Bifunctional Molecules That Induce Both Targeted Degradation and Transcytosis of Extracellular Proteins in Brain Cells.

Targeted protein degradation (TPD) has emerged as an effective therapeutic strategy for a wide range of diseases; however, the blood-brain barrier (BBB) limits access of degraders into the central nervous system (CNS). Here, we present a new class of bifunctional small molecules, called TransMoDEs (Transcytosis-inducing molecular degraders of extracellular proteins), capable of both (1) removal of target protein via lysosomal proteolysis and (2) transcytosis of protein targets across brain endothelial cells. TransMoDEs are derived from Angiopep-2, a peptide motif previously employed as a covalent tag to facilitate receptor-mediated transcytosis across the BBB. We demonstrate that TransMoDEs containing either a biotin or chloroalkane ligand can trigger endocytosis of streptavidin or HaloTag protein, respectively. Interestingly, although low-density lipoprotein receptor-related protein 1 (LRP1) has been reported as the primary receptor for Angiopep-2, TransMoDE-mediated target uptake does not rely exclusively on this pathway. Furthermore, TransMoDE-mediated endocytosis of streptavidin in a bEnd.3 BBB model occurs in a clathrin-mediated mechanism and results in both lysosomal localization and transcytosis of the target protein. This study demonstrates that TransMoDEs can recruit, transcytose, and degrade proteins of interest in cells relevant to the CNS, supporting their further development for the removal of pathogenic neuroproteins.

Potential of triazines in Alzheimer's disease: A versatile privileged scaffold.

Triazines are six-membered privileged scaffolds that have been explored in drug discovery programs owing to their stability in biological media and robust reactivity. Their unique chemical properties have led to the exploration of the triazine-containing molecules for multifaceted disorders like Alzheimer's disease (AD). The pathology of AD involves the interplay of multiple biochemical events such as amyloid beta-aggregation, formation of reactive oxygen species, cholinergic degradation, and metal ion dysregulation. The growing incidence of AD, coupled with the limited availability of efficacious medicines, necessitates the identification of newer therapeutic approaches. Privileged scaffolds like triazines with the potential for multiple biological effects offer excellent alternatives to the treatment of multifactorial AD. The present review describes numerous triazine-containing molecules capable of modulating single as well as multiple pathological factors involved in AD. The analysis of structural features of these molecules can provide useful insights for developing newer therapies.

Oxadiazole scaffolds in anti-tuberculosis drug discovery.

With the increasing number of cases of latent and drug resistant tuberculosis, there is an urgent need to develop new, potent molecules capable of combating this deadly disease. Molecules containing oxadiazoles are one such class that could be considered to fulfil this need. Oxadiazole regioisomers have been explored in drug discovery programs for their ability to act as effective linkers and also as pharmacophoric features. Oxadiazoles can act as bioisosteric replacements for the hydrazide moiety which can be found in first line anti-TB drugs, and some have been also reported to interact with newer anti-TB targets. In this context, the present review describes the potential of oxadiazoles as antituberculosis agents.

Antifolate Activity of Plant Polyphenols against Mycobacterium tuberculosis.

With the view of exploring phytochemicals as Mycobacterium tuberculosis (Mtb) dihydrofolate reductase inhibitors, known plant polyphenols from various classes were subjected to detailed docking studies. From this in-silico screening, seven polyphenols were selected and tested against Mtb H37 Rv in whole cell assays. The phytochemicals exhibited potential activity ranging from 3 to 183 µm. These molecules were then tested against the pathogenic and human enzymes in a high-throughput microtitre assay. Epigallocatechin gallate showed the best activity and selectivity. The in-silico analysis was in agreement with the assay results. Of these 7 polyphenols, 5 exhibiting minimum inhibitory concentration values of ≤15 µm were tested for synergistic activity with first line drug Ethambutol and second line folate inhibitor para-amino salicylic acid. Epigallocatechin gallate, Magnolol and Bakuchiol exhibited moderate synergistic association by lowering the minimum inhibitory concentration of these drugs. These simple phytochemicals could hence be considered as leads for further studies, or for preparation of semi-synthetic derivatives to be used in combination therapy, for increased anti-tuberculosis activity after validation in-vivo.

Targets, trials and tribulations in Alzheimer therapeutics.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by abnormal accumulation of extracellular amyloid beta senile plaques and intracellular neurofibrillary tangles in the parts of the brain responsible for cognition. The therapeutic burden for the management of AD relies solely on cholinesterase inhibitors that provide only symptomatic relief. The urgent need for disease-modifying drugs has resulted in intensive research in this domain, which has led to better understanding of the disease pathology and identification of a plethora of new pathological targets. Currently, there are over a hundred and seventy clinical trials exploring disease modification, cognitive enhancement, and reduction of neuro-psychiatric complications. However, the path to developing safe and efficacious AD therapeutics has not been without challenges. Several clinical trials have been terminated in advanced stages due to lack of therapeutic translation or increased incidence of adverse events. This review presents an in-depth look at the various therapeutic targets of AD and the lessons learnt during their clinical assessment. Comprehensive understanding of the implication of modulating various aspects of Alzheimer brain pathology is crucial for development of drugs with potential to halt disease progression in Alzheimer therapeutics.

Role of calcium dysregulation in Alzheimer's disease and its therapeutic implications.

The increasing incidence of Alzheimer's disease (AD) coupled with the lack of therapeutics to address the underlying pathology of the disease has necessitated the need for exploring newer targets. Calcium dysregulation represents a relatively newer target associated with AD. Ca+2 serves as an important cellular messenger in neurons. The concentration of the Ca+2 ion needs to be regulated at optimal concentrations intracellularly for normal functioning of the neurons. This is achieved with the help of mitochondria, endoplasmic reticulum, and neuronal plasma membrane channel proteins. Disruption in normal calcium homeostasis can induce formation of amyloid beta plaques, accumulation of neurofibrillary tangles, and dysfunction of synaptic plasticity, which in turn can affect calcium homeostasis further, thus forming a vicious cycle. Hence, understanding calcium dysregulation can prove to be a key to develop newer therapeutics. This review provides detailed account of physiology of calcium homeostasis and its dysregulation associated with AD. Further, with an understanding of various receptors and organelles involved in these pathways, the review also discusses various calcium channel blockers explored in AD hand in hand with some multitarget molecules addressing calcium as one of the targets.

Anti-Tuberculosis Mur Inhibitors: Structural Insights and the Way Ahead for Development of Novel Agents.

Mur enzymes serve as critical molecular devices for the synthesis of UDP-MurNAc-pentapeptide, the main building block of bacterial peptidoglycan polymer. These enzymes have been extensively studied for bacterial pathogens such as Escherichia coli and Staphylococcus aureus. Various selective and mixed Mur inhibitors have been designed and synthesized in the past few years. However, this class of enzymes remains relatively unexplored for Mycobacterium tuberculosis (Mtb), and thus offers a promising approach for drug design to overcome the challenges of battling this global pandemic. This review aims to explore the potential of Mur enzymes of Mtb by systematically scrutinizing the structural aspects of various reported bacterial inhibitors and implications concerning their activity. Diverse chemical scaffolds such as thiazolidinones, pyrazole, thiazole, etc., as well as natural compounds and repurposed compounds, have been reviewed to understand their in silico interactions with the receptor or their enzyme inhibition potential. The structural diversity and wide array of substituents indicate the scope of the research into developing varied analogs and providing valuable information for the purpose of modifying reported inhibitors of other multidrug-resistant microorganisms. Therefore, this provides an opportunity to expand the arsenal against Mtb and overcome multidrug-resistant tuberculosis.

Quantification of BERT Diagnosis Generalizability Across Medical Specialties Using Semantic Dataset Distance.

Deep learning models in healthcare may fail to generalize on data from unseen corpora. Additionally, no quantitative metric exists to tell how existing models will perform on new data. Previous studies demonstrated that NLP models of medical notes generalize variably between institutions, but ignored other levels of healthcare organization. We measured SciBERT diagnosis sentiment classifier generalizability between medical specialties using EHR sentences from MIMIC-III. Models trained on one specialty performed better on internal test sets than mixed or external test sets (mean AUCs 0.92, 0.87, and 0.83, respectively; p = 0.016). When models are trained on more specialties, they have better test performances (p < 1e-4). Model performance on new corpora is directly correlated to the similarity between train and test sentence content (p < 1e-4). Future studies should assess additional axes of generalization to ensure deep learning models fulfil their intended purpose across institutions, specialties, and practices.

Therapeutic potential of ferulic acid and its derivatives in Alzheimer's disease-A systematic review.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder primarily caused by accumulation of amyloid-beta (Aß) peptide extracellularly and neurofibrillary tangles intracellularly. Recently, it has been shown that oxidative stress and mitochondrial dysregulation play an important role in pathology of AD. Therefore, modulating various targets such as Aß aggregation, neuro-inflammation, and oxidative stress, genetic factors such as Apolipoprotein E gene (ApoE) are some of the ways to manage AD. Studying the natural products which can act as multifunctional agents could be key toward discovering new therapeutics. Ferulic acid (FA) represents one such natural product, which has exhibited great potential in this regard. Found in the plant cell walls, FA is an antioxidant, free radical scavenger with anti-inflammatory activity. Taking this into consideration, over the years, various derivatives have been reported as anti-AD molecules based on structure of FA. The present review explores the role of FA and its derivatives as therapeutic agents in AD.

Exploring the potential of pyrazoline containing molecules as Aß aggregation inhibitors in Alzheimer's disease.

Objectives Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disease in which one of the most prominent pathological features is accumulation of amyloid (Aß) plaques. This occurs due to the process of aggregation from monomeric to polymeric forms of Aß peptide and thus represents one of the attractive targets to treat AD. Methods After initial evaluation of a set of molecules containing N-acetylpyrazoline moiety flanked by aromatic rings on both sides as Aß aggregation inhibitors, the most potent molecules were further investigated for mechanistic insights. These were carried out by employing techniques such as circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), in vitro PAMPA-BBB (Blood-Brain Barrier) assay and cytotoxicity evaluation. Results Two molecules among the exploratory set displayed Aß aggregation inhibition comparable to standard curcumin. Among the follow-up molecules, several molecules displayed more inhibition than curcumin. These molecules displayed good inhibitory activity even at lower concentrations. CD and TEM confirmed the mechanism of Aß aggregation. These molecules were found to alleviate Aß induced cytotoxicity. BBB penetration studies highlighted the potential of these molecules to reach central nervous system (CNS). Conclusions Thus, several promising Aß-aggregation inhibitors were obtained as a result of this study.

In silico modeling of functionalized poly(methylvinyl ether/maleic acid) for controlled drug release in the ocular milieu.

Controlling structurally defined properties of drug-bound macromolecules such as surface adhesion and interaction with endogenous proteins in the surrounding environment using prior data from computer-assisted simulation can be of great use in designing controlled release macromolecular therapeutic systems. In this paper, we describe experimental correlation of real-time properties of a polymer with pendant drug molecules, with predicted values obtained from studying in silico molecular interactions of this polymer with ocular surface proteins (mucin) for formulating an ophthalmic in situ gel. Mucoretention of the drug (norfloxacin) within the eye sac is closely associated with binding interactions occurring on the ocular surface, and covalent association of the drug with the mucoadhesive polymer, poly(methylvinyl ether/maleic acid), can largely reduce dosing frequency eliciting prolonged antibacterial action much required in treating conjunctival infections. The physicochemical properties and 3D conformation of the drug-polymer conjugate were predicted by computational studies. Molecular docking of the drug-polymer conjugate with ocular surface mucin (MUC-1) suggested that amino acid residues Arg1095, Asn1091, and Gln1070 of mucin are involved in hydrogen bonding with carboxyl residues in the polymer structure. The orientation of the drug-polymer conjugate in solution profoundly depends on the properties of the drug. The studies further reveal that molecular interactions of MUC-1 with the drug in the drug-polymer conjugate influence the binding orientation of the drug-polymer to mucin. Computationally predicted solvation energies revealed a significant difference in energy values between drug molecule alone (- 113.04 kcal/mol) and the drug-polymer (- 492.44 kcal/mol) suggesting higher aqueous solvation of the drug-polymer conjugate compared with less-soluble drug, and that interactions between polymer chains and ocular aqueous environment dictate the drug-polymer conjugate's free energy. Our results demonstrate the fabrication of a macromolecular therapeutic gel using drug-polymer with controlled release properties and mucoadhesion guided by information predicted from computational software. Notably, in silico studies reveal that even small variations in molecular composition, in this case, an antibacterial drug that contributes less than half of the entire molecular weight can considerably change the drug's presentation to the ocular environment. Graphical abstract Table of contents graphic.

Network topology of LMWG cross-linked xyloglucan hydrogels for embedding hydrophobic nanodroplets: mechanistic insight and molecular dynamics.

Indigenous polymers have functional implications in biomedicine due to the presence of an inherent favorable structural architecture that supports hydrogel formation. In this study, we present the molecular level characterization of xyloglucan hydrogels using experimental and molecular simulation methods. We studied supramolecular self-assembly of tamarind seed-derived xyloglucan induced by low molecular weight gelators to form dense networks and rationalized its capabilities as a multifunctional and multiresponsive matrix for holding hydrophobic nanometric oleic acid globules intact for extended periods, preventing coalescence triggered instability using computational methods and imaging. Computational studies using molecular dynamics simulations provided mechanistic evidences of molecular associations supported by strong hydrogen bonding interactions responsible for fundamental gel network formation. Real-time imaging studies revealed that the gel matrix immobilizes intact oleic acid globules within its framework preventing coalescence. Molecular dynamics studies further showed key interactions of xyloglucan with the surfactant polysorbate 60 involved in sustaining oleic acid globules within the gel matrix, which corroborate with FE-SEM results. This study is an interesting approach to understand how molecular level associations in xyloglucan-based hydrogels can control and preserve nanosized hydrophobic oils imparting tenability and long-term droplet stability. The study also brings new insights into the conformational flexibility of xyloglucan around molecules with favorable and unfavorable interactive chemistries. Graphical abstract .

Exploration of 5-(5-nitrothiophen-2-yl)-4,5-dihydro-1H-pyrazoles as selective, multitargeted antimycobacterial agents.

We report the biological evaluation of 5-(5-nitrothiophen-2-yl)-4,5-dihydro-1H-pyrazole derivatives against bacteria, eukaryotic cell lines and the assessment of their mechanisms of action to determine their prospects of being developed into potent antituberculosis agents. The compounds were evaluated for their antibacterial property against Mycobacterium tuberculosis H37Rv, multidrug-resistant M. tuberculosis, Mycobacterium bovis BCG, Mycobacterium aurum, Escherichia coli, and Staphylococcus aureus using high-throughput spot-culture growth inhibition assay. They were found to be selective toward slow-growing mycobacteria and Gram-positive bacteria. In M. bovis BCG, they exhibited a bactericidal mode of action. Cytotoxicity was assessed in human THP-1 and murine RAW 264.7 cell lines, and the compounds showed a lower cytotoxicity potential when compared with their antibacterial activity. They were found to be excellent whole-cell efflux pump inhibitors of the mycobacterial surrogate M. aurum, performing better than known efflux pump inhibitor verapamil. The 5-nitrothiophene moiety was identified for the first time as a prospective inhibitor scaffold of mycobacterial arylamine N-acetyltransferase enzyme, which is the key enzyme in metabolizing isoniazid, a first-line antituberculosis drug. The two aforementioned findings make the compounds potential hits in the development of adjunctive tuberculosis therapy.

Design and synthesis of 5-(5-nitrothiophen-2-yl)-3-phenyl-4,5-dihydro-1H-pyrazole derivatives with improved solubility and potential antituberculosis activity.

We report the design-synthesis of several nitrothiophene containing molecules as antituberculosis agents. The molecules were designed on the basis of previously reported nitrofuran molecules in our laboratory, and the α,ß-unsaturated linker was modified to cyclized linker in order to overcome the challenge of low solubility and possible toxicity. The stereo-electronic properties such as HOMO, LUMO, and HOMO-LUMO gap along with other properties such as aqueous solvation energies and QPLogS values were studied. The designed molecules were synthesized and tested for in vitro antituberculosis activity, and some molecules were found to be highly active comparable to standard drugs. Further, the aqueous solubility was determined using visual inspection method and the designed molecules were found to be more soluble than their chalcone counterparts. Cytotoxicity studies were performed and the molecules were found to be non-cytotoxic. Electroanalytical studies proved nitro reduction as the mechanism of action for these molecules. Thus, this study provides potential nitrothiophene containing hits with improved solubility and reduced chances of toxicity.

Design and Synthesis of a Focused Library of Diamino Triazines as Potential Mycobacterium tuberculosis DHFR Inhibitors.

We report design of a series of 2,4-diamino triazines as Mycobacterium tuberculosis (Mtb) dihydrofolate reductase inhibitors. The synthesized compounds were evaluated against Mtb (H37Rv and Dormant stage H37Ra), their cytotoxicity was assessed (HepG2 and A549 cell lines), and selectivity toward Mtb was evaluated by testing against other bacterial strains. Some derivatives showed promising activity along with low cytotoxicity. The most potent compound in the whole cell assay (MIC 0.325 µM against H37Rv) showed selectivity in the enzyme assay and exhibited synergy with second line anti-TB agent p-amino salicylic acid. This study therefore provides promising molecules for further development as antituberculosis DHFR inhibitors.