Synergistic Augmentation of Beta-Lactams: Exploring Quinoline-Derived Amphipathic Small Molecules as Antimicrobial Potentiators against Methicillin-Resistant Staphylococcus aureus.

The escalation of bacterial resistance against existing therapeutic antimicrobials has reached a critical peak, leading to the rapid emergence of multidrug-resistant strains. Stringent pathways in novel drug discovery hinder our progress in this survival race. A promising approach to combat emerging antibiotic resistance involves enhancing conventional ineffective antimicrobials using low-toxicity small molecule adjuvants. Recent research interest lies in weak membrane-perturbing agents with unique cyclic hydrophobic components, addressing a significant gap in antimicrobial drug exploration. Our study demonstrates that quinoline-based amphipathic small molecules, SG-B-52 and SG-B-22, significantly reduce MICs of selected beta-lactam antibiotics (ampicillin and amoxicillin) against lethal methicillin-resistant Staphylococcus aureus (MRSA). Mechanistically, membrane perturbation, depolarization, and ROS generation drive cellular lysis and death. These molecules display minimal in vitro and in vivo toxicity, showcased through hemolysis assays, cell cytotoxicity analysis, and studies on albino Wistar rats. SG-B-52 exhibits impressive biofilm-clearing abilities against MRSA biofilms, proposing a strategy to enhance beta-lactam antibiosis and encouraging the development of potent antimicrobial potentiators.

Potential Broad-Spectrum Antimicrobial, Wound Healing, and Disinfectant Cationic Peptide Crafted from Snake Venom.

Antimicrobial cationic peptides are intriguing and propitious antibiotics for the future, even against multidrug-resistant superbugs. Venoms serve as a source of cutting-edge therapeutics and innovative, unexplored medicines. In this study, a novel cationic peptide library consisting of seven sequences was designed and synthesized from the snake venom cathelicidin, batroxicidin (BatxC), with the inclusion of the FLPII motif at the N-terminus. SP1V3_1 demonstrated exceptional antibacterial effectiveness against Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Klebsiella pneumoniae and destroyed the bacteria by depolarizing, rupturing, and permeabilizing their membranes, as evident from fluorescence assays, atomic force microscopy, and scanning electron microscopy. SP1V3_1 was observed to modulate the immune response in LPS-elicited U937 cells and exhibited good antibiofilm activity against MRSA and K. pneumoniae. The peptide promoted wound healing and disinfection in the murine model. The study demonstrated that SP1V3_1 is an exciting peptide lead and may be explored further for the development of better therapeutic peptides.

Amyloid-Inspired Engineered Multidomain Amphiphilic Injectable Peptide Hydrogel─An Excellent Antibacterial, Angiogenic, and Biocompatible Wound Healing Material.

The ingrained mechanical robustness of amyloids in association with their fine-tunable physicochemical properties results in the rational design and synthesis of tailor-made biomaterials for specific applications. However, the incredible antimicrobial efficacy of these ensembles has largely been overlooked. This research work provides an insight into the interplay between self-assembly and antimicrobial activity of amyloid-derived peptide amphiphiles and thereby establishes a newfangled design principle toward the development of potent antimicrobial materials with superior wound healing efficacy. Apart from the relationship with many neurodegenerative diseases, amyloids are now considered as an important cornerstone of our innate immune response against pathogenic microbes. Impelled by this observation, a class of amphiphilic antimicrobial peptide-based biomaterial has been designed by taking Aß42 as a template. The designed AMP due to its amphipathic nature undergoes rapid self-assembly to form a biocompatible supramolecular hydrogel network having significant antibacterial as well as wound healing effectivity on both Gram-negative P. aeruginosa and MRSA-infected diabetic wounds via reduced inflammatory response and enhanced angiogenesis. Results suggest that disease-forming amyloids can be used as a blueprint for the fabrication of biomaterial-based antimicrobial therapeutics by fine-tuning both the hydrophobicity of the ß-aggregation prone zone as well as membrane interacting cationic residues.

Controlling Amyloid Beta Peptide Aggregation and Toxicity by Protease-Stable Ligands.

Polymerization of soluble amyloid beta (Aß) peptide into protease-stable insoluble fibrillary aggregates is a critical step in the pathogenesis of Alzheimer's disease (AD). The N-terminal (NT) hydrophobic central domain fragment 16KLVFF20 plays an important role in the formation and stabilization of ß-sheets by self-recognition of the parent Aß peptide, followed by aggregation of Aß in the AD brain. Here, we analyze the effect of the NT region inducing ß-sheet formation in the Aß peptide by a single amino acid mutation in the native Aß peptide fragment. We designed 14 hydrophobic peptides (NT-01 to NT-14) by a single mutation at 18Val by using hydrophobic residues leucine and proline in the natural Aß peptide fragment (KLVFFAE) and analyzed its effect on the formation of Aß aggregates. Among all these peptides, NT-02, NT-03, and NT-13 significantly affected the Aß aggregate formation. When the NT peptides were coincubated with the Aß peptide, a significant reduction in ß-sheet formation and increment in random coil content of Aß was seen, confirmed by circular dichroism spectroscopy and Fourier transform infrared spectroscopy, followed by the reduction of fibril formation measured by the thioflavin-T (ThT) binding assay. The aggregation inhibition was monitored by Congo red and ThT staining and electron microscopic examination. Moreover, the NT peptides protect the PC-12 differentiated neurons from Aß-induced toxicity and apoptosis in vitro. Thus, manipulation of the Aß secondary structure with protease-stable ligands that promote the random coil conformation may provide a tool to control the Aß aggregates observed in AD patients.

Short Peptoid Evolved from the Key Hydrophobic Stretch of Amyloid-ß42 Peptide Serves as a Potent Therapeutic Lead of Alzheimer's Disease.

Amyloid-ß 42(Aß42), an enzymatically cleaved (1-42 amino acid long) toxic peptide remnant, has long been reported to play the key role in Alzheimer's disease (AD). Aß42 also plays the key role in the onset of other AD-related factors including hyperphosphorylation of tau protein that forms intracellular neurofibrillary tangles, imbalances in the function of the neurotransmitter acetylcholine, and even generation of reactive oxygen species (ROS), disrupting the cytoskeleton and homeostasis of the cell. To address these issues, researchers have tried to construct several strategies to target multiple aspects of the disease but failed to produce any clinically successful therapeutic molecules. In this article, we report a new peptoid called RA-1 that was designed and constructed from the hydrophobic stretch of the Aß42 peptide, 16KLVFFA21. This hydrophobic stretch is primarily responsible for the Aß42 peptide aggregation. Experimental study showed that the RA-1 peptoid is stable under proteolytic conditions, can stabilize the microtubule, and can inhibit the formation of toxic Aß42 aggregates by attenuating hydrophobic interactions between Aß42 monomers. Furthermore, results from various intracellular assays showed that RA-1 inhibits Aß42 fibril formation caused by the imbalance in AchE activity, reduces the production of cytotoxic reactive oxygen species (ROS), and promotes neurite outgrowth even in the toxic environment. Remarkably, we have also demonstrated that our peptoid has significant ability to improve the cognitive ability and memory impairment in in vivo rats exposed to AlCl3 and d-galactose (d-gal) dementia model. These findings are also validated with histological studies. Overall, our newly developed peptoid emerges as a multimodal potent therapeutic lead molecule against AD.

Evolution of Potential Antimitotic Stapled Peptides from Multiple Helical Peptide Stretches of the Tubulin Heterodimer Interface: Helix-Mimicking Stapled Peptide Tubulin Inhibitors.

Protein-protein interactions play a crucial role in microtubule dynamics. Microtubules are considered as a key target for the design and development of anticancer therapeutics, where inhibition of tubulin-tubulin interactions plays a crucial role. Here, we focused on a few key helical stretches at the interface of α,ß-tubulin heterodimers and developed a structural mimic of these helical peptides, which can serve as potent inhibitors of microtubule polymerization. To induce helicity, we have made stapled analogues of these sequences. Thereafter, we modified the lead sequences of the antimitotic stapled peptides with halo derivatives. It is observed that halo-substituted stapled peptides follow an interesting trend for the electronegativity of halogen atoms in interaction patterns with tubulin and a correlation in the toxicity profile. Remarkably, we found that para-fluorophenylalanine-modified stapled peptide is the most potent inhibitors, which perturbs microtubule dynamics, induces apoptotic death, and inhibits the growth of melanoma.

Design and Development of Benzothiazole-Based Fluorescent Probes for Selective Detection of Aß Aggregates in Alzheimer's Disease.

The formation and accumulation of amyloid beta (Aß) peptide are considered the crucial events that are responsible for the progression of Alzheimer's disease (AD). Herein, we have designed and synthesized a series of fluorescent probes by using electron acceptor-donor end groups interacting with a π-conjugating system for the detection of Aß aggregates. The chemical structure of these probes denoted as RMs, having a conjugated π-system (C═C), showed a maximum emission in PBS (>600 nm), which is the best range for a fluorescent imaging probe. Among all these probes, RM-28 showed an excellent fluorescence property with an emission maximum of >598 nm upon binding to Aß aggregates. RM-28 also showed high sensitivity (7.5-fold) and high affinities toward Aß aggregates (Kd = 175.69 ± 4.8 nM; Ka = 0.5 × 107 M-1). It can cross the blood-brain barrier of mice efficiently. The affinity of RM-28 toward Aß aggregates was observed in 3xTg-AD brain sections of the hippocampus and cortex region using a fluorescent imaging technique, as well as an in vitro fluorescence-based binding assay with Aß aggregates. Moreover, RM-28 is highly specific to Aß aggregates and does not bind with intracellular proteins like bovine serum albumin (BSA) and α-synuclein (α-Syn) aggregates. The results indicate that the probe RM-28 emerges as an efficient and veritable highly specific fluorescent probe for the detection of Aß aggregates in both in vitro and in vivo model systems.

A potent estrogen receptor and microtubule specific purine-benzothiazole-based fluorescent molecular probe induces apoptotic death of breast cancer cells.

Breast cancer is the most common malignancy in women and is a heterogeneous disease at molecular level. Early detection and specificity are the key prerequisite for the treatment of this deadly cancer. To address these issues attention on the breast cancer specific receptor protein(s) is the most realistic option. Herein estrogen (E) and progesterone (Pg) receptors(R) were considered to design fluorescent molecular probes with possible therapeutic option. We adopted QSAR technique to design a library of benzothiazole-purine hybrid molecules. Molecular docking offers us three screened molecules as most potential. Among these molecules one abbreviated as "CPIB" showed blue fluorescence and detected ER positive cancer cells at 1 nM concentration. At elevated concentration, CPIB induces apoptotic deaths of same cancer cells through targeting intracellular microtubules without affecting normal cells or ER negative cells. CPIB is one of its kind with two-in-one potential of "Detection and Destroy" ability targeting ER positive breast cancer cells.

Discovery of imidazole-based GSK-3ß inhibitors for transdifferentiation of human mesenchymal stem cells to neurons: A potential single-molecule neurotherapeutic foresight.

The transdifferentiation of human mesenchymal stem cells (hMSC) to functional neurons is crucial for the development of future neuro-regenerative therapeutics. Currently, transdifferentiation of hMSCs to neurons requires a "chemical cocktail" along with neural growth factors. The role of the individual molecules present in a "chemical cocktail" is poorly understood and may cause unwanted toxicity or adverse effects. Toward, this goal, we have showcased the discovery of an imidazole-based "single-molecule" transdifferentiation initiator SG-145C. This discovery was achieved via screening of a small molecule library through extensive in silico studies to shortlist the best-fitting molecules. This discovery evolved through a careful selection to target Glycogen synthase kinase-3ß (GSK-3ß), which is one of the important proteins responsible for neurogenesis. Rigorous computational experiments, as well as extensive biological assays, confirmed that SG-145C has significant potential to transdifferentiate hMSCs to neurons. Interestingly, our results suggest that SG-145C can inhibit the proteasomal degradation of phosphorylated ß-catenin, in turn promoting transdifferentiation of hMSCs into neurons via the Wnt pathway.

Fluorine Substituted Proline Enhances the Tubulin Binding Potential of a Tetrapeptide at the GTP Binding Pocket Causing the Inhibition of Microtubule Motility and an Antimitotic Effect.

The microtubule is regarded as the key target for designing anticancer and neurotherapeutic drugs due to its functional importance in eukaryotic cells including neurons. The microtubule is a dynamic hollow polymer tube consisting of α,ß-tubulin heterodimer. Polymerization of α,ß-tubulin heterodimer resulted in microtubule formation. GTP plays a crucial role in microtubule polymerization. It binds at the exchangeable binding site of the ß-tubulin heterodimer, and it is one of the most crucial therapeutic hot spots for designing anticancer therapeutics. In this manuscript, we have shown using an in silico strategy and various in vitro and cellular experiments that the binding affinity to the tubulin and cancer therapeutic potential of an exchangeable GTP/GDP binding antimitotic tetrapeptide (SP: Ser-Leu-Arg-Pro) is increased through changing proline with the multifluorine substituted proline. This study showcases the importance of the proline amino acid and its pyrrolidine ring in the regulation of binding with tubulin at the GTP binding pocket.

Human Serum Albumin-Inspired Glycopeptide-Based Multifunctional Inhibitor of Amyloid-ß Toxicity.

In Alzheimer's disease (AD), insoluble Aß42 peptide fragments self-aggregate and form oligomers and fibrils in the brain, causing neurotoxicity. Further, the presence of redox-active metal ions such as Cu2+ enhances the aggregation process through chelation with these Aß42 aggregates as well as generation of Aß42-mediated reactive oxygen species (ROS). Herein, we have adopted a bioinspired strategy to design and develop a multifunctional glycopeptide hybrid molecule (Glupep), which can serve as a potential AD therapeutic. This molecule consists of a natural metal-chelating tetrapeptide motif of human serum albumin (HSA), a ß-sheet breaker peptide, and a sugar moiety for better bioavailability. We performed different biophysical and docking experiments, which revealed that Glupep not only associates with Aß42 but also prevents its self-aggregation to form toxic oligomers and fibrils. Moreover, Glupep was also shown to sequester out Cu2+ from the Aß-Cu2+ complex, reducing the ROS formation and toxicity. Besides, this study also revealed that Glupep could protect PC12-derived neurons from Aß-Cu2+-mediated toxicity by reducing intracellular ROS generation and stabilizing the mitochondrial membrane potential. All these exciting features show Glupep to be a potent inhibitor of Aß42-mediated multifaceted toxicity and a prospective therapeutic lead for AD.

An overview of key potential therapeutic strategies for combat in the COVID-19 battle.

The sudden ravaging outbreak of a novel coronavirus, or SARS-CoV-2, in terms of virulence, severity, and casualties has already overtaken previous versions of coronaviruses, like SARS CoV and MERS CoV. Originating from its epicenter in Wuhan, China, this mutated version of the influenza virus with its associated pandemic effects has engulfed the whole world with awful speed. In the midst of this bewildering situation, medical and scientific communities are on their toes to produce the potential vaccine-mediated eradication of this virus. Though the chances are really high, to date no such panacea has been reported. The time requirements for the onerous procedures of human trials for the successful clinical translation of any vaccine or potential therapeutics are also a major concern. In order to build some resistance against this massive pandemic, the repurposing of some earlier antiviral drugs has been done, along with the refurbishment of some immune-responsive alternative avenues, like monoclonal antibody mediated neutralization, interferon treatment, and plasma therapy. New drugs developed from the RBD domain of the virus spike protein and drugs targeting viral proteases are also undergoing further research and have shown potential from preliminary results. The sole purpose of this review article is to provide a brief collective overview of the recent status of therapeutics advances and approaches, and their current state of implementation for the management of COVID-19.