Non-peptide fibrinogen receptor antagonists. 1. Discovery and design of exosite inhibitors

The In vitro evaluation of in silico-designed synthetic peptides AKVUAM-1 and AKVUAM-2 on human lung fibroblast cell line MRC5 and Mycobacterium tuberculosis isolates

Tuberculosis is a major global health problem caused by Mycobacterium tuberculosis and the increase in drug resistance is driving the need for new treatments. Today, various approaches are being applied in the development of drugs for the treatment of tuberculosis. Computer-aided drug design (CADD) enables the prediction of pharmacological efficacy for potential drug molecules during the design process. Thus, new therapeutic compounds can be developed that are more potent, less toxic and have fewer side effects than existing drugs. In this study, we investigated the in vitro activities of AKVUAM-1 and AKVUAM-2 synthetic peptides designed in silico by computer-aided drug design method to inhibit the interaction between M. tuberculosis outer membrane protein Cpn T and macrophage surface receptor CR-1 and Surfactant D protein. Notably, these synthetic peptides do not show cytotoxic effect on normal lung tissue and do not kill M. tuberculosis directly. The MIC values for AKVUAM-1 were higher than 512 μg/ml for all bacterial strains except IST-16 strain (128 μg/ml). According to our results, AKVUAM-1 and AKVUAM-2 synthetic peptides have the potential to be successful candidates for investigating their potential to block macrophage entry of bacilli as targeted.

Small molecule- and peptide-drug conjugates addressing integrins: A story of targeted cancer treatment

Targeted cancer treatment should avoid side effects and damage to healthy cells commonly encountered during traditional chemotherapy. By combining small molecule or peptidic ligands as homing devices with cytotoxic drugs connected by a cleavable or non-cleavable linker in peptide-drug conjugates (PDCs) or small molecule-drug conjugates (SMDCs), cancer cells and tumours can be selectively targeted. The development of highly affine, selective peptides and small molecules in recent years has allowed PDCs and SMDCs to increasingly compete with antibody-drug conjugates (ADCs). Integrins represent an excellent target for conjugates because they are overexpressed by most cancer cells and because of the broad knowledge about native binding partners as well as the multitude of small-molecule and peptidic ligands that have been developed over the last 30 years. In particular, integrin αVβ3 has been addressed using a variety of different PDCs and SMDCs over the last two decades, following various strategies. This review summarises and describes integrin-addressing PDCs and SMDCs while highlighting points of great interest.

Snake venom toxins: Potential anticancer therapeutics

Snake venom contains a cocktail of compounds dominated by proteins and peptides, which make up the toxin. The toxin components of snake venom attack several targets in the human body including the neuromuscular system, kidney and blood coagulation system and cause pathologies. As such, the venom toxins can be managed and used for the treatment of these diseases. In this regard, Captopril used in the treatment of cardiovascular diseases was the first animal venom toxin-based drug approved by the US Food and Drug Administration and the European Medicines Agency. Cancers cause morbidity and mortality worldwide. Due to side effects associated with the current cancer treatments including chemotherapy, radiotherapy, immunotherapy, hormonal therapy and surgery, there is a need to improve the efficacy of current treatments and/or develop novel drugs from natural sources including animal toxin-based drugs. There is a long history of earlier and ongoing studies implicating snake venom toxins as potential anticancer therapies. Here, we review the role of crude snake venoms and toxins including phospholipase A2, L-amino acid oxidase, C-type lectin and disintegrin as potential anticancer agents tested in cancer cell lines and animal tumour models in comparison to normal cell lines. Some of the anti-tumour activities of snake venom toxins include induction of cytotoxicity, apoptosis, cell cycle arrest and inhibition of metastasis, angiogenesis and tumour growth. We thus propose the advancement of multidisciplinary approaches to more pre-clinical and clinical studies for enhanced bioavailability and targeted delivery of snake venom toxin-based anticancer drugs.

CD61 identifies a superior population of aged murine HSCs and is required to preserve quiescence and self-renewal

ABSTRACT

Aging leads to a decline in function of hematopoietic stem cells (HSCs) and increases susceptibility to hematological disease. We found CD61 to be highly expressed in aged murine HSCs. Here, we investigate the role of CD61 in identifying distinct subpopulations of aged HSCs and assess how expression of CD61 affects stem cell function. We show that HSCs with high expression of CD61 are functionality superior and retain self-renewal capacity in serial transplantations. In primary transplantations, aged CD61High HSCs function similarly to young HSCs. CD61High HSCs are more quiescent than their CD61Low counterparts. We also show that in aged bone marrow, CD61High and CD61Low HSCs are transcriptomically distinct populations. Collectively, our research identifies CD61 as a key player in maintaining stem cell quiescence, ensuring the preservation of their functional integrity and potential during aging. Moreover, CD61 emerges as a marker to prospectively isolate a superior, highly dormant population of young and aged HSCs, making it a valuable tool both in fundamental and clinical research.

A Review of Rattlesnake Venoms

Venom components are invaluable in biomedical research owing to their specificity and potency. Many of these components exist in two genera of rattlesnakes, Crotalus and Sistrurus, with high toxicity and proteolytic activity variation. This review focuses on venom components within rattlesnakes, and offers a comparison and itemized list of factors dictating venom composition, as well as presenting their known characteristics, activities, and significant applications in biosciences. There are 64 families and subfamilies of proteins present in Crotalus and Sistrurus venom. Snake venom serine proteases (SVSP), snake venom metalloproteases (SVMP), and phospholipases A2 (PLA2) are the standard components in Crotalus and Sistrurus venom. Through this review, we highlight gaps in the knowledge of rattlesnake venom; there needs to be more information on the venom composition of three Crotalus species and one Sistrurus subspecies. We discuss the activity and importance of both major and minor components in biomedical research and drug development.

Quantitative Structure-Activity Relationship in the Series of 5-Ethyluridine, N2-Guanine, and 6-Oxopurine Derivatives with Pronounced Anti-Herpetic Activity

A quantitative analysis of the relationship between the structure and inhibitory activity against the herpes simplex virus thymidine kinase (HSV-TK) was performed for the series of 5-ethyluridine, N2-guanine, and 6-oxopurines derivatives with pronounced anti-herpetic activity (IC50 = 0.09 ÷ 160,000 μmol/L) using the GUSAR 2019 software. On the basis of the MNA and QNA descriptors and whole-molecule descriptors using the self-consistent regression, 12 statistically significant consensus models for predicting numerical pIC50 values were constructed. These models demonstrated high predictive accuracy for the training and test sets. Molecular fragments of HSV-1 and HSV-2 TK inhibitors that enhance or diminish the anti-herpetic activity are considered. Virtual screening of the ChEMBL database using the developed QSAR models revealed 42 new effective HSV-1 and HSV-2 TK inhibitors. These compounds are promising for further research. The obtained data open up new opportunities for developing novel effective inhibitors of TK.

Integrated Molecular Modeling and Machine Learning for Drug Design

Modern therapeutic development often involves several stages that are interconnected, and multiple iterations are usually required to bring a new drug to the market. Computational approaches have increasingly become an indispensable part of helping reduce the time and cost of the research and development of new drugs. In this Perspective, we summarize our recent efforts on integrating molecular modeling and machine learning to develop computational tools for modulator design, including a pocket-guided rational design approach based on AlphaSpace to target protein-protein interactions, delta machine learning scoring functions for protein-ligand docking as well as virtual screening, and state-of-the-art deep learning models to predict calculated and experimental molecular properties based on molecular mechanics optimized geometries. Meanwhile, we discuss remaining challenges and promising directions for further development and use a retrospective example of FDA approved kinase inhibitor Erlotinib to demonstrate the use of these newly developed computational tools.

Growing Utilization of Radical Chemistry in the Synthesis of Pharmaceuticals

Our current unhealthy lifestyle and the exponential surge in the population getting affected by a variety of diseases have made pharmaceuticals or drugs an imperative part of life, making the development of innovative strategies for drug discovery or the introduction of refined, cost-effective and modern technologies for the synthesis of clinically used drugs, a need of the hour. Ever since their discovery, free radicals and radical cations or anions as reactive intermediates have captivated the chemists, resulting in an exceptional utilization of these moieties throughout the field of chemical synthesis, owing to their unprecedented and widespread reactivity. Sticking with the idea of not judging the book by its cover, despite the conventional thought process of radicals being unstable and difficult to control entities, scientists and academicians around the globe have done an appreciable amount of work utilizing both persistent as well as transient radicals for a variety of organic transformations, exemplifying them with the synthesis of significant biologically active pharmaceutical ingredients. This review truly accounts for the organic radical transformations including radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling with metal-complexes and radical cations coupling with nucleophiles, that offers fascinating and unconventional approaches towards the construction of intricate structural frameworks of marketed APIs with high atom- and step-economy; complementing the otherwise employed traditional methods. This tutorial review presents a comprehensive package of diverse methods utilized for radical generation, featuring their reactivity to form critical bonds in pharmaceutical total synthesis or in building key starting materials or intermediates of their synthetic journey, acknowledging their excellence, downsides and underlying mechanisms, which are otherwise poorly highlighted in the literature. Despite great achievements over the past few decades in this area, many challenges and obstacles are yet to be unraveled to shorten the distance between the academics and the industry, which are all discussed in summary and outlook.

Snake venom disintegrins update: insights about new findings

Snake venom disintegrins are low molecular weight, non-enzymatic proteins rich in cysteine, present in the venom of snakes from the families Viperidae, Crotalidae, Atractaspididae, Elapidae, and Colubridae. This family of proteins originated in venom through the proteolytic processing of metalloproteinases (SVMPs), which, in turn, evolved from a gene encoding an A Disintegrin And Metalloprotease (ADAM) molecule. Disintegrins have a recognition motif for integrins in their structure, allowing interaction with these transmembrane adhesion receptors and preventing their binding to proteins in the extracellular matrix and other cells. This interaction gives disintegrins their wide range of biological functions, including inhibition of platelet aggregation and antitumor activity. As a result, many studies have been conducted in an attempt to use these natural compounds as a basis for developing therapies for the treatment of various diseases. Furthermore, the FDA has approved Tirofiban and Eptifibatide as antiplatelet compounds, and they are synthesized from the structure of echistatin and barbourin, respectively. In this review, we discuss some of the main functional and structural characteristics of this class of proteins and their potential for therapeutic use.

A Metalloproteinase Cocktail from the Venom of Protobothrops flavoviridis Cleaves Amyloid Beta Peptides at the α-Cleavage Site

A disintegrin and metalloproteinase (ADAM) family proteins are a major class of membrane-anchored multidomain proteinases that are responsible for the shedding of cell surface protein ectodomains, including amyloid precursor protein (APP). Human ADAM 9, 10, and 17 proteolyze APPs and produce non-amyloid-genic p3 peptides, instead of neurotoxic amyloid-β peptides (Aβs; Aβ40 and Aβ42), which form fibrils and accumulate in the brain of patients with Alzheimer's disease (AD). The ADAM family is closely related to snake venom metalloproteinases (SVMPs), which are derived from ancestral ADAMs but act as soluble proteinases. To test the therapeutic potential of SVMPs, we purified SVMPs from Protobothrops flavoviridis venom using metal ion affinity and pooled into a cocktail. Thus, 9 out of 11 SVMPs in the P. flavoviridis genome were identified in the cocktail. SVMPs inhibited Aβ secretion when added to human cell culture medium without affecting APP proteolysis. SVMPs degraded synthetic Aβ40 and Aβ42 peptides at the same cleavage site (α-site of APP) as ADAM9, 10, and 17. SVMPs did not degrade Aβ fibrils but interfered with their formation, assessed using thioflavin-T. Thus, SVMPs have therapeutic potential for AD as an Aβ-degrading protease, and the finding adds to the discovery of bioactive peptides from venoms as novel therapeutics.

Synthesis and Biological Evaluation of Cyclobutane-Based β3 Integrin Antagonists: A Novel Approach to Targeting Integrins for Cancer Therapy

The Arg-Gly-Asp (RGD)-binding family of integrin receptors, and notably the β3 subfamily, are key to multiple physiological processes involved in tissue development, cancer proliferation, and metastatic dissemination. While there is compelling preclinical evidence that both αvβ3 and αIIbβ3 are important anticancer targets, most integrin antagonists developed to target the β3 integrins are highly selective for αvβ3 or αIIbβ3. We report the design, synthesis, and biological evaluation of a new structural class of ligand-mimetic β3 integrin antagonist. These new antagonists combine a high activity against αvβ3 with a moderate affinity for αIIbβ3, providing the first evidence for a new approach to integrin targeting in cancer.

6D-QSAR for predicting biological activity of human aldose reductase inhibitors using quasar receptor surface modeling

The application of QSAR analysis dates back a half-century ago and is currently continuously employed in any rational drug design. The multi-dimensional QSAR modeling can be a promising tool for researchers to develop reliable predictive QSAR models for designing novel compounds. In the present work, we studied inhibitors of human aldose reductase (AR) to generate multi-dimensional QSAR models using 3D- and 6D-QSAR methods. For this purpose, Pentacle and Quasar's programs were used to produce the QSAR models using corresponding dissociation constant (K_d) values. By inspecting the performance metrics of the generated models, we achieved similar results with comparable internal validation statistics. However, considering the externally validated values, 6D-QSAR models provide significantly better prediction of endpoint values. The obtained results suggest that the higher the dimension of the QSAR model, the higher the performance of the generated model. However, more studies are required to verify these outcomes.

Clinical pharmacology of antiplatelet drugs

INTRODUCTION

Platelets play a key role in arterial thrombosis and antiplatelet therapy is pivotal in the treatment of cardiovascular disease. Current antiplatelet drugs target different pathways of platelet activation and show specific pharmacodynamic and pharmacokinetic characteristics, implicating clinically relevant drug-drug interactions.

AREAS COVERED

This article reviews the role of platelets in hemostasis and cardiovascular thrombosis, and discusses the key pharmacodynamics, drug-drug interactions and reversal strategies of clinically used antiplatelet drugs.

EXPERT OPINION

Antiplatelet therapies target distinct pathways of platelet activation: thromboxane A₂ synthesis, adenosine diphosphate-mediated signaling, integrin α_IIbβ₃ (GPIIb/IIIa), thrombin-mediated platelet activation via the PAR1 receptor and phosphodiesterases. Key clinical drug-drug interactions of antiplatelet agents involve acetylsalicylic acid - ibuprofen, clopidogrel - omeprazole, and morphine - oral P2Y₁₂ inhibitors, all of which lead to an attenuated antiplatelet effect. Platelet function and genetic testing and the use of scores (ARC-HBR, PRECISE-DAPT, ESC ischemic risk definition) may contribute to a more tailored antiplatelet therapy. High on-treatment platelet reactivity presents a key problem in the acute management of ST-elevation myocardial infarction (STEMI). A treatment strategy involving early initiation of an intravenous antiplatelet agent may be able to bridge the gap of insufficient platelet inhibition in high ischemic risk patients with STEMI.

Plant Metabolites as SARS-CoV-2 Inhibitors Candidates: In Silico and In Vitro Studies

Since it acquired pandemic status, SARS-CoV-2 has been causing all kinds of damage all over the world. More than 6.3 million people have died, and many cases of sequelae are in survivors. Currently, the only products available to most of the world’s population to fight the pandemic are vaccines, which still need improvement since the number of new cases, admissions into intensive care units, and deaths are again reaching worrying rates, which makes it essential to compounds that can be used during infection, reducing the impacts of the disease. Plant metabolites are recognized sources of diverse biological activities and are the safest way to research anti-SARS-CoV-2 compounds. The present study computationally evaluated 55 plant compounds in five SARS-CoV-2 targets such Main Protease (Mpro or 3CL or MainPro), RNA-dependent RNA polymerase (RdRp), Papain-Like Protease (PLpro), NSP15 Endoribonuclease, Spike Protein (Protein S or Spro) and human Angiotensin-converting enzyme 2 (ACE-2) followed by in vitro evaluation of their potential for the inhibition of the interaction of the SARS-CoV-2 Spro with human ACE-2. The in silico results indicated that, in general, amentoflavone, 7-O-galloylquercetin, kaempferitrin, and gallagic acid were the compounds with the strongest electronic interaction parameters with the selected targets. Through the data obtained, we can demonstrate that although the indication of individual interaction of plant metabolites with both Spro and ACE-2, the metabolites evaluated were not able to inhibit the interaction between these two structures in the in vitro test. Despite this, these molecules still must be considered in the research of therapeutic agents for treatment of patients affected by COVID-19 since the activity on other targets and influence on the dynamics of viral infection during the interaction Spro x ACE-2 should be investigated.

RhIII-Catalyzed C-H N-Heteroarylation and Esterification Cascade of Carboxylic Acid with Organoboron Reagents and 1,2-Dichloroethane in One-Pot Synthesis

A Rh^III-catalyzed C(sp²)-H N-heteroarylation and esterification cascade of aryl carboxylic acids with N-heteroaromatic boronates and 1,2-dichloroethane in a one-pot synthesis has been disclosed. The strong coordinating ability of ortho- and meta-substituted pyridine boronates and pyrazoles as well as unsubstituted pyrimidine allows them to serve as the coupling partners. This protocol allows late-stage modification of the key precursor of roflumilast and compounds of pharmaceutical interest, which highlights the potential application of this synthetic method.

Protein-Ligand Docking in the Machine-Learning Era

Molecular docking plays a significant role in early-stage drug discovery, from structure-based virtual screening (VS) to hit-to-lead optimization, and its capability and predictive power is critically dependent on the protein-ligand scoring function. In this review, we give a broad overview of recent scoring function development, as well as the docking-based applications in drug discovery. We outline the strategies and resources available for structure-based VS and discuss the assessment and development of classical and machine learning protein-ligand scoring functions. In particular, we highlight the recent progress of machine learning scoring function ranging from descriptor-based models to deep learning approaches. We also discuss the general workflow and docking protocols of structure-based VS, such as structure preparation, binding site detection, docking strategies, and post-docking filter/re-scoring, as well as a case study on the large-scale docking-based VS test on the LIT-PCBA data set.

The chemistry of snake venom and its medicinal potential

The fascination and fear of snakes dates back to time immemorial, with the first scientific treatise on snakebite envenoming, the Brooklyn Medical Papyrus, dating from ancient Egypt. Owing to their lethality, snakes have often been associated with images of perfidy, treachery and death. However, snakes did not always have such negative connotations. The curative capacity of venom has been known since antiquity, also making the snake a symbol of pharmacy and medicine. Today, there is renewed interest in pursuing snake-venom-based therapies. This Review focuses on the chemistry of snake venom and the potential for venom to be exploited for medicinal purposes in the development of drugs. The mixture of toxins that constitute snake venom is examined, focusing on the molecular structure, chemical reactivity and target recognition of the most bioactive toxins, from which bioactive drugs might be developed. The design and working mechanisms of snake-venom-derived drugs are illustrated, and the strategies by which toxins are transformed into therapeutics are analysed. Finally, the challenges in realizing the immense curative potential of snake venom are discussed, and chemical strategies by which a plethora of new drugs could be derived from snake venom are proposed.

Two-Photon Small-Molecule Fluorogenic Probes for Visualizing Endogenous Nitroreductase Activities from Tumor Tissues of a Cancer Patient

Nitroreductase (NTR), a common enzymatic biomarker of hypoxia, is widely used to evaluate tumor microenvironments. To date, numerous optical probes have been reported for NTRs detection. Approaches capable of concisely guiding the probe design of NTRs suitable for deep-tissue imaging, however, are still lacking. As such, direct optical imaging of endogenous NTR activities from tumors derived from cancer patients is thus far not possible. Herein, aided by computational calculations, the authors have successfully developed a series of two-photon (TP) small-molecule fluorogenic probes capable of sensitively detecting general NTR activities from various biological samples; by optimizing the distance between the recognition moiety and the reactive site of NTRs from different sources, the authors have discovered and experimentally proven that X4 displays the best performance in both sensitivity and selectivity. Furthermore, X4 shows excellent TP excited fluorescence properties capable of directly monitoring/imaging endogenous NTR activities from live mammalian cells, growing zebrafish, and tumor-bearing mice. Finally, with an outstanding TP tissue-penetrating imaging property, X4 is used, for the first time, to successfully detect endogenous NTR activities from the liver lysates and cardia tissues of a cancer patient. The work may provide a universal strategy to design novel TP small-molecule enzymatic probes in future clinical applications.

Pharmacosimulation of delays and interruptions during administration of tirofiban: a systematic comparison between EU and US dosage regimens

Tirofiban is a glycoproteine (GP) IIb/IIIa receptor antagonist, which inhibits platelet-platelet aggregation and is a potential adjunctive antithrombotic treatment in patients with acute coronary syndromes (ACS) or high-risk percutaneous coronary interventions (PCI). It is administered intravenously as a bolus followed by continuous infusion. However, the dosage recommendations in the United States (US) and European Union (EU) differ considerably. Furthermore, in routine clinical practice, deviations from the recommendations may occur. The objective of the present study was to investigate the impact of different alterations on tirofiban plasma concentrations in US and EU administration regimens and to give suggestions for delay management in clinical practice. We therefore mathematically simulated the effects of different bolus-infusion delays and infusion interruptions in different scenarios according to the renal function. Here, we provide a systematic assessment of concentration patterns of tirofiban in the US versus EU dosage regimens. We show that differences between the two regimens have important effects on plasma drug levels. Furthermore, we demonstrate that deviations from the proper administration mode affect the concentration of tirofiban. Additionally, we calculated the optimal dosage of a second bolus to rapidly restore the initial concentration without causing overdosage. In conclusion, differences in tirofiban dosing regimens between the U.S and EU and potential infusion interruptions have important effects on drug levels that may impact on degrees of platelet inhibition and thus antithrombotic effects. Thus, the findings of our modelling studies may help to explain differences in clinical outcomes observed in previous clinical trials on tirofiban.

Pd-catalysed C-H functionalisation of free carboxylic acids

Pd-catalysed C-H functionalisation of free carboxylic acids has drawn significant attention over the last few years due to the predominance of carboxylic acid moieties in pharmaceuticals and agrochemicals. But their coordinating ability was overlooked and masked by exogenous directing groups for a long time. Even other crucial roles of carboxylic acids as additives and steric inducers that directly influence the mode of a reaction have been widely neglected. This review aims to embrace all of the diverse aspects of carboxylic acids except additive and steric effects by concisely and systematically describing their versatile role in Pd-catalysed proximal and distal C-H activation reactions that could be implemented in the pharmaceutical and agrochemical industries. In addition, the mechanistic perspectives along with several recent strategies developed in the last few years discussed here will serve as educational resources for future research.

Strategies for Heterologous Expression, Synthesis, and Purification of Animal Venom Toxins

Animal venoms are complex mixtures containing peptides and proteins known as toxins, which are responsible for the deleterious effect of envenomations. Across the animal Kingdom, toxin diversity is enormous, and the ability to understand the biochemical mechanisms governing toxicity is not only relevant for the development of better envenomation therapies, but also for exploiting toxin bioactivities for therapeutic or biotechnological purposes. Most of toxinology research has relied on obtaining the toxins from crude venoms; however, some toxins are difficult to obtain because the venomous animal is endangered, does not thrive in captivity, produces only a small amount of venom, is difficult to milk, or only produces low amounts of the toxin of interest. Heterologous expression of toxins enables the production of sufficient amounts to unlock the biotechnological potential of these bioactive proteins. Moreover, heterologous expression ensures homogeneity, avoids cross-contamination with other venom components, and circumvents the use of crude venom. Heterologous expression is also not only restricted to natural toxins, but allows for the design of toxins with special properties or can take advantage of the increasing amount of transcriptomics and genomics data, enabling the expression of dormant toxin genes. The main challenge when producing toxins is obtaining properly folded proteins with a correct disulfide pattern that ensures the activity of the toxin of interest. This review presents the strategies that can be used to express toxins in bacteria, yeast, insect cells, or mammalian cells, as well as synthetic approaches that do not involve cells, such as cell-free biosynthesis and peptide synthesis. This is accompanied by an overview of the main advantages and drawbacks of these different systems for producing toxins, as well as a discussion of the biosafety considerations that need to be made when working with highly bioactive proteins.

Effect of GP IIb/IIIa inhibitor duration on the clinical prognosis of primary percutaneous coronary intervention in ST-segment elevation myocardial infarction with no-/slow-reflow phenomenon

BACKGROUND

In patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI) accompanied by the no-/slow-reflow phenomenon, the maintenance duration of GP IIb/IIIa inhibitor (GPI) is controversial. We compare the efficacy and safety of short- and long-term GPI infusion in STEMI patients with the no-/slow-reflow phenomenon.

METHODS

From June 2016 to December 2019, we continuously included patients with on-set STEMI who underwent pPCI, accompanied by the no-/slow-reflow, during interventional procedures at Guangdong Provincial People's Hospital and Zhuhai Golden Bay Hospital. The hemorrhage events, heart function, and major adverse cardiovascular events (MACE) were compared between < 24 h and ≥ 24 h GPI duration groups. The Kaplan-Meier curve was used to estimate the 1-year MACE-free survival at different GPI utility times.

RESULTS

In total, 127 patients were divided into two groups based on the duration of tirofiban use (less and more than 24 h). There was no significant difference between two groups in terms of baseline characteristics, plaque condition, and coronary physiological function. The two groups showed similar in-hospital MACE (1 [1.85%] vs. 4 [5.48%], p = 0.394) and 1-year MACE-free survival (log-rank test p = 0.9085). The 1-year MACE remained consistent between the two groups in all subgroups of different risk factors of no-/slow-reflow. There was no significant difference in heart function and in-hospital hemorrhage events (3.7% vs. 1.37%, p = 0.179).

CONCLUSION

In the real world, prolonging the duration of GPI may not significantly improve the clinical outcome in patients with STEMI with no-/slow-reflow.

Targeting protein-protein interactions in the DNA damage response pathways for cancer chemotherapy

Cellular DNA damage response (DDR) is an extensive signaling network that orchestrates DNA damage recognition, repair and avoidance, cell cycle progression and cell death. DDR alteration is a hallmark of cancer, with the deficiency in one DDR capability often compensated by a dependency on alternative pathways endowing cancer cells with survival and growth advantage. Targeting these DDR pathways has provided multiple opportunities for the development of cancer therapies. Traditional drug discovery has mainly focused on catalytic inhibitors that block enzyme active sites, which limits the number of potential drug targets within the DDR pathways. This review article describes the emerging approach to the development of cancer therapeutics targeting essential protein-protein interactions (PPIs) in the DDR network. The overall strategy for the structure-based design of small molecule PPI inhibitors is discussed, followed by an overview of the major DNA damage sensing, DNA repair, and DNA damage tolerance pathways with a specific focus on PPI targets for anti-cancer drug design. The existing small molecule inhibitors of DDR PPIs are summarized that selectively kill cancer cells and/or sensitize cancers to front-line genotoxic therapies, and a range of new PPI targets are proposed that may lead to the development of novel chemotherapeutics.

Advances in venom peptide drug discovery: where are we at and where are we heading?

Introduction: Animal venoms are a complex mixture of bioactive molecules that have evolved over millions of years for prey capture and defense from predators. Venom consists of many different types of molecules, with disulfide-rich peptides being a major component in most venoms. The study of these potent and highly selective molecules has led to the development of venom-derived drugs for diseases such as type 2 diabetes mellitus and chronic pain. As technologies have improved, more bioactive peptides have been discovered from venomous animals. Many of these molecules may have applications as tools for understanding normal and disease physiology, therapeutics, cosmetics or in agriculture.Areas covered: This article reviews venom-derived drugs approved by the FDA and venom-derived peptides currently in development. It discusses the challenges faced by venom-derived peptide drugs during drug development and the future for venom-derived peptides.Expert opinion: New techniques such as toxin driven discovery are expanding the pipeline of venom-derived peptides. There are many venom-derived peptides currently in preclinical and clinical trials that would have remained undiscovered using traditional approaches. A renewed focus on venoms, with advances in technology, will broaden the diversity of venom-derived peptide therapeutics and expand our knowledge of their molecular targets.

Peptidomimetics Therapeutics for Retinal Disease

Ocular disorders originating in the retina can result in a partial or total loss of vision, making drug delivery to the retina of vital importance. However, effectively delivering drugs to the retina remains a challenge for ophthalmologists due to various anatomical and physicochemical barriers in the eye. This review introduces diverse administration routes and the accordant pharmacokinetic profiles of ocular drugs to aid in the development of safe and efficient drug delivery systems to the retina with a focus on peptidomimetics as a growing class of retinal drugs, which have great therapeutic potential and a high degree of specificity. We also discuss the pharmacokinetic profiles of small molecule drugs due to their structural similarity to small peptidomimetics. Lastly, various formulation strategies are suggested to overcome pharmacokinetic hurdles such as solubility, retention time, enzymatic degradation, tissue targeting, and membrane permeability. This knowledge can be used to help design ocular delivery platforms for peptidomimetics, not only for the treatment of various retinal diseases, but also for the selection of potential peptidomimetic drug targets.

Discovery of a new class of integrin antibodies for fibrosis

Lung fibrosis, or the scarring of the lung, is a devastating disease with huge unmet medical need. There are limited treatment options and its prognosis is worse than most types of cancer. We previously discovered that MK-0429 is an equipotent pan-inhibitor of αv integrins that reduces proteinuria and kidney fibrosis in a preclinical model. In the present study, we further demonstrated that MK-0429 significantly inhibits fibrosis progression in a bleomycin-induced lung injury model. In search of newer integrin inhibitors for fibrosis, we characterized monoclonal antibodies discovered using Adimab's yeast display platform. We identified several potent neutralizing integrin antibodies with unique human and mouse cross-reactivity. Among these, Ab-31 blocked the binding of multiple αv integrins to their ligands with IC50s comparable to those of MK-0429. Furthermore, both MK-0429 and Ab-31 suppressed integrin-mediated cell adhesion and latent TGFβ activation. In IPF patient lung fibroblasts, TGFβ treatment induced profound αSMA expression in phenotypic imaging assays and Ab-31 demonstrated potent in vitro activity at inhibiting αSMA expression, suggesting that the integrin antibody is able to modulate TGFβ action though mechanisms beyond the inhibition of latent TGFβ activation. Together, our results highlight the potential to develop newer integrin therapeutics for the treatment of fibrotic lung diseases.

How not to discover a drug - integrins

INTRODUCTION

Integrins are a family of 24 cell adhesion receptors that play a role in the biggest unmet needs in medicine - cardiovascular disease, immunology and cancer. Their discovery promised huge potential for the pharmaceutical industry. Areas covered. Over 35-years since their discovery, there is little to show for the hundreds of billions of dollars of investment in anti-integrin drug discovery programmes. In this review the author discusses the reasons for the failure of this promising class of drugs and the future for this class of drugs. Expert opinion. Within 10-years, there was a plethora of potent, specific anti-integrin molecules and since their discovery, many of these agents have entered clinical trials. The success in discovering these agents was due to recently discovered monoclonal antibody technology. The integrin-recognition domain Arg-Gly-Asp (RGD) provided the basis for discovering small molecule inhibitors to integrins - both cyclic peptides and peptidomimetics. Most agents failed in the Phase III clinical trials and those agents that did make it to the market were plagued with issues of toxicity and limited efficacy and were soon replaced with non-integrin targeting agents. Their failure was due to a combination of poor pharmacokinetics and pharmacodynamics, complicated by the complex pathophysiology of integrins.

From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery

Animal poisons and venoms are comprised of different classes of molecules displaying wide-ranging pharmacological activities. This review aims to provide an in-depth view of toxin-based compounds from terrestrial and marine organisms used as diagnostic tools, experimental molecules to validate postulated therapeutic targets, drug libraries, prototypes for the design of drugs, cosmeceuticals, and therapeutic agents. However, making these molecules applicable requires extensive preclinical trials, with some applications also demanding clinical trials, in order to validate their molecular target, mechanism of action, effective dose, potential adverse effects, as well as other fundamental parameters. Here we go through the pitfalls for a toxin-based potential therapeutic drug to become eligible for clinical trials and marketing. The manuscript also presents an overview of the current picture for several molecules from different animal venoms and poisons (such as those from amphibians, cone snails, hymenopterans, scorpions, sea anemones, snakes, spiders, tetraodontiformes, bats, and shrews) that have been used in clinical trials. Advances and perspectives on the therapeutic potential of molecules from other underexploited animals, such as caterpillars and ticks, are also reported. The challenges faced during the lengthy and costly preclinical and clinical studies and how to overcome these hindrances are also discussed for that drug candidates going to the bedside. It covers most of the drugs developed using toxins, the molecules that have failed and those that are currently in clinical trials. The article presents a detailed overview of toxins that have been used as therapeutic agents, including their discovery, formulation, dosage, indications, main adverse effects, and pregnancy and breastfeeding prescription warnings. Toxins in diagnosis, as well as cosmeceuticals and atypical therapies (bee venom and leech therapies) are also reported. The level of cumulative and detailed information provided in this review may help pharmacists, physicians, biotechnologists, pharmacologists, and scientists interested in toxinology, drug discovery, and development of toxin-based products.

A BRET-based assay reveals collagen-Hsp47 interaction dynamics in the endoplasmic reticulum and small-molecule inhibition of this interaction

Molecular chaperones perform pivotal roles in proteostasis by engaging in protein–protein interactions (PPIs). The collagen-specific molecular chaperone Hsp47 (heat shock protein 47) interacts with procollagen in the endoplasmic reticulum (ER) and plays crucial roles in collagen synthesis. PPIs between Hsp47 and collagen could offer a therapeutic target for fibrosis, which is characterized by abnormal collagen accumulation in the extracellular matrix of fibrotic organs. Herein, we established a bioluminescence resonance energy transfer (BRET) system for assessing Hsp47–collagen interaction dynamics within the ER. After optimization and validation of the method, we could demonstrate inhibition of the interaction between Hsp47 and collagen by a small molecule (Col003) in the ER. Using the BRET system, we also found that Hsp47 interacts not only with the Gly-Pro-Arg motif but also weakly with Gly-Pro-Hyp motifs of triple-helical collagen in cells. Moreover, we found that the serpin loop of Hsp47 (SerpinH1) contributes to its binding to collagen. We propose that the method developed here can provide valuable information on PPIs between Hsp47 and collagen and on the effects of PPI inhibitors important for the management of fibrotic disorders.

Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting

Integrins are a family of transmembrane glycoprotein signaling receptors that can transmit bioinformation bidirectionally across the plasma membrane. Integrin αIIbβ3 is expressed at a high level in platelets and their progenitors, where it plays a central role in platelet functions, hemostasis, and arterial thrombosis. Integrin αIIbβ3 also participates in cancer progression, such as tumor cell proliferation and metastasis. In resting platelets, integrin αIIbβ3 adopts an inactive conformation. Upon agonist stimulation, the transduction of inside-out signals leads integrin αIIbβ3 to switch from a low- to high-affinity state for fibrinogen and other ligands. Ligand binding causes integrin clustering and subsequently promotes outside-in signaling, which initiates and amplifies a range of cellular events to drive essential platelet functions such as spreading, aggregation, clot retraction, and thrombus consolidation. Regulation of the bidirectional signaling of integrin αIIbβ3 requires the involvement of numerous interacting proteins, which associate with the cytoplasmic tails of αIIbβ3 in particular. Integrin αIIbβ3 and its signaling pathways are considered promising targets for antithrombotic therapy. This review describes the bidirectional signal transduction of integrin αIIbβ3 in platelets, as well as the proteins responsible for its regulation and therapeutic agents that target integrin αIIbβ3 and its signaling pathways.

Computational Approaches as Rational Decision Support Systems for Discovering Next-Generation Antitubercular Agents: Mini-Review

Tuberculosis, malaria, dengue, chikungunya, leishmaniasis etc. are a large group of neglected tropical diseases that prevail in tropical and subtropical countries, affecting one billion people every year. Minimal funding and grants for research on these scientific problems challenge many researchers to find a different way to reduce the extensive time and cost involved in the drug discovery cycle of these problems. Computer-aided drug design techniques have already been proved successful in the discovery of new molecules rationally by reducing the time and cost involved in the development of drugs. In the current minireview, we are highlighting on the molecular modeling studies published during 2010-2018 for target specific antitubercular agents. This review includes the studies of Structure-Based (SB) and Ligand-Based (LB) modeling and those involving Machine Learning (ML) techniques against different antitubercular targets such as dihydrofolate reductase (DHFR), enoyl Acyl Carrier Protein (ACP) reductase (InhA), catalase-peroxidase (KatG), enzyme antigen 85C, protein tyrosine phosphatases (PtpA and PtpB), dUTPase, thioredoxin reductase (MtTrxR), etc. The information presented in this review will help the researchers to get acquainted with the recent progress in the modeling studies of antitubercular agents.

Friends or Foes? Emerging Impacts of Biological Toxins

Toxins are substances produced from biological sources (e.g., animal, plants, microorganisms) that have deleterious effects on a living organism. Despite the obvious health concerns of being exposed to toxins, they are having substantial positive impacts in a number of industrial sectors. Several toxin-derived products are approved for clinical, veterinary, or agrochemical uses. This review sets out the case for toxins as 'friends' that are providing the basis of novel medicines, insecticides, and even nucleic acid sequencing technologies. We also discuss emerging toxins ('foes') that are becoming increasingly prevalent in a range of contexts through climate change and the globalisation of food supply chains and that ultimately pose a risk to health.

Dengue drug discovery: Progress, challenges and outlook

In the context of the only available vaccine (DENGVAXIA) that was marketed in several countries, but poses higher risks to unexposed individuals, the development of antivirals for dengue virus (DENV), whilst challenging, would bring significant benefits to public health. Here recent progress in the field of DENV drug discovery made in academic laboratories and industry is reviewed. Characteristics of an ideal DENV antiviral molecule, given the specific immunopathology provoked by this acute viral infection, are described. New chemical classes identified from biochemical, biophysical and phenotypic screens that target viral (especially NS4B) and host proteins, offer promising opportunities for further development. In particular, new methodologies ("omics") can accelerate the discovery of much awaited flavivirus specific inhibitors. Challenges and opportunities in lead identification activities as well as the path to clinical development of dengue drugs are discussed. To galvanize DENV drug discovery, collaborative public-public partnerships and open-access resources will greatly benefit both the DENV research community and DENV patients.

Protein-protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics

Antibiotics are potent pharmacological weapons against bacterial infections; however, the growing antibiotic resistance of microorganisms is compromising the efficacy of the currently available pharmacotherapies. Even though antimicrobial resistance is not a new problem, antibiotic development has failed to match the growth of resistant pathogens and hence, it is highly critical to discover new anti-infective drugs with novel mechanisms of action which will help reducing the burden of multidrug-resistant microorganisms. Protein-protein interactions (PPIs) are involved in a myriad of vital cellular processes and have become an attractive target to treat diseases. Therefore, targeting PPI networks in bacteria may offer a new and unconventional point of intervention to develop novel anti-infective drugs which can combat the ever-increasing rate of multidrug-resistant bacteria. This review describes the progress achieved towards the discovery of molecules that disrupt PPI systems in bacteria for which inhibitors have been identified and whose targets could represent an alternative lead discovery strategy to obtain new anti-infective molecules.

Identification of Effective Dimeric Gramicidin-D Peptide as Antimicrobial Therapeutics over Drug Resistance: In-Silico Approach

Discovering and developing the antimicrobial peptides are recently focused on pharmaceutical firm, since they serve as complementary to antibiotics in prevailing over drug resistance by eliciting the disruption of microbial membrane. Still, there are lots of challenges to bring up the structurally stable and functionally efficient antimicrobial peptides. It is well known that gramicidin D is the prominent antimicrobial peptide that exists as g-AB, g-BC, and g-AC. This study analyzes the structural stability and the functional activity of hetero-dimeric double-stranded gramicidin-D peptides, thereby demonstrating its potent antimicrobial activity against antibiotic-resistant micro-organisms. To investigate the structural stability and functionality of gramicidin D, we performed static and dynamic analysis. Initially, we observed a maximum number of intermolecular interactions and membrane penetration in g-AB as compared to g-BC and g-AC. To substantiate further, the geometrical and thermodynamic parameters revealed the retention of maximum stability in g-AB than g-AC and g-BC. Thus, the conformational free energy and the binding free energy showed the variation among gramicidin-D peptides for the prediction of increased stability and functionality. In conclusion, g-AB peptide has definitely demonstrated adequate structural stability and functionality and this work will need to be considered in peptide-based drug discovery.

Inhibitors of protein-protein interactions (PPIs): an analysis of scaffold choices and buried surface area

Protein-protein interactions (PPI) were once considered 'undruggable', but clinical successes, driven by advanced methods in drug discovery, have challenged that notion. Here, we review the last three years of literature on PPI inhibitors to understand what is working and why. From the 66 recently reported PPI inhibitors, we found that the average molecular weight was significantly greater than 500Da, but that this trend was driven, in large part, by the contribution of peptide-based compounds. Despite differences in average molecular weight, we found that compounds based on small molecules or peptides were almost equally likely to be potent inhibitors (K_D<1μM). Finally, we found PPIs with buried surface area (BSA) less than 2000Ų were more likely to be inhibited by small molecules, while PPIs with larger BSA values were typically inhibited by peptides. PPIs with BSA values over 4000Ų seemed to create a particular challenge, especially for orthosteric small molecules. Thus, it seems important to choose the inhibitor scaffold based on the properties of the target interaction. Moreover, this survey suggests a (more nuanced) conclusion to the question of whether PPIs are good drug targets; namely, that some PPIs are readily 'druggable' given the right choice of scaffold, while others still seem to deserve the 'undruggable' moniker.

Therapeutic Radiopharmaceuticals Targeting Integrin αvβ6

The epithelial integrin αvβ6 is expressed by many malignant carcinoma cell types, including pancreatic cancer, and thus represents a promising target for radionuclide therapy. The peptide cyclo(FRGDLAFp(NMe)K) was decorated with different chelators (DOTPI, DOTAGA, and DOTA). The Lu(III) complexes of these conjugates exhibited comparable αvβ6 integrin affinities (IC₅₀ ranging from 0.3 to 0.8 nM) and good selectivities against other integrins (IC₅₀ for αvβ8 >43 nM; for α5β1 >238 nM; and for αvβ3, αvβ5, and αIIbβ3 >1000 nM). Although different formal charges of the Lu(III) chelates (ranging from 0 to 4) resulted in strongly varying degrees of hydrophilicity (log D ranging from -3.0 to -4.1), biodistributions in murine H2009 xenografts of the Lu-177-labeled compounds (except the DOTPI derivative) were quite similar and comparable to our previously reported αvβ6 integrin positron emission tomography tracer Ga-68-avebehexin. Hence, combinations of existing Ga-68- and Lu-177-labeled c(FRGDLAFp(NMe)K) derivatives could be utilized for αvβ6 integrin-targeted theranostics, whereas our data nonetheless suggest that further improvement of pharmacokinetics might be necessary to ensure clinical success.

Intracoronary administration of tirofiban during percutaneous coronary intervention facilitates patients with acute coronary syndrome

We assessed the efficacy and safety of tirofiban intracoronary versus intravenous administration during percutaneous coronary intervention for patients with acute coronary syndrome. The databases of PubMed, Web of Science, China National Knowledge Infrastructure, and WanFang Database were retrieved. A total of 437 articles were found, according to inclusive and exclusive criteria, 13 of which were finally included. Compared with subjects with intravenous administration, those with intracoronary administration were more likely to reach thrombolysis in myocardial infarction trial grade 3 flow (relative risk = 1.17, 95% confidence interval: 1.11–1.22), improve left ventricular ejection fraction (Standardized mean difference = 0.65, 95% confidence interval: 0.20–1.11). Intracoronary administration resulted in a reduced risk of major adverse cardiovascular events at 30-day follow-up (relative risk = 0.47, 95% confidence interval: 0.34–0.65). However, incidence of bleeding complications was not statistically significant between two groups (relative risk = 0.76, 95% confidence interval: 0.55–1.04). Intracoronary administration of tirofiban can be more effective in increasing coronary blood flow and microvascular perfusion, more effective in improving postoperative myocardial reperfusion, more significantly in reducing the incidence of adverse cardiovascular events at 30-day’s follow-up and improving the prognosis after percutaneous coronary intervention without increasing the risk of bleeding.

Protein structure-based drug design: from docking to molecular dynamics

Recent years have witnessed rapid developments of computer-aided drug design methods, which have reached accuracy that allows their routine practical applications in drug discovery campaigns. Protein structure-based methods are useful for the prediction of binding modes of small molecules and their relative affinity. The high-throughput docking of up to 10⁶ small molecules followed by scoring based on implicit-solvent force field can robustly identify micromolar binders using a rigid protein target. Molecular dynamics with explicit solvent is a low-throughput technique for the characterization of flexible binding sites and accurate evaluation of binding pathways, kinetics, and thermodynamics. In this review we highlight recent advancements in applications of ligand docking tools and molecular dynamics simulations to ligand identification and optimization.

LMO1 Synergizes with MYCN to Promote Neuroblastoma Initiation and Metastasis

A genome-wide association study identified LMO1, which encodes an LIM-domain-only transcriptional cofactor, as a neuroblastoma susceptibility gene that functions as an oncogene in high-risk neuroblastoma. Here we show that dβh promoter-mediated expression of LMO1 in zebrafish synergizes with MYCN to increase the proliferation of hyperplastic sympathoadrenal precursor cells, leading to a reduced latency and increased penetrance of neuroblastomagenesis. The transgenic expression of LMO1 also promoted hematogenous dissemination and distant metastasis, which was linked to neuroblastoma cell invasion and migration, and elevated expression levels of genes affecting tumor cell-extracellular matrix interaction, including loxl3, itga2b, itga3, and itga5. Our results provide in vivo validation of LMO1 as an important oncogene that promotes neuroblastoma initiation, progression, and widespread metastatic dissemination.