A Potential Therapeutic Target Underling Binge Alcohol-Triggered Spontaneous Arrhythmia Onset in the Aged Heart

Background: Aging and binge alcohol abuse are both known as independent risk factors for both atrial and ventricular arrhythmias. With the COVID-19 pandemic, increased social isolation has significantly increased alcohol consumption worldwide. Older adults are a high-risk drinking group and alcohol significantly enhances the risk of arrhythmia onset. Yet, how alcohol (a secondary stressor) drives spontaneous atrial and ventricular arrhythmia onset in the aged heart (a primary stressor) remains unclear. Objective(s): We recently reported the stress-response kinase c-jun N-terminal kinase 2 (JNK2) underlies alcohol-enhanced atrial arrhythmia vulnerability (pacing-induced) in healthy young hearts. Here, we reveal a critical role of JNK2 in alcohol-driven arrhythmia onset in the aged heart in vivo. Method(s): Ambulatory ECGs were recorded using wireless telemeters in binge alcohol-exposed aged (24 months) and young mice (2 months). Spontaneous premature atrial and ventricular contractions (PACs, PVCs), atrial and ventricular tachycardia (AT, VT) were quantified as previously described. The role of JNK2 in triggered arrhythmic activities was assessed using a well-evaluated JNK2-specific inhibitor and our unique cardiac-specific MKK7D and MKK7D-JNK2dn mouse models with tamoxifen inducible overexpression of constitutively active MKK7 (a JNK upstream activator) or co-expression of MKK7D and inactive dominant negative JNK2 (JNK2dn). Result(s): We found that binge alcohol exposure in aged mice (n=14) led to spontaneous PACs/PVCs (75% of the mice), and AT/VT episodes (50%) along with a 21% mortality rate. However, alcohol-exposed young (n=5) and non-alcohol-exposed aged mice (n=11) were absent of any spontaneous arrhythmic activities or premature death. Intriguingly, JNK2-specific inhibition in vivo abolished those alcohol-associated triggered activities and mortality in aged mice. The causative role of JNK2 in triggered arrhythmias and premature death was further supported by the high frequency of spontaneous PACs/PVCs and nonsustained AT/VT episodes along with a 50% mortality rate in MKK7D mice (n=10), which was strikingly alleviated in MKK7D-JNK2dn mice (n=5) with cardiac-specific JNK2 competitive inhibition. Conclusion(s): Our findings are the first to reveal that stress kinase JNK2 underlies binge alcohol-evoked atrial and ventricular arrhythmia initiation in aged mice. Modulating JNK2 could be a novel therapeutic strategy to treat and/or prevent binge drinking-evoked cardiac arrhythmias.Copyright © 2023

Rational Design and Synthesis of D-galactosyl Lysophospholipids as Selective Substrates and non-ATP-competitive Inhibitors of Phosphatidylinositol Phosphate Kinases.

Phosphatidylinositol phosphate kinases (PIPKs) produce lipid signaling molecules and have been attracting increasing attention as drug targets for cancer, neurodegenerative diseases, and viral infection. Given the potential cross-inhibition of kinases and other ATP-utilizing enzymes by ATP-competitive inhibitors, targeting the unique lipid substrate binding site represents a superior strategy for PIPK inhibition. Here, by taking advantage of the nearly identical stereochemistry between myo-inositol and D-galactose, we designed and synthesized a panel of D-galactosyl lysophospholipids, one of which was found to be a selective substrate of phosphatidylinositol 4-phosphate 5-kinase. Derivatization of this compound led to the discovery of a human PIKfyve inhibitor with an apparent IC50 of 6.2 µM, which significantly potentiated the inhibitory effect of Apilimod, an ATP-competitive PIKfyve inhibitor under clinical trials against SARS-CoV-2 infection and amyotrophic lateral sclerosis. Our results provide the proof of concept that D-galactose-based phosphoinositide mimetics can be developed into artificial substrates and new inhibitors of PIPKs.

Inhibitory activity of copper gluconate and disulfiram against papain-like protease of SARS-CoV-2

Aim To investigate the inhibitory effect of copper gluconate and disulfiran on the PLpro of SARS-CoV-2 and to explore the effect of combination of them on PLpro.Methods SARS-CoV-2 PLpro was purified by recombinant expression technology of he effects of copper gluconate and disulfiram on PLpro activity were studied by enzyme kinetic method.Results Copper gluconate and disulfiram had high inhibitory activity on SARS-CoV-2 PLpro,Ubiquitin-7-Amino-4-methylcoumarin(Ub-AMC)was used as the fluorescent substrate.The IC50 of copper gluconate was 33.02 nmol.L-1,showing competitive inhibition,and the IC50 of disulfiram was 480.4 nmol.L-1,showing non competitive inhibition,and the combination of the two inhibitors showed the advantage of synergistic inhibition.Conclusions Copper gluconate and disulfiram have a high inhibitory effect on SARS-CoV-2 PLpro protein,and the combination shows the advantage of synergistic inhibition. Copyright © 2022 Publication Centre of Anhui Medical University. All rights reserved.

The SARS-CoV-2 Entry Inhibition Mechanisms of Serine Protease Inhibitors, OM-85, Heparin and Soluble HS Might Be Linked to HS Attachment Sites.

This article discusses the importance of D-xylose for fighting viruses (especially SARS-CoV-2) that use core proteins as receptors at the cell surface, by providing additional supporting facts that these viruses probably bind at HS/CS attachment sites (i.e., the hydroxyl groups of Ser/Thr residues of the core proteins intended to receive the D-xylose molecules to initiate the HS/CS chains). Essentially, the additional supporting facts, are: some anterior studies on the binding sites of exogenous heparin and soluble HS on the core proteins, the inhibition of the viral entry by pre-incubation of cells with heparin, and additionally, corroborating studies about the mechanism leading to type 2 diabetes during viral infection. We then discuss the mechanism by which serine protease inhibitors inhibit SARS-CoV-2 entry. The biosynthesis of heparan sulfate (HS), chondroitin sulfate (CS), dermatan sulfate (DS), and heparin (Hep) is initiated not only by D-xylose derived from uridine diphosphate (UDP)-xylose, but also bioactive D-xylose molecules, even in situations where cells were previously treated with GAG inhibitors. This property of D-xylose shown by previous anterior studies helped in the explanation of the mechanism leading to type 2 diabetes during SARS-CoV-2 infection. This explanation is completed here by a preliminary estimation of xyloside GAGs (HS/CS/DS/Hep) in the body, and with other previous studies helping to corroborate the mechanism by which the D-xylose exhibits its antiglycaemic properties and the mechanism leading to type 2 diabetes during SARS-CoV-2 infection. This paper also discusses the confirmatory studies of regarding the correlation between D-xylose and COVID-19 severity.

Efficacy of Silene arenosa extract on acetylcholinesterase in Bungarus sindanus (krait) venom.

OBJECTIVE: To examine the efficacy of Silene arenosa extract on acetylcholinesterase (AChE) of krait (Bungarus Sindanus) snake venom. METHODS: The present project designed to evaluate the inhibition of AChE by following standard procedures. RESULTS: Statistical analysis of the results showed that Silene arenosa exerted 73% inhibition against the krait venom acetylcholinesterase at fixed substrate acetylcholine (ACh) concentration (0.5 mM). Kinetic analysis using the Lineweaver Burk plot revealed that Silene arenosa caused a competitive type of inhibition i.e. Km values increased from 26.6 to 93.3 mM (26.6% to 93.3%) and Vmax remained constant in a concentration-dependent manner. Silene arenosa competes with the substrate to bind at the active site of the enzyme. The Kmapp of venom AChE for Silene arenosa increased from 60% to 81.6% and the Vmaxapp remains constant. Ki (inhibition constant was estimated to be 48 µg for snake venom; while the Km (Michaelis-Menten constant of AChE- substrate into AChE and product) was estimated to be 0.5 mM. The IC50 of AchE calculated for Silene arenosa was 67 µg. CONCLUSION: The present results suggest that Silene arenosa extract can be considered as an inhibitor of snake venom AChE.

In quest of small-molecules as potent non-competitive inhibitors against influenza.

A series of scaffolds namely aurones, 3-indolinones, 4-quinolones and cinnamic acid-piperazine hybrids, was designed, synthesized and investigated in vitro against influenza A/H1N1pdm09 virus. Designed molecules adopted different binding mode i.e., in 430-cavity of neuraminidase, unlike sialic acid and oseltamivir in molecular docking studies. All molecules reduced the viral titer and exhibited non-cytotoxicity along with cryo-protective property towards MDCK cells. Molecules (Z)-2-(3'-Chloro-benzylidene)-1,2-dihydro-indol-3-one (2f), (Z)-2-(4'-Chloro-benzylidene)-1,2-dihydro-indol-3-one (2g) and 2-(2'-Methoxy-phenyl)-1H-quinolin-4-one (3a) were the most interesting molecules identified in this research, endowed with robust potencies showing low-nanomolar EC50 values of 4.0 nM, 6.7 nM and 4.9 nM, respectively, compared to reference competitive and non-competitive inhibitors: oseltamivir (EC50 = 12.7 nM) and quercetin (EC50 = 0.56 µM), respectively. Besides, 2f, 2g and 3a exhibited good neuraminidase inhibitory activity in sub-micromolar range (IC50 = 0.52 µM, 3.5 µM, 1.3 µM respectively). Moreover, these molecules were determined as non-competitive inhibitors similar to reference non-competitive inhibitor quercetin unlike reference competitive inhibitor oseltamivir in kinetics studies.

Natural products as LSD1 inhibitors for cancer therapy.

Natural products generally fall into the biologically relevant chemical space and always possess novel biological activities, thus making them a rich source of lead compounds for new drug discovery. With the recent technological advances, natural product-based drug discovery is now reaching a new era. Natural products have also shown promise in epigenetic drug discovery, some of them have advanced into clinical trials or are presently being used in clinic. The histone lysine specific demethylase 1 (LSD1), an important class of histone demethylases, has fundamental roles in the development of various pathological conditions. Targeting LSD1 has been recognized as a promising therapeutic option for cancer treatment. Notably, some natural products with different chemotypes including protoberberine alkaloids, flavones, polyphenols, and cyclic peptides have shown effectiveness against LSD1. These natural products provide novel scaffolds for developing new LSD1 inhibitors. In this review, we mainly discuss the identification of natural LSD1 inhibitors, analysis of the co-crystal structures of LSD1/natural product complex, antitumor activity and their modes of action. We also briefly discuss the challenges faced in this field. We believe this review will provide a landscape of natural LSD1 inhibitors.

Decoy ACE2-expressing extracellular vesicles that competitively bind SARS-CoV-2 as a possible COVID-19 therapy.

The novel strain of coronavirus that appeared in 2019, SARS-CoV-2, is the causative agent of severe respiratory disease, COVID-19, and the ongoing pandemic. As for SARS-CoV that caused the SARS 2003 epidemic, the receptor on host cells that promotes uptake, through attachment of the spike (S) protein of the virus, is angiotensin-converting enzyme 2 (ACE2). In a recent article published by Batlle et al. (Clin. Sci. (Lond.) (2020) 134, 543-545) it was suggested that soluble recombinant ACE2 could be used as a novel biological therapeutic to intercept the virus, limiting the progression of infection and reducing lung injury. Another way, discussed here, to capture SARS-CoV-2, as an adjunct or alternative, would be to use ACE2+-small extracellular vesicles (sEVs). A competitive inhibition therapy could therefore be developed, using sEVs from engineered mesenchymal stromal/stem cells (MSCs), overexpressing ACE2.