An insight into prodrug strategy for the treatment of Alzheimer’s disease

Advancements in increasing efficiency of hydrogen sulfide in therapeutics: Strategies for targeted delivery as prodrugs

Hydrogen sulfide (H2S) has emerged as a potent therapeutic agent with diverse physiological functions, including vasodilation, anti-inflammation, and cytoprotection. However, its clinical application is limited due to its volatility and potential toxicity at high concentrations. To address these challenges, researchers have developed various H2S prodrugs that release H2S in a controlled and targeted manner. The review underscores the importance of targeting and delivery strategies in maximizing the therapeutic potential of H2S, a gasotransmitter with diverse physiological functions and therapeutic effects. By summarizing recent advancements, the review provides valuable insights for researchers and clinicians interested in harnessing the therapeutic benefits of H2S while minimizing off-target effects and toxicity. The integration of novel targeting and delivery approaches not only enhances the efficacy of H2S-based therapeutics but also expands the scope of potential applications, offering promising avenues for the development of new treatments for a variety of diseases and disorders.

A novel transgenic mouse line with hippocampus-dominant and inducible expression of truncated human tau

BACKGROUND

Intraneuronal accumulation of hyperphosphorylated tau is a defining hallmark of Alzheimer's disease (AD). However, mouse models imitating AD-exclusive neuronal tau pathologies are lacking.

METHODS

We generated a new tet-on transgenic mouse model expressing truncated human tau N1-368 (termed hTau368), a tau fragment increased in the brains of AD patients and aged mouse brains. Doxycycline (dox) was administered in drinking water to induce hTau368 expression. Immunostaining and Western blotting were performed to measure the tau level. RNA sequencing was performed to evaluate gene expression, and several behavioral tests were conducted to evaluate mouse cognitive functions, emotion and locomotion.

RESULTS

Dox treatment for 1-2 months at a young age induced overt and reversible human tau accumulation in the brains of hTau368 transgenic mice, predominantly in the hippocampus. Meanwhile, the transgenic mice exhibited AD-like high level of tau phosphorylation, glial activation, loss of mature neurons, impaired hippocampal neurogenesis, synaptic degeneration and cognitive deficits.

CONCLUSIONS

This study developed a well-characterized and easy-to-use tool for the investigations and drug development for AD and other tauopathies.

smProdrugs: A repository of small molecule prodrugs

In modern drug discovery and development, the prodrug approach has become a crucial strategy for enhancing the pharmacokinetic profiles of drugs. A prodrug is a chemical compound, which gets metabolized into a pharmacologically active form (drug) inside the body after its administration. In the current work, we report 'smProdrugs' (http://cheminfolab.in/databases/prodrug/), which is one of the first exclusive databases on small molecule prodrugs. It stores the structures, physicochemical properties and experimental ADMET data manually curated from literature. SmProdrugs lists 626 small molecule prodrugs and their active compounds with the above mentioned experimental data from 1808 research articles and 61 patents have been stored. The information page of each record gives the structures and properties of the prodrug and the active drug side by side which makes it easy for the user to instantly compare them. The structural modifications in the prodrug/active drugs are highlighted in a different colour for easy comparison. Experimental data has been curated from the downloaded PubMed and patent articles and were catalogued in a tabular form with more than 25 fields under sub-sections i) name and structures of the prodrugs and their active compounds, ii) mode of activation of the prodrug and enzyme/biocatalyst involved in the conversion, iii) indications/disease, iv) pharmacological target, v) experimental pharmacokinetic properties such as solubility, absorption, volume of distribution, half-life, clearance etc. and vi) information on the purpose/gain from the prodrug strategies. Considering the ever expanding utility of the prodrug approach smProdrugs will be of great use to the scientific community working on rational design of small molecule prodrugs.

Riluzole and its prodrugs for the treatment of Alzheimer's disease

Current medications for Alzheimer's disease help manage symptoms and behavioral problems. Nevertheless, they do not slow the progression of cognitive decline or dementia. A potential approach for treating Alzheimer's disease is to target neurons that are sensitive to disease pathobiology such as glutamatergic neurons. Several patents disclosed methods for treating Alzheimer's disease by administering riluzole or its prodrugs. Clinical trials revealed that 6 months treatment using riluzole or troriluzole is associated with a slower decline in the tomographic measures of the positron emissions of cerebral glucose metabolism in Alzheimer's patients. The proposed strategy claims to prevent and/or slow the cognitive decline of Alzheimer's patients and to enhance global functioning. These claims may also pave the way for other glutamate modulators to be used for Alzheimer's disease.

Olfactory Threshold Test as a Quick Screening Tool for Cognitive Impairment: Analysis of Two Independent Cohorts

BACKGROUND

Olfactory dysfunction appears prior to cognitive decline, and thus it has been suggested to be an early predictor of Alzheimer's disease. However, it is currently not known whether and how olfactory threshold test could serve as a quick screening tool for cognitive impairment.

OBJECTIVE

To define olfactory threshold test for screening cognitive impairment in two independent cohorts.

METHODS

The participants are comprised of two cohorts in China, 1,139 inpatients with type 2 diabetes mellitus (T2DM, Discovery cohort) and 1,236 community-dwelling elderly (Validation cohort). Olfactory and cognitive functions were evaluated by Connecticut Chemosensory Clinical Research Center test and Mini-Mental State Examination (MMSE), respectively. Regression analyses and receiver operating characteristic (ROC) analyses were carried out to determine the relation and discriminative performance of the olfactory threshold score (OTS) regarding identification of cognition impairment.

RESULTS

Regression analysis showed that olfactory deficit (reducing OTS) was correlated with cognitive impairment (reducing MMSE score) in two cohorts. ROC analysis revealed that the OTS could distinguish cognitive impairment from cognitively normal individuals, with mean area under the curve values of 0.71 (0.67, 0.74) and 0.63 (0.60, 0.66), respectively, but it failed to discriminate dementia from mild cognitive impairment. The cut-off point of 3 showed the highest validity for the screening, with the diagnostic accuracy of 73.3% and 69.5%.

CONCLUSION

Reducing OTS is associated with cognitive impairment in T2DM patients and the community-dwelling elderly. Therefore, olfactory threshold test may be used as a readily accessible screening tool for cognitive impairment.