Indirubins inhibit glycogen synthase kinase-3 beta and CDK5/p25, two protein kinases involved in abnormal tau phosphorylation in Alzheimer's disease. A property common to most cyclin-dependent kinase inhibitors?

Innovative pathological network-based multitarget approaches for Alzheimer's disease treatment

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease and is a major health threat globally. Its prevalence is forecasted to exponentially increase during the next 30 years due to the global aging population. Currently, approved drugs are merely symptomatic, being ineffective in delaying or blocking the relentless disease advance. Intensive AD research describes this disease as a highly complex multifactorial disease. Disclosure of novel pathological pathways and their interconnections has had a major impact on medicinal chemistry drug development for AD over the last two decades. The complex network of pathological events involved in the onset of the disease has prompted the development of multitarget drugs. These chemical entities combine pharmacological activities toward two or more drug targets of interest. These multitarget-directed ligands are proposed to modify different nodes in the pathological network aiming to delay or even stop disease progression. Here, we review the multitarget drug development strategy for AD during the last decade.

Identification of novel brain penetrant GSK-3β inhibitors toward Alzheimer's disease therapy by virtual screening, molecular docking, dynamic simulation, and MMPBSA analysis

One of the significant therapeutic targets for Alzheimer's disease (AD) is Glycogen Synthase Kinase-3β (GSK-3β). Inhibition of GSK-3β can prevent hyperphosphorylation of tau, and thus prevent formation and accumulation of neurofibrillary tangles and neuropil threads that block intracellular transport, trigger unfolded protein response, and increase oxidative stress, cumulatively leading to neurodegeneration. In this study, we have performed structure-based virtual screening of two small-molecule libraries from ChemDiv CNS databases using AutoDock Vina to identify hit molecules based on their binding affinities compared to that of an established GSK-3β inhibitor, indirubin-3'-monoxime (IMO). Pharmacoinformatic screening on SwissADME and pkCSM servers enabled identification of lead molecules with favorable pharmacoinformatic properties for drug likeliness, including blood brain barrier (BBB) permeability. Further, molecular dynamic simulations identified six candidate lead molecules that show stable complex formation with GSK-3β in dynamic state under physiological conditions. Principal component analysis of the dynamic state was used to plot Free Energy Landscapes (FELs) of GSK-3β-ligand complexes. STRIDE secondary structure analysis of the lowest energy conformations identified from FEL plots, and binding free energy calculations by Molecular Mechanics Poisson-Boltzmann Surface Area ((ΔGbind)MM-PBSA) of the simulation trajectories led to the identification of two ligands as potential lead molecules having favorable free energy landscape profiles as well as significantly lower (ΔGbind)MM-PBSA in dynamic state compared to that of reference inhibitor IMO. Hence, this study identifies two novel brain penetrant GSK-3β inhibitors that are likely to have therapeutic potential against Alzheimer's disease.

Benzimidazole-oxindole hybrids: A novel class of selective dual CDK2 and GSK-3β inhibitors of potent anticancer activity

A new series of benzimidazole-oxindole hybrids 8a-x was discovered as dual cyclin-dependent kinase (CDK2) and glycogen synthase kinase-3-beta (GSK-3β) inhibitors with potent anticancer activity. The synthesized hits displayed potent anticancer activity against national cancer institute cancer cell lines in single-dose and five-dose assays. Moreover, the derivatives 8k, 8l, 8n, 8o, and 8p demonstrated potent cytotoxic activity against PANC-1 cells with IC50 = 1.88-2.79 µM. In addition, the hybrids 8l, 8n, 8o, and 8p displayed potent antiproliferative activity on the MG-63 cell line (IC50 = 0.99-1.90 µM). Concurrently, the benzimidazole-oxindole hybrid 8v exhibited potent dual CDK2/GSK-3β inhibitory activity with IC50 values of 0.04 and 0.021 µM, respectively. In addition, 8v displayed more than 10-fold higher selectivity toward CDK2 and GSK-3 β over CDK1, CDK5, GSK-3α, vascular endothelial growth factor receptor-2, and B-rapidly accelerated fibrosarcoma. Screening of the effect of 8n and 8v on the cell cycle and apoptosis of PANC-1 and MG-63 cells displayed their ability to arrest their cell cycle at the G2-M phase and to potentiate the apoptosis of both cell lines. In silico docking of the benzimidazole-oxindole hybrid 8v into the catalytic pocket of both CDK2 and GSK-3β revealed its perfect fitting through the formation of hydrogen bonding and hydrophobic interactions with the key amino acids in the binding sites. In addition, in silico absorption, distribution, metabolism, excretion studies proved that 8a-x exhibit satisfactory drug-likeness properties for drug development.

Evolving significance of kinase inhibitors in the management of Alzheimer's disease

Alzheimer's disease is a neurodegenerative problem with progressive loss of memory and other cognitive function disorders resulting in the imbalance of neurotransmitter activity and signaling progression, which poses the need of the potential therapeutic target to improve the intracellular signaling cascade brought by kinases. Protein kinase plays a significant and multifaceted role in the treatment of Alzheimer's disease, by targeting pathological mechanisms like tau hyperphosphorylation, neuroinflammation, amyloid-beta production and synaptic dysfunction. In this review, we thoroughly explore the essential protein kinases involved in Alzheimer's disease, detailing their physiological roles, regulatory impacts, and the newest inhibitors and compounds that are progressing into clinical trials. All the findings of studies exhibited the promising role of kinase inhibitors in the management of Alzheimer's disease. However, it still poses the need of addressing current challenges and opportunities involved with this disorder for the future perspective of kinase inhibitors in the management of Alzheimer's disease. Further study includes the development of biomarkers, combination therapy, and next-generation kinase inhibitors with increased potency and selectivity for its future prospects.

Oxindole-benzothiazole hybrids as CDK2 inhibitors and anticancer agents: design, synthesis and biological evaluation

In the current study, molecular hybridization between the oxindole core and benzothiazole system through an acetohydrazide moiety was accomplished for the design of a new series of oxindole-benzothiazole hybrids 9a-r targeting CDK2 for cancer therapy. The afforded hybrids displayed promising growth inhibitory activity on NCI cancer cell lines at 10 µM. Compound 9o displayed mean GI% = 55.91%. Based on the potent activity of 9o, it was further assessed for its cytotoxic activity at five dose level and it demonstrated GI50 reaching 2.02 µM. Analysis of the cell cycle of the prostate cancer cell line DU145 after treatment with 9o confirmed its ability to arrest its cell cycle at the G1 phase. Moreover, 9o proved its ability to potentiate the apoptosis and necrosis of the same cell line. Furthermore, the oxindole-benzothiazole hybrids 9b, 9f and 9o showed IC50 = 0.70, 0.20 and 0.21 µM, respectively on CDK2. Besides, molecular docking simulation of the synthesized oxindole-benzothiazole hybrid 9o proved the expected binding mode which involves the accommodation of the oxindole moiety in the ATP binding pocket where it is involved in hydrogen bonding and hydrophobic interactions with the essential amino acids in the hinge region while the benzothiazole moiety is oriented toward the solvent region. Investigation of the physicochemical properties of the hybrids 9a-r highlights their acceptable ADME properties that can be somewhat developed for the discovery of new anticancer agents.

Discovery of novel and highly potential inhibitors of glycogen synthase kinase 3-beta (GSK-3β) through structure-based pharmacophore modeling, virtual computational screening, docking and in silico ADMET analysis

The protein Glycogen Synthase Kinase 3-Beta (GSK-3β), is a promising therapeutic target for treating various diseases such as neurodegenerative disorders, diabetes, inflammation and cancer. This study aims to investigate the potential of compounds targeting inflammation or carbohydrate metabolism to selectively inhibit GSK3β by binding to its ATP site. To achieve this goal, we filtered a database of 49367 molecules involved in carbohydrate metabolism or targeting inflammation using various computational analyses, including pharmacophore modeling, molecular docking, dynamic simulation, prime MM-GBSA calculation, and in silico ADME studies. We generated a pharmacophore model (hypo S: AADDHRR) using two different crystallographic complexes of GSK3β and evaluated the model's performance in identifying hits using various parameters, including EF, GH, ROC, AUC and BEDROC. Subsequently, we performed various dockings (HTVS, SP, XP and IFD) for the retrieved hits and found that, 5 out of the top 10 ranked compounds had the scaffold of pyrazolidine 3,5-dione, which has never been reported to inhibit kinases. We also conducted ADMET studies to and concluded that compound N6 exhibited the best pharmacokinetic profile passing the blood-brain barrier, possessing high lipophilicity and a high coefficient of skin permeability in the intestines, along with good bioavailability and low toxicity risk assessment. Dynamic simulation were also performed indicating that compounds N6 derived from pyrazolidine 3,5-dione demonstrated better binding potential for GSK3β during the simulation period. Therefore, we propose that compounds derived from pyrazolidine-3,5-dione, which modulate the activity of lysosomal alpha-glucosidase could serve as a novel scaffold for the selective inhibition of GSK-3β.Communicated by Ramaswamy H. Sarma.

Design, synthesis, antineoplastic activity of new pyrazolo[3,4-d]pyrimidine derivatives as dual CDK2/GSK3β kinase inhibitors; molecular docking study, and ADME prediction

In the current study, novel pyrazolo[3,4-d]pyrimidine derivatives 5a-h were designed and synthesized as targeted anti-cancer agents through dual CDK2/GSK-3β inhibition. The designed compounds demonstrated moderate to potent activity on the evaluated cancer cell lines (MCF-7 and T-47D). Compounds 5c and 5 g showed the most promising cytotoxic activity against the tested cell lines surpassing that of the used reference standard; staurosporine. On the other hand, both compounds showed good safety and tolerability on normal fibroblast cell line (MCR5). The final compounds 5c and 5 g showed a promising dual CDK2/GSK-3β inhibitory activity with IC50 of 0.244 and 0.128 μM, respectively, against CDK2, and IC50 of 0.317 and 0.160 μM, respectively, against GSK-3β. Investigating the effect of compounds 5c and 5 g on CDK2 and GSK-3β downstream cascades showed that they reduced the relative cellular content of phosphorylated RB1 and β-catenin compared to that in the untreated MCF-7 cells. Moreover, compounds 5c and 5 g showed a reasonable selective inhibition against the target kinases CDK2/GSK-3β in comparison to a set of seven off-target kinases. Furthermore, the most potent compound 5 g caused cell cycle arrest at the S phase in MCF-7 cells preventing the cells' progression to G2/M phase inducing cell apoptosis. Molecular docking studies showed that the final pyrazolo[3,4-d]pyrimidine derivatives have analogous binding modes in the target kinases interacting with the hinge region key amino acids. Molecular dynamics simulations confirmed the predicted binding mode by molecular docking. Moreover, in silico predictions indicated their favorable physicochemical and pharmacokinetic properties in addition to their promising cytotoxic activity.

A new 1,2,3-triazole-indirubin hybrid suppresses tumor growth and pulmonary metastasis by mitigating the HGF/c-MET axis in hepatocellular carcinoma

INTRODUCTION

Hepatocellular carcinoma (HCC) is a fatal cancer that is often diagnosed at the advanced stages which limits the available therapeutic options. The interaction of HGF with c-MET (a receptor tyrosine kinase) results in the activation of c-MET which subsequently triggers the PI3K/Akt/mTOR axis. Overexpression of c-MET in HCC tissues has been demonstrated to contribute to tumor progression and metastasis.

OBJECTIVES

We aimed to synthesize triazole-indirubin conjugates, examine their growth suppressor efficacy in cell-based assays, and investigate the antitumor as well as antimetastatic activity of lead cytotoxic agent in the orthotopic mice model.

METHODS

A series of triazole-indirubin hybrids were synthesized and cytotoxicity, apoptogenic, and antimigratory effect of the lead compound (CRI9) was evaluated using MTT assay, cell cycle analysis, annexin-V/PI assay, TUNEL assay, and wound healing assay. The effect of CRI9 on the operation of the HGF/c-MET/PI3K/Akt/mTOR axis was examined using western blotting and transfection experiments. Acute toxicity, antitumor, and antimetastatic activity of CRI9 were examined in NCr nude mice. The expression of c-MET/PI3K/Akt/mTOR, CD31, and Ki-67 was examined using immunohistochemistry and western blotting.

RESULTS

Among the new compounds, CRI9 consistently displayed potent cytotoxicity against HGF-induced HCC cells. CRI9 induced apoptosis as evidenced by increased sub G1 cells, annexin-V+/PI+ cells, TUNEL+ cells, and cleavage of procaspase-3 and PARP. CRI9 inhibited HGF-induced phosphorylation of c-METY1234/1235 and subsequently suppressed the PI3K/Akt/mTOR axis. Also, depletion of c-MET or inhibition of c-MET by CRI9 resulted in suppression of the PI3K/Akt/mTOR axis. CRI9 showed no toxic effects in NCr nude mice and displayed a potent antitumor and antimetastatic effect in the orthotopic HCC mice model. CRI9 also reduced the levels of phospho-c-MET, CD31, and Ki-67 and suppressed the activation of the PI3K/Akt/mTOR axis in tumor tissues.

CONCLUSION

CRI9 has been identified as a new inhibitor of the c-MET/PI3K/Akt/mTOR axis in HCC preclinical models.

Bromo-substituted indirubins for inhibition of protein kinase-mediated signalling involved in inflammatory mediator release in human monocytes

Targeting protein kinases that regulate signalling pathways in inflammation is an effective pharmacological approach to alleviate uncontrolled inflammatory diseases. In this context, the natural product indirubin and its 6-bromo-substituted analogue 6-bromoindirubin-3 -glycerol-oxime ether (6BIGOE; 1) were identified as potent inhibitors of glycogen synthase kinase-3β (GSK-3β). These inhibitors suppress the release of pro-inflammatory cytokines and prostaglandins (PG) from human monocytes. However, indirubin derivatives target several protein kinases such as cyclin-dependent kinases (CDKs) which has been a major concern for their application in inflammation therapy. Here, we report on a library of 13 5-bromo-substituted indirubin derivatives that have been designed to improve potency and target selectivity. Side-by-side comparison of reference compound 1 (6BIGOE) with 5-bromo derivatives revealed its isomer 2 (5BIGOE), as the most potent derivative able to supress pro-inflammatory cytokine and PG release in lipopolysaccharide-stimulated human monocytes. Analysis of protein kinase inhibition in intact monocytes, supported by our in silico findings, proposed higher selectivity of 1 for GSK-3β inhibition with lesser potency against CDKs 8 and 9. In contrast, 2 supressed the activity of these CDKs with higher effectiveness than GSK-3β, representing additional targets of indirubins within the inflammatory response. Encapsulation of 1 and 2 into polymer-based nanoparticles (NP) improved their pharmacological potential. In conclusion, the 5- and 6-brominated indirubins 1 and 2 as dual GSK-3β and CDK8/9 inhibitors represent a novel concept for intervention with inflammatory disorders.

Alkaloids as drug leads in Alzheimer's treatment: Mechanistic and therapeutic insights

Alzheimer's disease (AD) has few effective treatment options and continues to be a major global health concern. AD is a neurodegenerative disease that typically affects elderly people. Alkaloids have potential sources for novel drug discovery due to their diverse chemical structures and pharmacological activities. Alkaloids, natural products with heterocyclic nitrogen-containing structures, are considered potential treatments for AD. This review explores the neuroprotective properties of alkaloids in AD, focusing on their ability to regulate pathways such as amyloid-beta aggregation, oxidative stress, synaptic dysfunction, tau hyperphosphorylation, and neuroinflammation. The FDA has approved alkaloids such as acetylcholinesterase inhibitors like galantamine and rivastigmine. This article explores AD's origins, current market medications, and clinical applications of alkaloids in AD therapy. This review explores the development of alkaloid-based drugs for AD, focusing on pharmacokinetics, blood-brain barrier penetration, and potential adverse effects. Future research should focus on the clinical evaluation of promising alkaloids, developing recently discovered alkaloids, and the ongoing search for novel alkaloids for medical treatment. A pharmaceutical option containing an alkaloid may potentially slow down the progression of AD while enhancing its symptoms. This review highlights the potential of alkaloids as valuable drug leads in treating AD, providing a comprehensive understanding of their mechanisms of action and therapeutic implications.

Amelioration of cisplatin-induced neurodegenerative changes in rats and restoration of mitochondrial biogenesis by 6-bromoindirubin-3'-oxime: The implication of the GSK-3β/PGC1-α axis

BACKGROUND

The cognitive deficits observed after treatment with chemotherapeutic drugs are obvious clinical problems. For treating chemotherapy-induced cognitive deficits (CICD), the treatment modalities must target its underlying mechanisms. Specifically, cisplatin may activate glycogen synthase kinase-3β (GSK-3β), thereby enhancing neuronal apoptosis. 6-bromoindirubin-3'-oxime (6BIO) was not investigated previously in a model of CICD. Therefore, this investigation aimed to address the impacts of GSK3 inhibition on regulating cell signaling, which contributes to neurodegeneration and cognitive impairment.

METHODS

Thirty adult male Wistar rats were randomly allocated into control groups, while two experimental groups were exposed to repeated cisplatin injections (2 mg/kg intraperitoneally (ip), twice weekly, nine injections), termed chemobrain groups. The rats in the two experimental groups were equally divided into the chemobrain group (untreated) and the chemobrain-6BIO group (treated with 6BIO at a dose of 8.5 μg/kg ip every two days, started after the last dose of cisplatin and continued for two weeks).

RESULTS

Repeated exposure to cisplatin led to a marked decline in cognitive functions. GSK3 inhibition exerted neuroprotection by decreasing the expression of p-tau and amyloid β, thereby improving cognition. 6BIO, the GSK-3β inhibitor, restored mitochondrial biogenesis by augmenting the protein levels of PGC1-α and increasing the number of mitochondria in the cerebral cortex and hippocampus.

CONCLUSION

6BIO provided neuroprotection and exhibited anti-apoptotic and anti-oxidative effects in a rat model of chemobrain.

Discovery and optimization of narrow spectrum inhibitors of Tousled like kinase 2 (TLK2) using quantitative structure activity relationships

The oxindole scaffold has been the center of several kinase drug discovery programs, some of which have led to approved medicines. A series of two oxindole matched pairs from the literature were identified where TLK2 was potently inhibited as an off-target kinase. The oxindole has long been considered a promiscuous kinase inhibitor template, but across these four specific literature oxindoles TLK2 activity was consistent, while the kinome profile was radically different ranging from narrow to broad spectrum kinome coverage. We synthesized a large series of analogues, utilizing quantitative structure-activity relationship (QSAR) analysis, water mapping of the kinase ATP binding sites, kinome profiling, and small-molecule x-ray structural analysis to optimize TLK2 inhibition and kinome selectivity. This resulted in the identification of several narrow spectrum, sub-family selective, chemical tool compounds including 128 (UNC-CA2-103) that could enable elucidation of TLK2 biology.

Discovery of novel quinolin-2-one derivatives as potential GSK-3β inhibitors for treatment of Alzheimer's disease: Pharmacophore-based design, preliminary SAR, in vitro and in vivo biological evaluation

Recently, glycogen synthase kinase-3β (GSK-3β) has been considered as a critical factor implicated in Alzheimer's disease (AD). In a previous work, a 3D pharmacophore model for GSK-3β inhibitors was created and the results suggested that derivative ZINC67773573, VIII, may provide a promising lead for developing novel GSK-3β inhibitors for the AD's treatment. Consequently, in this work, novel series of quinolin-2-one derivatives were synthesized and assessed for their GSK-3β inhibitory properties. In vitro screening identified three compounds: 7c, 7e and 7f as promising GSK-3β inhibitors. Compounds 7c, 7e and 7f were found to exhibit superior inhibitory effect on GSK-3β with IC50 value ranges between 4.68 ± 0.59 to 8.27 ± 0.60 nM compared to that of staurosporine (IC50 = 6.12 ± 0.74 nM). Considerably, compounds 7c, 7e and 7f effectively lowered tau hyperphosphorylated aggregates and proving their safety towards the SH-SY5Y and THLE2 normal cell lines. The most promising compound 7c alleviated cognitive impairments in the scopolamine-induced model in mice. Compound 7c's activity profile, while not highly selective, may provide a starting point and valuable insights into the design of multi-target inhibitors. According to the ADME prediction results, compounds 7c, 7e and 7f followed Lipinski's rule of five and could almost permeate through the BBB. Molecular docking simulations showed that these compounds are well accommodated in the ATP binding site interacting by its quinoline-2-one ring through hydrogen bonding with the key amino acids Asp133 and Val135 at the hinge region. The findings of this study suggested that these new compounds may have potential as anti-AD drugs targeting GSK-3β.

Indirubin alleviates retinal neurodegeneration through the regulation of PI3K/AKT signaling

Retinal neurodegenerative disease is a leading cause of blindness among the elderly in developed countries, including glaucoma, diabetic retinopathy, traumatic optic neuropathy and optic neuritis, etc. The current clinical treatment is not very effective. We investigated indirubin, one of the main bioactive components of the traditional Chinese medicine Danggui Longhui Pill, in the present study for its role in retinal neurodegeneration. Indirubin exhibited no detectable tissue toxicity in vivo or cytotoxicity in vitro. Moreover, indirubin improved visual function and ameliorated retinal neurodegeneration in mice after optic nerve crush injury in vivo. Furthermore, indirubin reduced the apoptosis of retinal ganglion cells induced by oxidative stress in vitro. In addition, indirubin significantly suppressed the increased production of intracellular reactive oxygen species and the decreased activity of superoxide dismutase induced by oxidative stress. Mechanically, indirubin played a neuroprotective role by regulating the PI3K/AKT/BAD/BCL-2 signaling. In conclusion, indirubin protected retinal ganglion cells from oxidative damage and alleviated retinal neurodegeneration induced by optic nerve crush injury. The present study provides a potential therapeutic medicine for retinal neurodegenerative diseases.

Synthesis, biological activity evaluation and mechanism of action of novel bis-isatin derivatives as potential anti-liver cancer agents

A series of bis-isatin conjugates with lysine linker were synthesized with the aim of probing their antiproliferative potential. All the newly synthesized derivatives (0-100 μM) were first screened against liver cancer cell lines(Huh1, H22, Huh7, Hepa1-6, HepG2, Huh6 and 97H) using CCK-8 assay. Results indicated that the derivative 4d exhibited the most potent activity against Huh1 (IC50 = 17.13 µM) and Huh7(IC50 = 8.265 µM). In vivo anti-tumor study showed that compound 4d effectively inhibited tumor growth in Huh1-induced xenograft mouse model; the anti-tumor effect of compound 4d (15 mg/kg) was comparable with sorafenib (20 mg/kg). H&E staining analysis and routine blood test and blood serum biochemistry examination was performed to confirm the safety of compound 4d in xenograft models. The mechanism of action of 4d on tumor growth inhibition was further investigated by RNA-Seq analysis, which indicates a positive regulation of autophagy signaling pathway, which was further confirmed with key biomarker expression of autophagy after 4d treatment. Our results suggest that the bis-isatin conjugate compound 4d is a promising tumor inhibitory agent for some liver cancer.

Theoretical characterization and biological activity investigation of indirubins, cyclin dependent kinases inhibitors

Up to now, significant research efforts have been directed towards investigating indirubin and its derivatives as potential candidates for developing new compounds with multiple biological activities. In the present work, natural indirubin and numerous of its chemical derivatives referred to as indirubins have been investigated computationally using DFT method with the B3LYP/6-311 + G(d,p) level of theory, in order to reveal structure- biological activity relationship. We started with a structural properties description. Results analysis indicated that extra interaction sites were provided through the set of substitutions in compounds (1): Indirubin-3'-monoxime, (2): Indirubin-5-sulfonic acid, (3): 5-Nitro-indirubinoxime, (4): 5'-OH-5-nitro-indirubinoxime (AGM130), (5): 7-Bromo-5'-carboxyindirubin-3'-oxime, and (6): 7 BIO and consequently, extra hydrogen bonds may be formed with the active sites of molecular targets, such as GSK-3, CDKs, and Aurora kinases, as well as the aryl hydrocarbon receptor. Subsequently, to get more information on the electronic properties of indirubin and its analogues, HOMO, LUMO, Egap, and further electronic parameters were carried out. The indirubin derivatives showed an easier interaction with its environment than indirubin, the parent compound. The UV-Visible spectra of indirubin and compounds 1-6 were also produced using TD-DFT with B3LYP functional and 6-311 + G(2d,p) basis set. The relationship between absorption and chemical structure is discussed. Two phototoxic brominated compounds showed important absorption spectra modifications. It was also found that the main absorption bands of all compounds derived from π→π*(HOMO→LUMO) transitions.Communicated by Ramaswamy H. Sarma.

Discovery and optimization of indirubin derivatives as novel ferroptosis inducers for the treatment of colon cancer

Glutathione peroxidase 4 (GPX4) is an essential antioxidant enzyme that negatively regulates ferroptosis. To exploit novel GPX4 inhibitors, we designed and synthesized 32 indirubin derivatives. Compound 31 exhibited the strongest antitumor activity against HCT-116 cells (IC50 = 0.49 ± 0.02 μM). Further studies suggested that 31 could induce ferroptosis in colon cancer cells and its cytotoxic activity could be reversed by ferroptosis inhibitors. Mechanism research showed that 31 promoted the degradation of GPX4, causing the accumulation of lipid ROS to induce ferroptosis. Animal experiments also proved that 31 could inhibit the growth of colon cancer cells in vivo and reduce the expression of GPX4 in tumor tissues. These results indicated that compound 31 had potential as a novel ferroptosis inducer agent for colon cancer.

Protein Kinases and their Inhibitors Implications in Modulating Disease Progression

Protein phosphorylation plays an important role in cellular pathways, including cell cycle regulation, metabolism, differentiation and survival. The protein kinase superfamily network consists of 518 members involved in intrinsic or extrinsic interaction processes. Protein kinases are divided into two categories based on their ability to phosphorylate tyrosine, serine, and threonine residues. The complexity of the system implies its vulnerability. Any changes in the pathways of protein kinases may be implicated in pathological processes. Therefore, they are regarded as having an important role in human diseases and represent prospective therapeutic targets. This article provides a review of the protein kinase inhibitors approved by the FDA. Finally, we summarize the mechanism of action of protein kinases, including their role in the development and progression of protein kinase-related roles in various pathological conditions and the future therapeutic potential of protein kinase inhibitors, along with links to protein kinase databases. Further clinical studies aimed at examining the sequence of protein kinase inhibitor availability would better utilize current protein kinase inhibitors in diseases. Additionally, this review may help researchers and biochemists find new potent and selective protein kinase inhibitors and provide more indications for using existing drugs.

The Fundamental Role of Oxime and Oxime Ether Moieties in Improving the Physicochemical and Anticancer Properties of Structurally Diverse Scaffolds

The present review explores the critical role of oxime and oxime ether moieties in enhancing the physicochemical and anticancer properties of structurally diverse molecular frameworks. Specific examples are carefully selected to illustrate the distinct contributions of these functional groups to general strategies for molecular design, modulation of biological activities, computational modeling, and structure-activity relationship studies. An extensive literature search was conducted across three databases, including PubMed, Google Scholar, and Scifinder, enabling us to create one of the most comprehensive overviews of how oximes and oxime ethers impact antitumor activities within a wide range of structural frameworks. This search focused on various combinations of keywords or their synonyms, related to the anticancer activity of oximes and oxime ethers, structure-activity relationships, mechanism of action, as well as molecular dynamics and docking studies. Each article was evaluated based on its scientific merit and the depth of the study, resulting in 268 cited references and more than 336 illustrative chemical structures carefully selected to support this analysis. As many previous reviews focus on one subclass of this extensive family of compounds, this report represents one of the rare and fully comprehensive assessments of the anticancer potential of this group of molecules across diverse molecular scaffolds.

Small molecule inhibitors of NLRP3 inflammasome and GSK-3β in the management of traumatic brain injury: A review

Traumatic brain injury (TBI) is a debilitating mental condition which causes physical disability and morbidity worldwide. TBI may damage the brain by direct injury that subsequently triggers a series of neuroinflammatory events. The activation of NLRP3 inflammasome and dysregulated host immune system has been documented in various neurological disorders such as TBI, ischemic stroke and multiple sclerosis. The activation of NLRP3 post-TBI increases the production of pro-inflammatory cytokines and caspase-1, which are major drivers of neuroinflammation and apoptosis. Similarly, GSK-3β regulates apoptosis through tyrosine kinase and canonical Wnt signalling pathways. Thus, therapeutic targeting of NLRP3 inflammasome and GSK-3β has emerged as promising strategies for regulating the post-TBI neuroinflammation and neurobehavioral disturbances. In this review, we discuss the identification & development of several structurally diverse and pharmacologically interesting small molecule inhibitors for targeting the NLRP3 inflammasome and GSK-3β in the management of TBI.

AR-A014418, a glycogen synthase kinase-3β inhibitor, mitigates lipopolysaccharide-induced inflammation in rat dental pulp stem cells via NLR family pyrin domain containing 3 inflammasome impairment

Background/purpose

Cell pyroptosis and gingival inflammation have been implicated in periodontitis progression. Our previous study revealed that AR-A014418, a pharmacological inhibitor of glycogen synthase kinase-3β (GSK-3β), can enhance the migratory and osteogenic differentiation abilities of rat dental pulp stem cells (rDPSCs). The present study aimed to explore the effect of AR on the inflammation of rDPSCs.

Materials and methods

The primary rDPSCs were isolated and identified by flow cytometry, as well as Oil red O and Alizarin Red S staining. The rDPSCs were cultured and exposed to lipopolysaccharide (LPS) before treating them with different concentrations of AR-A014418. The cell viability was detected using the CCK-8 assay. The generation and secretion of pro-inflammatory cytokines (IL-18, TNF-α, L-1β, and IL-6) were examined by qPCR and ELISA, respectively. To investigate the activation of the NLRP3 inflammasome, the expression levels of pro-caspase 1, cleaved caspase 1, as well as NLRP3 were analyzed by western blotting and immunofluorescence, respectively.

Results

In the rDPSCs, LPS prohibited cell viability and enhanced the generation and secretion of pro-inflammatory cytokines. LPS upregulated NLRP3 and cleaved caspase-1 protein levels and promoted ASC speck formation in the rDPSCs. AR-A014418 administration effectively blocked the LPS-induced inflammation of the rDPSCs in a dose-dependent way. Mechanistically, AR-A014418 significantly restrained the up-regulation of NLRP3 and cleaved caspase-1 in LPS-treated rDPSCs.

Conclusion

Collectively, our findings suggest that AR-A014418 significantly mitigates LPS-induced inflammation of rDPSCs by blocking the activation of the NLRP3 inflammasome.

Glycogen synthase kinase-3: A potential target for diabetes

Elevated circulating glucose level due to β-cell dysfunction has been a key marker of Type-II diabetes. Glycogen synthase kinase-3 (GSK-3) has been recognized as an enzyme involved in the control of glycogen metabolism. Consequently, inhibitors of GSK-3 have been explored for anti-diabetic effects in vitro and in animal models. Further, the mechanisms governing the regulation of this enzyme have been elucidated by means of a combination of structural and cellular biological investigations. This review article examines the structural analysis of GSK-3 as well as molecular modeling reports from numerous researchers in the context of the design and development of GSK-3 inhibitors. This article centers on the signaling pathway of GSK-3 relevant to its potential as a target for diabetes and discusses advancements till date on different molecular modification approaches used by researchers in the development of novel GSK-3 inhibitors as potential therapeutics for the treatment of Type II diabetes.

Targeted protein degradation might present a novel therapeutic approach in the fight against African trypanosomiasis

African trypanosomiasis (AT) is a hemoparasitic disease caused by infection with African trypanosomes and it is prevalent in many sub-Saharan African countries, affecting both humans and domestic animals. The disease is transmitted mostly by haematophagous insects of the genus Glossina while taking blood meal, in the process spreading the parasites from an infected animal to an uninfected animal. The disease is fatal if untreated, and the available drugs are generally ineffective and resulting in toxicities. Therefore, it is still pertinent to explore novel methods and targets for drug discovery. Proteolysis-targeting chimeras (PROTACs) present a new strategy for development of therapeutic molecules that mimic cellular proteasomal-mediated protein degradation to target proteins involved in different disease types. PROTACs have been used to degrade proteins involved in various cancers, neurodegenerative diseases, and immune disorders with remarkable success. Here, we highlight the problems associated with the current treatments for AT, discuss the concept of PROTACs and associated targeted protein degradation (TPD) approaches, and provide some insights on the future potential for the use of these emerging technologies (PROTACs and TPD) for the development of new generation of anti-Trypanosoma drugs and the first "TrypPROTACs".

Targeting gut-brain axis by dietary flavonoids ameliorate aging-related cognition decline: Evidences and mechanisms

Aging-related cognitive impairment, mainly Alzheimer's disease (AD), has been widely studied. However, effective prevention and treatment methods are still lacking. In recent years, researchers have observed beneficial effects of plant-based supplements, such as flavonoids, on cognitive protection. This provides a new clue for the prevention of cognitive dysfunction. Studies have shown that dietary flavonoids have neuroprotective effects, but the mechanism is not clear. In this review, we systematically reviewed the research progress on the effects of dietary flavonoids on gut microbes and their metabolites, and concluded that flavonoids could improve cognitive function through the gut-brain axis. Flavonoids can be absorbed through the intestine, cross the blood-brain barrier, and enter the brain tissue. Flavonoids can inhibit the expression and secretion of inflammatory factors in brain tissue, reduce the damage caused by oxidative stress, clear neural damage proteins and inhibit neuronal apoptosis, thereby ameliorating age-related cognitive disorders. Future work will continue to explore the gut-brain axis and target genes regulated by flavonoids. In addition, clinical research and its mechanisms need to be further explored to provide solutions or advise for patients with cognitive impairment.

3-Arylidene-2-oxindoles as GSK3β inhibitors and anti-thrombotic agents

Development of novel agents that prevent thrombotic events is an urgent task considering increasing incidence of cardiovascular diseases and coagulopathies that accompany cancer and COVID-19. Enzymatic assay identified novel GSK3β inhibitors in a series of 3-arylidene-2-oxindole derivatives. Considering the putative role of GSK3β in platelet activation, the most active compounds were evaluated for antiplatelet activity and antithrombotic activity. It was found that GSK3β inhibition by 2-oxindoles correlates with inhibition of platelet activation only for compounds 1b and 5a. Albeit, in vitro antiplatelet activity matched well with in vivo anti-thrombosis activity. The most active GSK3β inhibitor 5a exceeds antiplatelet activity of acetylsalicylic acid in vitro by 10.3 times and antithrombotic activity in vivo by 18.7 times (ED₅₀ 7.3 mg/kg). These results support the promising role of GSK3β inhibitors for development of novel antithrombotic agents.

A review on cyclin-dependent kinase 5: An emerging drug target for neurodegenerative diseases

Cyclin-dependent kinase 5 (CDK5) is the serine/threonine-directed kinase mainly found in the brain and plays a significant role in developing the central nervous system. Recent evidence suggests that CDK5 is activated by specific cyclins regulating its expression and activity. P35 and p39 activate CDK5, and their proteolytic degradation produces p25 and p29, which are stable products involved in the hyperphosphorylation of tau protein, a significant hallmark of various neurological diseases. Numerous high-affinity inhibitors of CDK5 have been designed, and some are marketed drugs. Roscovitine, like other drugs, is being used to minimize neurological symptoms. Here, we performed an extensive literature analysis to highlight the role of CDK5 in neurons, synaptic plasticity, DNA damage repair, cell cycle, etc. We have investigated the structural features of CDK5, and their binding mode with the designed inhibitors is discussed in detail to develop attractive strategies in the therapeutic targeting of CDK5 for neurodegenerative diseases. This review provides deeper mechanistic insights into the therapeutic potential of CDK5 inhibitors and their implications in the clinical management of neurodegenerative diseases.

Indirubin Inhibits TRAIL-Induced Activation of Death Receptor 5 in Jurkat Cells

Death receptor 5 (DR5) is an apoptosis-inducing membrane receptor that mediates cell death in several life-threatening conditions. There is a crucial need for the discovery of DR5 antagonists for the therapeutic intervention of conditions in which the overactivation of DR5 underlies the pathophysiology. DR5 activation mediates cell death in non-alcoholic fatty liver disease (NAFLD) and neurodegenerative processes including amyloid-beta (Aβ) accumulation, spinal cord injury (SCI), and brain ischemia. In the current work, we used fluorescence resonance energy transfer (FRET) to monitor the conformational dynamics of DR5 that mediate death signaling. We used a time-resolved FRET screening platform to screen the Selleck library of 2863 U.S. Food and Drug Administration (FDA)-approved compounds. The high-throughput screen (HTS) identified 13 compounds that modulated the FRET between DR5 monomers beyond 5 median absolute deviations (MADs) from the DMSO controls. Of these 13 compounds, indirubin was identified to specifically inhibit tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced caspase-8 activity without modulating DR5 surface expression or TRAIL binding. Indirubin inhibited Fas-associated death domain (FADD) oligomerization and increased cellular FLICE-inhibitory protein (c-FLIP) expression; both are molecular mechanisms involved in inhibiting the DR5 signaling cascade. This study has elucidated previously unknown properties of indirubin that make it a promising candidate for therapeutic investigation of diseases in which overactivation of DR5 underlies pathology.

A Network Pharmacology-Based Study on the Mechanism of Dibutyl Phthalate of Ocimum basilicum L. against Alzheimer's Disease through the AKT/GSK-3β Pathway

Background

Ocimum basilicum L. (OBL) is mainly used to treat neurological diseases in China. The preliminary work of this group showed that OBL improves cognitive impairment in Alzheimer's disease (AD). However, the underlying pharmacological mechanism remains unclear.

Methods

The components of OBL were compiled by literature search, and their active ingredients were screened by online database. The drug targets of OBL in the treatment of AD were predicted and analyzed using information derived from sources such as the SwissTargetPrediction tool. And through the network visual analysis function of Cytoscape software and protein-protein interaction analysis (PPI), the core targets of OBL treatment of AD are predicted. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were employed to analyze the related signaling pathways affected by OBL. Moreover, AutoDock software was used to assess the potential binding affinity between the core targets and the active compounds. Subsequently, in vivo experiment was conducted to verify the findings of network pharmacology.

Results

A total of 35 active compounds and 188 targets of OBL were screened, of which 43 common targets were related to AD. The active compounds of 35 OBLs induced 118 GO and 78 KEGG. The results of PPI and network topology parameter analysis show that targets such as MAPK1, GSK3B, NR3C2, ESR1, and EGFR are known as the core targets for the treatment of AD by OBL and are docked with the active ingredients of OBL. Molecular docking results suggest that diterbutyl phthalate (DBP) may be the main active component of OBL for the treatment of AD. Flow cytometry analysis results showed that apoptosis decreased with increasing DBP dose. In addition, DBP significantly decreased the levels of lactate dehydrogenase (LDH) and reactive oxygen species (ROS) in the supernatant of Aβ _25-35-induced injury HT22 cell cultures, and it can be speculated that DBP has the ability to protect the stability of injured neuronal cells and improve the permeability of cell membranes, thus stabilizing the intracellular environment. Mechanistically, DBP may increase the mRNA levels of AKT, GSK-3β, etc. in AD cell models and regulate the phosphorylation of AKT/GSK-3β pathway-related.

Conclusions

Conclusively, our study suggests that DBP, the main active component of OBL, has potential in the prevention or treatment of AD.

Liangxue Jiedu Runzhi ointment in the treatment of mild and moderate psoriasis with blood-heat syndrome: A double-blind randomized controlled trial

INTRODUCTION

Psoriasis is a kind of chronic inflammatory skin disease characterized by erythema, skin hyperplasia, scales and keratinocyte hyperproliferation. Psoriasis Vulgaris, the most common kind of psoriasis, severely deteriorates the life quality of patients. Traditional Chinese Medicine (TCM) is a good choice for the treatment of psoriasis, which has been proved to be safe and effective, and may reduce the recurrence rate. In clinical practice, Liangxue Jiedu Runzhi (LJR) ointment can effectively treat mild and moderate psoriasis with blood-heat syndrome, but there is a lack of evidence-based medical evidence. This trial aims to evaluate the efficacy and safety of LJR ointment for the treatment of mild and moderate psoriasis with blood-heat syndrome.

METHODS

A multicenter, randomized, double-blind, placebo-controlled, and self-controlled clinical trial was carried out according to this paper. The symmetrical rashes of each subject were regarded as the target lesions and were randomly divided into a treatment group (LJR ointment group) and a control group (placebo group). The LJR ointment or placebo ointment were externally administered on bilateral symmetric rashes, twice a day for eight weeks. The follow-up examination was made for subjects every two weeks. The primary research finding was conveyed by Psoriasis Area and Severity Index (PASI) in 8 weeks. The secondary research finding includes adverse events.

RESULTS

46 subjects undergo this research project. The difference between PASI scores of the target lesions in the treatment group and control group is statistically significant were in 8 weeks (P < .001). The percentage of PASI 75 in treatment group and control group were 48% and 15% in week 8, respectively (x2 = 11.33, P < .05). No severe adverse events were reported.

CONCLUSIONS

LJR ointment was proved to have efficacy in the treatment of mild and moderate psoriasis with the blood-heat syndrome.

Diabetes: Risk factor and translational therapeutic implications for Alzheimer's disease

Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) commonly co-occur. T2DM increases the risk for AD by approximately twofold. Animal models provide one means of interrogating the relationship of T2DM to AD and investigating brain insulin resistance in the pathophysiology of AD. Animal models show that persistent hyperglycaemia results in chronic low-grade inflammation that may contribute to the development of neuroinflammation and accelerate the pathobiology of AD. Epidemiological studies suggest that patients with T2DM who received treatment with specific anti-diabetic agents have a decreased risk for the occurrence of AD and all-cause dementia. Agents such as metformin ameliorate T2DM and may have other important systemic effects that lower the risk of AD. Glucagon-like peptide 1 (GLP-1) agonists have been associated with a decreased risk for AD in patients with T2DM. Both insulin and non-insulin anti-diabetic treatments have been evaluated for the treatment of AD in clinical trials. In most cases, patients included in the trials have clinical features of AD but do not have T2DM. Many of the trials were conducted prior to the use of diagnostic biomarkers for AD. Trials have had a wide range of durations and population sizes. Many of the agents used to treat T2DM do not cross the blood brain barrier, and the effects are posited to occur via lowering of peripheral hyperglycaemia and reduction of peripheral and central inflammation. Clinical trials of anti-diabetic agents to treat AD are ongoing and will provide insight into the therapeutic utility of these agents.

Cdk5-p25 as a key element linking amyloid and tau pathologies in Alzheimer's disease: Mechanisms and possible therapeutic interventions

Despite the fact that the small atypical serine/threonine cyclin-dependent kinase 5 (Cdk5) is expressed in a number of tissues, its activity is restricted to the central nervous system due to the neuron-only localization of its activators p35 and p39. Although its importance for the proper development and function of the brain and its role as a switch between neuronal survival and death are unmistakable and unquestionable, Cdk5 is nevertheless increasingly emerging, as supported by a large number of publications on the subject, as a therapeutic target of choice in the fight against Alzheimer's disease. Thus, its aberrant over activation via the calpain-dependent conversion of p35 into p25 is observed during the pathogenesis of the disease where it leads to the hyperphosphorylation of the β-amyloid precursor protein and tau. The present review highlights the pivotal roles of the hyperactive Cdk5-p25 complex activity in contributing to the development of Alzheimer's disease pathogenesis, with a particular emphasis on the linking function between Aβ and tau that this kinase fulfils and on the fact that Cdk5-p25 is part of a deleterious feed forward loop giving rise to a molecular machinery runaway leading to AD pathogenesis. Additionally, we discuss the advances and challenges related to the possible strategies aimed at specifically inhibiting Cdk5-p25 activity and which could lead to promising anti-AD therapeutics.

Novel effective small-molecule inhibitors of protein kinases related to tau pathology in Alzheimer's disease

Background: Alzheimer's disease (AD) drugs in therapy are limited to acetylcholine esterase inhibitors and memantine. Newly developed drugs against a single target structure have an insufficient effect on symptomatic AD patients. Results: Novel aromatically anellated pyridofuranes have been evaluated for inhibition of AD-relevant protein kinases cdk1, cdk2, gsk-3b and Fyn. Best activities have been found for naphthopyridofuranes with a hydroxyl function as part of the 5-substituent and a hydrogen or halogen substituent in the 8-position. Best results in nanomolar ranges were found for benzopyridofuranes with a 6-hydroxy and a 3-alkoxy substitution or an exclusive 6-alkoxy substituent. Conclusion: First lead compounds were identified inhibiting two to three kinases in nanomolar ranges to be qualified as an innovative approach for AD multitargeting.

Structure-guided engineering of a flavin-containing monooxygenase for the efficient production of indirubin

Indirubin is a bisindole compound for the treatment of chronic myelocytic leukemia. Here, we presented a structure-guided method to improve the activity of a flavin-containing monooxygenase (bFMO) for the efficient production of indirubin in Escherichia coli. A flexible loop interlocked with the active pocket through a helix and the substrate tunnel rather than the active pocket in bFMO were identified to be two reconfigurable structures to improve its activity, resulting in K223R and N291T mutants with enhanced catalytic activity by 2.5- and 2.0-fold, respectively. A combined modification at the two regions (K223R/D317S) achieved a 6.6-fold improvement in catalytic efficiency (kcat/Km) due to enhancing π-π stacking interactions stabilization. Finally, an engineered E. coli strain was constructed by metabolic engineering, which could produce 860.7 mg/L (18 mg/L/h) indirubin, the highest yield ever reported. This work provides new insight into the redesign of FMOs to boost their activities and an efficient approach to produce indirubin.

Dual-target Janus kinase (JAK) inhibitors: Comprehensive review on the JAK-based strategies for treating solid or hematological malignancies and immune-related diseases

Janus kinases (JAKs) are the non-receptor tyrosine kinases covering JAK1, JAK2, JAK3, and TYK2 which regulate signal transductions of hematopoietic cytokines and growth factors to play essential roles in cell growth, survival, and development. Dysregulated JAK activity leading to a constitutively activated signal transducers and activators of transcription (STAT) is strongly associated with immune-related diseases and cancers. Targeting JAK to interfere the signaling of JAK/STAT pathway has achieved quite success in the treatment of these diseases. However, inadequate clinical response and serious adverse events come along by the treatment of monotherapy of JAK inhibitors. With better and deeper understanding of JAK/STAT pathway in the pathogenesis of diseases, researchers start to show huge interest in combining inhibition of JAK and other oncogenic targets to realize a broader regulation on pathological processes to block disease development and progression, which has hastened extensive research of dual JAK inhibitors over the past decades. Until now, studies of dual JAK inhibitors have added BTK, SYK, FLT3, HDAC, Src, and Aurora kinases to the overall inhibitory profile and demonstrated significant advantage and superiority over single-target inhibitors. In this review, we elucidated the possible mechanism of synergic effects caused by dual JAK inhibitors and briefly describe the development of these agents.

Delayed neutrophil apoptosis may enhance NET formation in ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a neutrophil-associated disease. Delayed neutrophil apoptosis and increased levels of neutrophil extracellular traps (NETs) have been described in ARDS. We aimed to investigate the relationship between these phenomena and their potential as inflammation drivers. We hypothesized that delayed neutrophil apoptosis might enhance NET formation in ARDS.

METHOD

Our research was carried out in three aspects: clinical research, animal experiments, and in vitro experiments. First, we compared the difference between neutrophil apoptosis and NET levels in healthy controls and patients with ARDS and analyzed the correlation between neutrophil apoptosis and NET levels in ARDS. Then, we conducted animal experiments to verify the effect of neutrophil apoptosis on NET formation in Lipopolysaccharide-induced acute lung injury (LPS-ALI) mice. Furthermore, this study explored the relationship between neutrophil apoptosis and NETs at the cellular level. Apoptosis was assessed using morphological analysis, flow cytometry, and western blotting. NET formation was determined using immunofluorescence, PicoGreen assay, SYTOX Green staining, and western blotting.

RESULTS

ARDS neutrophils lived longer because of delayed apoptosis, and the cyclin-dependent kinase inhibitor, AT7519, reversed this phenomenon both in ARDS neutrophils and neutrophils in bronchoalveolar lavage fluid (BALF) of LPS-ALI mice. Neutrophils in a medium containing pro-survival factors (LPS or GM-CSF) form more NETs, which can also be reversed by AT7519. Tissue damage can be reduced by promoting neutrophil apoptosis.

CONCLUSIONS

Neutrophils with extended lifespan in ARDS usually enhance NET formation, which aggravates inflammation. Enhancing neutrophil apoptosis in ARDS can reduce the formation of NETs, inhibit inflammation, and consequently alleviate ARDS.

Pathobiology and Therapeutic Relevance of GSK-3 in Chronic Hematological Malignancies

Glycogen synthase kinase-3 (GSK-3) is an evolutionarily conserved, ubiquitously expressed, multifunctional serine/threonine protein kinase involved in the regulation of a variety of physiological processes. GSK-3 comprises two isoforms (α and β) which were originally discovered in 1980 as enzymes involved in glucose metabolism via inhibitory phosphorylation of glycogen synthase. Differently from other proteins kinases, GSK-3 isoforms are constitutively active in resting cells, and their modulation mainly involves inhibition through upstream regulatory networks. In the early 1990s, GSK-3 isoforms were implicated as key players in cancer cell pathobiology. Active GSK-3 facilitates the destruction of multiple oncogenic proteins which include β-catenin and Master regulator of cell cycle entry and proliferative metabolism (c-Myc). Therefore, GSK-3 was initially considered to be a tumor suppressor. Consistently, GSK-3 is often inactivated in cancer cells through dysregulated upstream signaling pathways. However, over the past 10–15 years, a growing number of studies highlighted that in some cancer settings GSK-3 isoforms inhibit tumor suppressing pathways and therefore act as tumor promoters. In this article, we will discuss the multiple and often enigmatic roles played by GSK-3 isoforms in some chronic hematological malignancies (chronic myelogenous leukemia, chronic lymphocytic leukemia, multiple myeloma, and B-cell non-Hodgkin’s lymphomas) which are among the most common blood cancer cell types. We will also summarize possible novel strategies targeting GSK-3 for innovative therapies of these disorders.

PI(18:1/18:1) is a SCD1-derived lipokine that limits stress signaling

Cytotoxic stress activates stress-activated kinases, initiates adaptive mechanisms, including the unfolded protein response (UPR) and autophagy, and induces programmed cell death. Fatty acid unsaturation, controlled by stearoyl-CoA desaturase (SCD)1, prevents cytotoxic stress but the mechanisms are diffuse. Here, we show that 1,2-dioleoyl-sn-glycero-3-phospho-(1’-myo-inositol) [PI(18:1/18:1)] is a SCD1-derived signaling lipid, which inhibits p38 mitogen-activated protein kinase activation, counteracts UPR, endoplasmic reticulum-associated protein degradation, and apoptosis, regulates autophagy, and maintains cell morphology and proliferation. SCD1 expression and the cellular PI(18:1/18:1) proportion decrease during the onset of cell death, thereby repressing protein phosphatase 2 A and enhancing stress signaling. This counter-regulation applies to mechanistically diverse death-inducing conditions and is found in multiple human and mouse cell lines and tissues of Scd1-defective mice. PI(18:1/18:1) ratios reflect stress tolerance in tumorigenesis, chemoresistance, infection, high-fat diet, and immune aging. Together, PI(18:1/18:1) is a lipokine that links fatty acid unsaturation with stress responses, and its depletion evokes stress signaling.

Fatty acid unsaturation by stearoyl-CoA desaturase 1 (SCD1) protects against cellular stress through unclear mechanisms. Here the authors show 1,2-dioleoyl-sn-glycero-3-phospho-(1’-myo-inositol) is an SCD1-derived signaling lipid that regulates stress-adaption, protects against cell death and promotes proliferation.

One-Pot Synthesis of (E)-2-(3-Oxoindolin-2-ylidene)-2-arylacetonitriles

A highly efficient and expeditious one-pot approach towards 2-(3-oxoindolin-2-yl)acetonitriles was designed, which involves a base-assisted aldol reaction of ortho-nitroacetophenones, followed by hydrocyanation, triggering an unusual reductive cyclization reaction.

Oxidative Cyclization of 4-(2-Aminophenyl)-4-oxo-2-phenylbutanenitriles into 2-(3-Oxoindolin-2-ylidene)acetonitriles

A facile and highly efficient method for the preparation of 2-(3-oxoindolin-2-ylidene)acetonitriles from 4-(2-aminophenyl)-4-oxo-2-phenylbutanenitriles is described. The featured transformation operates via nucleophilic intramolecular cyclization and involves oxidation of the aniline moiety. Overall, this modification allowed for the improvement of yields and expansion of the reaction scope.

Advances in Recapitulating Alzheimer's Disease Phenotypes Using Human Induced Pluripotent Stem Cell-Based In Vitro Models

Alzheimer's disease (AD) is an incurable neurodegenerative disorder and the leading cause of death among older individuals. Available treatment strategies only temporarily mitigate symptoms without modifying disease progression. Recent studies revealed the multifaceted neurobiology of AD and shifted the target of drug development. Established animal models of AD are mostly tailored to yield a subset of disease phenotypes, which do not recapitulate the complexity of sporadic late-onset AD, the most common form of the disease. The use of human induced pluripotent stem cells (HiPSCs) offers unique opportunities to fill these gaps. Emerging technology allows the development of disease models that recapitulate a brain-like microenvironment using patient-derived cells. These models retain the individual's unraveled genetic background, yielding clinically relevant disease phenotypes and enabling cost-effective, high-throughput studies for drug discovery. Here, we review the development of various HiPSC-based models to study AD mechanisms and their application in drug discovery.

Glycogen synthase kinase-3β inhibitor promotes the migration and osteogenic differentiation of rat dental pulp stem cells via the β-catenin/PI3K/Akt signaling pathway

Background/purpose

Glycogen synthase kinase-3β (GSK3β) inhibitor enhances bone formation, while dental pulp stem cells (DPSC) are potentially used to repair bone defects. The present study aimed to investigate the effect of AR-A014418 (AR, a specific glycogen synthase kinase-3β inhibitor) on the migration and osteogenic differentiation of rat-derived dental pulp stem cells (rDPSCs), and further explore the underlying mechanism.

Materials and methods

rDPSCs were isolated from rats, and then cultured with different concentrations of AR with or without LY294002 (a PI3K inhibitor). Then, cell viability, migration, osteogenic differentiation, and the involvement of PI3K pathway were detected by CCK-8 assay, Transwell assay, Alizarin Red S Staining, Alkaline phosphatase (ALP) assay, Western blot, and RT-PCR, respectively.

Results

Our present study demonstrated that AR of various concentrations (1 μM, 2.5 μM, and 5 μM) not only promoted the rDPSC proliferation and migration, but also increased calcium deposition, the activity of alkaline phosphatase (ALP), and levels of osteogenic markers (RUNX2, OPN, OCN, and OSX) in rDPSCs. It was also found that the administration of AR resulted in an increase in the expression level of p-GSK3β (Ser), β-catenin, p-PI3K, and p-Akt, and a reduction in p-GSK3β (Tyr216). Furthermore, PI3K inhibitor LY294002 abrogated the enhanced cell migration and osteogenic differentiation of rDPSCs induced by AR.

Conclusion

Our results provide evidence that AR significantly promotes migration and osteogenic differentiation of rDPSCs by activating β-catenin/PI3K/Akt signaling pathway.

Identification of Novel GSK-3β Hits Using Competitive Biophysical Assays

Glycogen synthase kinase 3 beta (GSK-3β) is an evolutionarily conserved serine-threonine kinase dysregulated in numerous pathologies, such as Alzheimer’s disease and cancer. Even though GSK-3β is a validated pharmacological target most of its inhibitors have two main limitations: the lack of selectivity due to the high homology that characterizes the ATP binding site of most kinases, and the toxicity that emerges from GSK-3β complete inhibition which translates into the impairment of the plethora of pathways GSK-3β is involved in. Starting from a 1D ¹⁹F NMR fragment screening, we set up several biophysical assays for the identification of GSK-3β inhibitors capable of binding protein hotspots other than the ATP binding pocket or to the ATP binding pocket, but with an affinity able of competing with a reference binder. A phosphorylation activity assay on a panel of several kinases provided selectivity data that were further rationalized and corroborated by structural information on GSK-3β in complex with the hit compounds. In this study, we identified promising fragments, inhibitors of GSK-3β, while proposing an alternative screening workflow that allows facing the flaws that characterize the most common GSK-3β inhibitors through the identification of selective inhibitors and/or inhibitors able to modulate GSK-3β activity without leading to its complete inhibition.

Discovery of Azaindolin-2-One as a Dual Inhibitor of GSK3β and Tau Aggregation with Potential Neuroprotective Activity

The inhibition of glycogen synthase kinase 3β (GSK3β) activity through pharmacological intervention represents a promising approach for treating challenging neurodegenerative disorders like Alzheimer’s disease. Similarly, abnormal tau aggregate accumulation in neurons is a hallmark of various neurodegenerative diseases. We introduced new dual GSK3β/tau aggregation inhibitors due to the excellent clinical outcome of multitarget drugs. Compound (E)-2f stands out among the synthesized inhibitors as a promising GSK3β inhibitor (IC₅₀ 1.7 µM) with a pronounced tau anti-aggregation effect in a cell-based model of tauopathy. Concurrently, (E)-2f was demonstrated to be non-toxic to normal cells, making it a promising neuroprotective lead compound that needs further investigation.

Bioactivities and Mode of Actions of Dibutyl Phthalates and Nocardamine from Streptomyces sp. H11809

Dibutyl phthalate (DBP) produced by Streptomyces sp. H11809 exerted inhibitory activity against human GSK-3β (Hs GSK-3β) and Plasmodiumfalciparum 3D7 (Pf 3D7) malaria parasites. The current study aimed to determine DBP’s plausible mode of action against Hs GSK-3β and Pf 3D7. Molecular docking analysis indicated that DBP has a higher binding affinity to the substrate-binding site (pocket 2; −6.9 kcal/mol) than the ATP-binding site (pocket 1; −6.1 kcal/mol) of Hs GSK-3β. It was suggested that the esters of DBP play a pivotal role in the inhibition of Hs GSK-3β through the formation of hydrogen bonds with Arg96/Glu97 amino acid residues in pocket 2. Subsequently, an in vitro Hs GSK-3β enzymatic assay revealed that DBP inhibits the activity of Hs GSK-3β via mixed inhibition inhibitory mechanisms, with a moderate IC₅₀ of 2.0 µM. Furthermore, the decrease in K_m value with an increasing DBP concentration suggested that DBP favors binding on free Hs GSK-3β over its substrate-bound state. However, the antimalarial mode of action of DBP remains unknown since the generation of a Pf 3D7 DBP-resistant clone was not successful. Thus, the molecular target of DBP might be indispensable for Pf survival. We also identified nocardamine as another active compound from Streptomyces sp. H11809 chloroform extract. It showed potent antimalarial activity with an IC₅₀ of 1.5 μM, which is ~10-fold more potent than DBP, but with no effect on Hs GSK-3β. The addition of ≥12.5 µM ferric ions into the Pf culture reduced nocardamine antimalarial activity by 90% under in vitro settings. Hence, the iron-chelating ability of nocardamine was shown to starve the parasites from their iron source, eventually inhibiting their growth.

A hybrid approach unveils drug repurposing candidates targeting an Alzheimer pathophysiology mechanism

The high number of failed pre-clinical and clinical studies for compounds targeting Alzheimer disease (AD) has demonstrated that there is a need to reassess existing strategies. Here, we pursue a holistic, mechanism-centric drug repurposing approach combining computational analytics and experimental screening data. Based on this integrative workflow, we identified 77 druggable modifiers of tau phosphorylation (pTau). One of the upstream modulators of pTau, HDAC6, was screened with 5,632 drugs in a tau-specific assay, resulting in the identification of 20 repurposing candidates. Four compounds and their known targets were found to have a link to AD-specific genes. Our approach can be applied to a variety of AD-associated pathophysiological mechanisms to identify more repurposing candidates.

Natural products as novel scaffolds for the design of glycogen synthase kinase 3β inhibitors

INTRODUCTION

The different and relevant roles of GSK-3 are of critical importance since they deal with development, metabolic homeostasis, cell polarity and fate, neuronal growth and differentiation as well as modulation of apoptotic potential. Given their involvement with different diseases, many investigations have been undertaken with the aim of discovering new and promising inhibitors for this target. In this context, atural products represent an invaluable source of active molecules.

AREAS COVERED

In order to overcome issues such as poor pharmacokinetic properties or efficacy, frequently associated with natural compounds, different GSK-3β inhibitors belonging to alkaloid or flavonoid classes have been subjected to structural modifications in order to obtain more potent and safer compounds. Herein, the authors report the results obtained from studies where natural compounds have been used as hits with the aim of providing new kinase inhibitors endowed with a better inhibitory profile.

EXPERT OPINION

Structurally modification of natural scaffolds is a proven approach taking advantage of their pharmacological characteristics. Indeed, whatever the strategy adopted is and, despite the limitations associated with the structural complexity of natural products, the authors recommend the use of natural scaffolds as a promising strategy for the discovery of novel and potent GSK-3β inhibitors.