In vivo Evaluation of a Newly Synthesized Acetylcholinesterase Inhibitor in a Transgenic Drosophila Model of Alzheimer's Disease

Using Drosophila amyloid toxicity models to study Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia and is characterised by a progressive loss of neurons, which manifests as gradual memory decline, followed by cognitive loss. Despite the significant progress in identifying novel biomarkers and understanding the prodromal pathology and symptomatology, AD remains a significant unmet clinical need. Lecanemab and aducanumab, the only Food and Drug Administration approved drugs to exhibit some disease-modifying clinical efficacy, target Aβ amyloid, underscoring the importance of this protein in disease aetiology. Nevertheless, in the absence of a definitive cure, the utilisation of preclinical models remains imperative for the identification of novel therapeutic targets and the evaluation of potential therapeutic agents. Drosophila melanogaster is a model system that can be used as a research tool to investigate neurodegeneration and therapeutic interventions. The short lifespan, low price and ease of husbandry/rearing make Drosophila an advantageous model organism from a practical perspective. However, it is the highly conserved genome and similarity of Drosophila and human neurobiology which make flies a powerful tool to investigate neurodegenerative mechanisms. In addition, the ease of transgenic modifications allows for early proof of principle studies for future therapeutic approaches in neurodegenerative research. This mini review will specifically focus on utilising Drosophila as an in vivo model of amyloid toxicity in AD.

Green synthesis, biological and molecular docking of some novel sulfonamide thiadiazole derivatives as potential insecticidal against Spodoptera littoralis

Although crop plants provide the majority of human food, pests and insects frequently cause huge economic losses. In order to develop innovative insecticidal compounds with low toxicity and a positive environmental impact, we developed new N-(4-sulfamoylphenyl)-1,3,4-thiadiazole-2-carboxamide derivatives (2-12). With the use of spectroscopic techniques and elemental data, the chemical structure of these new compounds was meticulously clarified. The toxicological and biological effects of the synthesized compound of the cotton leafworm Spodoptera littoralis (Boisduval, 1833) under laboratory conditions were also investigated. Regarding the determined LC50 values, compounds 3, 7, 8, and 10 showed the most potent toxic effect with LC50 values of 29.60, 30.06, 27.65 and 29.01 ppm, respectively. A molecular docking investigation of twelve synthetic compounds (from compound 2 to compound 12) was performed against AChE (Acetylcholinesterase). There was a wide range of binding affinities shown by these compounds. This work suggests that these substances may have insecticidal and AChE inhibitory properties, and it may be possible to further explore them in the process of creating pesticides that target AChE.

Effect of donepezil hydrochloride on the transgenic Drosophila expressing human Aβ-42

CONCLUSION

The results suggest that donepezil hydrochloride is potent enough to reduce the AD symptoms being mimicked in transgenic flies.

Development of p-Tau Differentiated Cell Model of Alzheimer's Disease to Screen Novel Acetylcholinesterase Inhibitors

Alzheimer's disease (AD) is characterized by an initial accumulation of amyloid plaques and neurofibrillary tangles, along with the depletion of cholinergic markers. The currently available therapies for AD do not present any disease-modifying effects, with the available in vitro platforms to study either AD drug candidates or basic biology not fully recapitulating the main features of the disease or being extremely costly, such as iPSC-derived neurons. In the present work, we developed and validated a novel cell-based AD model featuring Tau hyperphosphorylation and degenerative neuronal morphology. Using the model, we evaluated the efficacy of three different groups of newly synthesized acetylcholinesterase (AChE) inhibitors, along with a new dual acetylcholinesterase/glycogen synthase kinase 3 inhibitor, as potential AD treatment on differentiated SH-SY5Y cells treated with glyceraldehyde to induce Tau hyperphosphorylation, and subsequently neurite degeneration and cell death. Testing of such compounds on the newly developed model revealed an overall improvement of the induced defects by inhibition of AChE alone, showing a reduction of S396 aberrant phosphorylation along with a moderate amelioration of the neuron-like morphology. Finally, simultaneous AChE/GSK3 inhibition further enhanced the limited effects observed by AChE inhibition alone, resulting in an improvement of all the key parameters, such as cell viability, morphology, and Tau abnormal phosphorylation.

Comparative study of rivastigmine and galantamine on the transgenic Drosophila model of Alzheimer's disease

Alzheimer's Disease (AD) is characterized as a progressive neurodegenerative disease most commonly associated with memory deficits and cognitive decline. The formation of amyloid plaques and neurofibrillary tangles are important pathological markers of AD. The accumulation of amyloid plaques and neurofibrillary tangles leads to the loss of neurons including the cholinergic neurons thus decreasing the levels of acetylcholine (a neurotransmitter). To reduce the AD symptoms cholinesterase inhibitors are widely used to decrease the hydrolysis of acetylcholine released from presynaptic neurons. In the present study we have studied the effect of rivastigmine and galantamine (commonly used cholinesterase inhibitors) on the transgenic Drosophila model of AD expressing human Aβ-42 in the neurons. The effect of similar doses of rivastigmine and galantamine (i.e. 0.1,1 and 10 ​mM) was studied on the climbing ability, lifespan, oxidative stress markers, caspase 9 and 3, acetylcholinesterase activity and on the formation of Aβ-42 aggregates. The results suggest that the rivastigmine is more potent in reducing the oxidative stress and improving climbing ability of AD flies. Both the drugs were found to be effective in increasing the lifespan of AD flies. Galantamine was found to be a more potent inhibitor of acetylcholinesterase compared to rivastigmine. Galantamine prevents the formation of Aβ-42 aggregates more effectively compared to rivastigmine.

Identification of a Hydrogen-Sulfide-Releasing Isochroman-4-One Hybrid as a Cardioprotective Candidate for the Treatment of Cardiac Hypertrophy

Cardiac pathological hypertrophy is associated with undesirable epigenetic changes and causes maladaptive cardiac remodeling and heart failure, leading to high mortality rates. Specific drugs for the treatment of cardiac hypertrophy are still in urgent need. In the present study, a hydrogen-sulfide-releasing hybrid 13-E was designed and synthesized by appending p-hydroxythiobenzamide (TBZ), an H₂S-releasing donor, to an analog of our previously discovered cardioprotective natural product XJP, 7,8-dihydroxy-3-methyl-isochromanone-4. This hybrid 13-E exhibited excellent H₂S-generating ability and low cellular toxicity. The 13-E protected against cardiomyocyte hypertrophy In Vitro and reduced the induction of Anp and Bnp. More importantly, 13-E could reduce TAC-induced cardiac hypertrophy In Vivo, alleviate cardiac interstitial fibrosis and restore cardiac function. Unbiased transcriptomic analysis showed that 13-E regulated the AMPK signaling pathway and influenced fatty acid metabolic processes, which may be attributed to its cardioprotective activities.

Exploring Aβ Proteotoxicity and Therapeutic Candidates Using Drosophila melanogaster

Alzheimer’s disease is a widespread and devastating neurological disorder associated with proteotoxic events caused by the misfolding and aggregation of the amyloid-β peptide. To find therapeutic strategies to combat this disease, Drosophila melanogaster has proved to be an excellent model organism that is able to uncover anti-proteotoxic candidates due to its outstanding genetic toolbox and resemblance to human disease genes. In this review, we highlight the use of Drosophila melanogaster to both study the proteotoxicity of the amyloid-β peptide and to screen for drug candidates. Expanding the knowledge of how the etiology of Alzheimer’s disease is related to proteotoxicity and how drugs can be used to block disease progression will hopefully shed further light on the field in the search for disease-modifying treatments.