Spirocyclohexadienones as an Uncommon Scaffold for Acetylcholinesterase Inhibitory Activity

Stem Cells and Natural Agents in the Management of Neurodegenerative Diseases: A New Approach

Neurodegenerative diseases refer to a group of neurological disorders as a consequence of various destructive illnesses, that predominantly impact neurons in the central nervous system, resulting in impairments in certain brain functions. Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, and other neurodegenerative disorders represent a major risk to human health. In order to optimize structural and functional recovery, reconstructive methods integrate many approaches now, to address the complex and multivariate pathophysiology of neurodegenerative disorders. Stem cells, with their unique property of regeneration, offer new possibilities in regenerative and reconstructive medicine. Concurrently, there is an important role for natural products in controlling many health sufferings and they can delay or even prevent the onset of various diseases. In addition, due to their therapeutic properties, they have been used as neuroprotective agents to treat neurodegenerative disorders. After decades of intensive research, scientists made advances in treating these disorders so far, but current therapies are still not capable of preventing the illnesses from progressing. Therefore, in this review, we focused on a new perspective combining stem cells and natural products as an innovative therapy option in the management of neurodegenerative diseases.

Aaptamine - a dual acetyl - and butyrylcholinesterase inhibitor as potential anti-Alzheimer's disease agent

CONTEXT

Alzheimer's disease (AD) is a neurodegenerative disorder that affects millions of people worldwide. Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) are promising therapeutic targets for AD.

OBJECTIVE

To evaluate the inhibitory effects of aaptamine on two cholinesterases and investigate the in vivo therapeutic effect on AD in a zebrafish model.

MATERIALS AND METHODS

Aaptamine was isolated from the sponge Aaptos suberitoides Brøndsted (Suberitidae). Enzyme inhibition, kinetic analysis, surface plasmon resonance (SPR) and molecular docking assays were used to determine its inhibitory effect on AChE and BuChE in vitro. Zebrafish were divided into six groups: control, model, 8 μM donepezil, 5 , 10  and 20 μM aaptamine. After three days of drug treatment, the behaviour assay was performed.

RESULTS

The IC₅₀ values of aaptamine towards AChE and BuChE were 16.0 and 4.6 μM. And aaptamine directly inhibited the two cholinesterases in the mixed inhibition type, with K_i values of 6.96 ± 0.04 and 6.35 ± 0.02 μM, with K_d values of 87.6 and 10.7 μM. Besides, aaptamine interacts with the crucial anionic sites of AChE and BuChE. In vivo studies indicated that the dyskinesia recovery rates of 5 , 10  and 20 μM aaptamine group were 34.8, 58.8 and 60.0%, respectively, and that of donepezil was 63.7%.

DISCUSSION AND CONCLUSIONS

Aaptamine showed great potential to exert its anti-AD effects by directly inhibiting the activities of AChE and BuChE. Therefore, this study identified a novel medicinal application of aaptamine and provided a new structural scaffold for the development of anti-AD drugs.

Spirocyclohexadienone-Type Neolignans with Neuroprotective and Neurite Outgrowth Enhancing Activities from Magnolia liliiflora

Three rare spirocyclohexadienone-type neolignans, magnoflorins A-C (1-3), and three known analogs (4-6), were isolated from the leaves of Magnolia liliiflora. Magnoflorin D (4) was obtained from natural resources for the first time. The chemical structures and absolute configurations of 1-4 were elucidated through detailed analysis of HR-ESI-MS, IR, ¹ H, ¹³ C, and 2D NMR, and ECD experiments. The absolute configuration of 5 were characterized by X-ray crystallography in present study. Moreover, compounds 4 and 5 displayed moderate neuroprotective activity against corticosterone-induced PC12 cells injury at 20 μM with cell viability of 71.5±0.99 % and 73.0±1.42 %, respectively, compared to the model group with 60.83±0.93 %. Compound 6 could enhance neurite outgrowth of nerve growth factor (NGF)-induced PC12 cells at 10 μM with the differentiation rate of 11.98 %, compared with 20.49 % of 50 ng/ml NGF.

Spirocyclic derivatives as antioxidants: a review

In recent years, spiro compounds have attracted significant interest in medicinal chemistry due to their numerous biological activities attributed primarily to their versatility and structural similarity to important pharmacophore centers. Currently, the development of drugs with potential antioxidant activities is of great importance since numerous investigations have shown that oxidative stress is involved in the development and progression of numerous diseases such as cancer, senile cataracts, kidney failure, diabetes, high blood pressure, cirrhosis, and neurodegenerative diseases, among others. This article provides an overview of the synthesis and various antioxidant activities found in naturally occurring and synthetic spiro compounds. Among the antioxidant activities reviewed are DPPH, ABTS, FRAP, anti-LPO, superoxide, xanthine oxidase, peroxide, hydroxyl, and nitric oxide tests, among others. Molecules that presented best results for these tests were spiro compounds G14, C12, D41, C18, C15, D5, D11, E1, and C14. In general, most active compounds are characterized for having at least one oxygen atom; an important number of them (around 35%) are phenolic compounds, and in molecules where this functional group was absent, aryl ethers and nitrogen-containing functional groups such as amine and amides could be found. Recent advances in the antioxidant activity profiles of spiro compounds have shown that they have a significant position in discovering drugs with potential antioxidant activities.

Exploring the efficacy of natural products in alleviating Alzheimer's disease

Alzheimer’s disease (hereafter AD) is a progressive neurodegenerative disorder that affects the central nervous system. There are multiple factors that cause AD, viz., accumulation of extracellular Amyloid-beta 42 plaques, intracellular hyper-phosphorylated Tau tangles, generation of reactive oxygen species due to mitochondrial dysfunction and genetic mutations. The plaques and tau tangles trigger aberrant signaling, which eventually cause cell death of the neurons. As a result, there is shrinkage of brain, cognitive defects, behavioral and psychological problems. To date, there is no direct cure for AD. Thus, scientists have been testing various strategies like screening for the small inhibitor molecule library or natural products that may block or prevent onset of AD. Historically, natural products have been used in many cultures for the treatment of various diseases. The research on natural products have gained importance as the active compounds extracted from them have medicinal values with reduced side effects, and they are bioavailable. The natural products may target the proteins or members of signaling pathways that get altered in specific diseases. Many natural products are being tested in various animal model systems for their role as a potential therapeutic target for AD, and to address questions about how these natural products can rescue AD or other neurodegenerative disorders. Some of these products are in clinical trials and results are promising because of their neuroprotective, anti-inflammatory, antioxidant, anti-amyloidogenic, anticholinesterase activities and easy availability. This review summarizes the use of animal model systems to identify natural products, which may serve as potential therapeutic targets for AD.