Pharmacology of Alzheimer's disease: appraisal and prospects

Role of multi-targeted bioactive natural molecules and their derivatives in the treatment of Alzheimer's disease: an insight into structure-activity relationship

Alzheimer's disease (AD) is a complex neurodegenerative disorder involving cognitive dysfunction like short-term memory and behavioral changes as the disease progresses due to other unaltered physiological factors. The solution for this problem is Multi-targeted Drugs (MTDs), which can affect multiple determinants to realize the multifunctional effects. Acetylcholinesterase (AChE) inhibitors donepezil, rivastigmine, galantamine, and N-methyl-D-aspartate (NMDA) receptor antagonist memantine are FDA-approved drugs used to treat AD symptomatically. The key objective of this review is to understand multitargeted bioactive natural molecules that could be considered as leads for further development as effective drugs for treating AD, along with understanding its pharmacology and structure-activity relationship (SAR). Understanding the molecular mechanism of the AD pathophysiology, the role of existing drugs, treatment of AD via amyloid beta (Aβ) plaque, and neurofibrillary tangle (NFT) inhibition by natural bioactive molecules were also discussed in the review. The current quest and recent advancements with natural bioactive compounds like physostigmine, resveratrol, curcumin, and catechins, along with the study of in silico SAR, were reported in the present study. This review summarises the structural properties required for bioactive natural molecules to show anti-Alzheimer's activity by emphasizing on SAR of several bioactive natural molecules targeting various AD pathologies, their key molecular interactions that are critical for target specificity, their role as multitargeted ligands, used with adjunctive therapy for AD followed by related US patents granted recently. This article highlights the significance of the structural features of natural bioactive molecules in the treatment of AD and establishes a connection between them.Communicated by Ramaswamy H. Sarma.

Pharmacological characterization of some selected 4,5-dihydro-4-oxo-1,2,4-triazolo[1,5-a]quinoxaline-2-carboxylates and 3-hydroxyquinazoline-2,4-diones as (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)-propionic acid receptor antagonists

In the present study, some selected, previously reported 4,5-dihydro-4-oxo-1,2,4-triazolo[1,5-a]quinoxaline-2-carboxylates (TQXs) and 3-hydroxy-quinazoline-2,4-diones (QZs), were evaluated for their affinity at the (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)-propionic acid (AMPA) receptor in the [(3)H]-6-cyano-7-nitroquinoxaline-2,3-dione ([(3)H]-CNQX) binding assay. Electrophysiological experiments were performed in oocytes expressing rat homomeric GluR3 subunits in order to assess the pharmacological profile of the tested compounds. The binding data, together with those regarding the functional activity, confirmed that most of the TQXs and QZs reported herein are potent AMPA receptor antagonists. When tested for their ability to prevent sound-induced seizures in DBA/2 mice, some of these derivatives showed anticonvulsant properties.

Disease-modifying drugs and Parkinson's disease

Symptomatic medications, l-Dopa and dopaminergic agents, remain the only clinically pertinent pharmacological treatment proven effective and available for the large population of patients with Parkinson's disease. The challenge for the pharmaceutical industry is to develop disease-modifying drugs which could arrest, delay or at least oppose the progression of the specific pathogenic processes underlying Parkinson's disease. The purpose of this review, based on recent biological and genetic data to be validated with appropriate animal models, was to re-examine the putative neuroprotective agents in Parkinson's disease and discuss the development of new strategies with the ultimate goal of demonstrating neurocytoprotective activity in this neurodegenerative disease. Since guidelines for research on neurocytoprotective drugs remain to be written, innovation will be the key to success of future clinical trials. It is reasonable to expect that future advances in our understanding of the pathogenic processes of Parkinson's disease will open the way to new perspectives for the treatment of other neurodegenerative diseases.

Structural Investigation of the 7-Chloro-3-hydroxy-1H-quinazoline-2,4-dione Scaffold to Obtain AMPA and Kainate Receptor Selective Antagonists. Synthesis, Pharmacological, and Molecular Modeling Studies

In this paper, the study of new 7-chloro-3-hydroxy-1H-quinazoline-2,4-dione derivatives, designed as AMPA and kainate (KA) receptor antagonists, is reported. Some derivatives bear different carboxy-containing alkyl chains on the 3-hydroxy group, while various heterocyclic rings or amide moieties are present at the 6-position of other compounds. Binding data at Gly/NMDA, AMPA, and high-affinity KA receptors showed that the presence of the free 3-hydroxy group is of paramount importance for a good affinity at all three investigated receptors, while introduction of some 6-heterocyclic moieties yielded AMPA-selective antagonists. The most significant result was the finding of the 6-(2-carboxybenzoylamino)-3-hydroxy-1H-quinazolin-2,4-dione 12, which possesses good affinity for high-affinity and low-affinity KA receptors (Ki=0.62 microM and 1.6 microM, respectively), as well as good selectivity. To rationalize the trend of affinities of the reported derivatives, an intensive molecular modeling study was carried out by docking compounds to models of the Gly/NMDA, AMPA, and KA receptors.

Gonadotropins: potential targets for preventive and therapeutic interventions in Alzheimer’s disease

Increased prevalence of Alzheimer’s disease (AD) in women has led to an interest in the role of hormonal changes in the neurodegenerative process. In particular, research has been directed towards investigating the effect of changes in sex hormone levels following reproductive senescence. Clinical trials of hormone-replacement therapy for the prevention of AD are proving contentious, and considerably more research is necessary before the benefit of the hormone replacement strategy can be ascertained. However, evidence is now emerging to support the notion that increased gonadotropin levels may confer an increased risk of AD. Gonadotropins have been implicated in the metabolism of β-amyloid, a key protein that is central to the pathogenesis of AD. Gonadotropin reduction represents a promising new target for therapeutic intervention in AD and, potentially, dementia in general. In this review, the authors discuss the therapeutic and preventive potential of gonadotropin-reducing agents in the management of AD.