicrobial, anti-psychotic, anti-depressant, anti-convulsant, anti-Alzheimer’s, anti-cancer, analgesic, anti-inflammatory, antioxidant, anti-viral, anti-hypertensive, anti-malarial, pesticides, anti-platelets, and CB2 receptor agonist, etc. The present review highlights the framework of biological properties of synthesized 1, 8-naphthyridine derivatives developed by various research groups across the globe.

Background: Alzheimer’s disease (AD) is an irreversible, progressive and very complex brain disorder. There is still uncertainty around the etiology of AD, but a few hallmarks like an aggregation of tau proteins, amyloid-β plaques, oxidative stress, low level of choline in the brain etc. play significant roles. Objective: In the present work, we aim to evaluate the recent progress in the development of small organic molecules containing heterocycles like thiazole, pyridines, dihydropyridines, piperidines, pyrrolidines, pyrazoles, quinolines etc. as anti-Alzheimer’s agents. Method: Several databases of different journal publications SciFinder, Science Direct, Bentham Science, and Pubmed were searched for relevant articles and reviewed for the present work. Results: Several research groups are actively working on these heterocycle-based compounds as potent single-target inhibitors. Most of the analogues have been evaluated for their cholinesterase (acetylcholinesterase and butyrylcholinesterase) inhibition potential. Several studies have also reported the inhibitory potential of the analogues against MAO-A, MAO-B and BACE-1 enzymes. But nowadays instead of targeting one enzyme or protein, more than one heterocycle ring is being joined to develop MTDLs (multi-target-directed ligands). Especially, donepezil has become the focal point of anti-AD drug discovery projects. Several research groups have reported various donepezil-based analogues by replacing/modifying its various ring systems like indanone, piperidine or the methylene linker. Conclusion: Small molecules with nitrogen-containing heterocycles have become the core of drug discovery efforts for AD. With the increasing prominence of the MTDL approach, several new ligands are being discovered as potent anti-AD agents.

Background: ABSTRACT: Background: 8-Phenyltheophylline derivatives exhibit prophylactic effects at a specific dose but do not produce the cardiovascular or emetic side effects associated with xanthines, thereby exhibiting unique characteristics of potential therapeutic importance. Methods: Novel series of 8-(proline/pyrazole)-substituted xanthine analogs has been synthesized. The affinity and selectivity of compounds to adenosine receptors have been assessed by radioligand binding studies. The synthesized compounds also showed good bronchospasmolytic properties (increased onset of bronchospasm; decreased duration of jerks) with 100% survival of animals in comparison to the standard drug. Besides, compound 8f & 9f showed good binding affinity in comparison to other synthesized compounds in the micromolar range. Results: The maximum binding affinity of these compounds was observed for A2B receptors, which is ~ 7 or 10 times higher as compared to A1, A2A and A3 receptors. The newly synthesized derivatives 8f, 9a-f, 17g-m, and 18g-m displayed significant protection against histamine aerosol induced bronchospasm in guinea pigs. Conclusion: Newly synthesized proline/pyrazole based xanthines compounds showed a satisfactory binding affinity for adenosine receptor subtypes. Replacement or variation of substituted proline ring with substituted pyrazole scaffold at 8thposition of xanthine moiety resulted in the reduction of adenosine binding affinity and bronchospasmolytic effects.

No abstract