Structure-based design of benzo[e]isoindole-1,3-dione derivatives as selective GSK-3β inhibitors to activate Wnt/β-catenin pathway

Ruthenium(II)-Catalyzed Annulation of Oximes with Maleimides: Synthesis of Pyrrolo[3,4-c]isoquinoline-1,3-diones

A series of pyrroloisoquinoline-1,3-diones has been synthesized using ruthenium(II) as the catalyst and oxygen as the oxidant in a straightforward manner. The reaction proceeds through a tandem C-C/C-N bond formation process between maleimides and ketoximes, providing a direct approach for the synthesis of the titled products. This operationally simple reaction procedure supplies suitable conditions for synthesizing diverse isoquinoline-based heterocycles with a range of functional groups in moderate to good yields and compatible with gram-scale synthesis. Furthermore, the compatibility of this reaction with oxygen as a green and environmentally friendly oxidant raises the importance of the present method.

Ru(II)-Catalyzed C-H Activation/[4+2] Annulation of Sulfoxonium Ylide with Maleimide: Access to Fused Benzo[e]isoindole-1,3,5-trione

A ruthenium-catalyzed C-H activation and a concomitant [4+2] annulation of sulfoxonium ylide with maleimide have been demonstrated. This tandem reaction results in the formation of fused benzo[e]isoindole-1,3,5-trione. The method employs mild conditions and is free of metal oxidants. The reaction pathway predominantly involves protodemetalation over β-hydride elimination due to the lack of syn β-hydrogens.

Impact of GSK-3β and CK-1δ on Wnt signaling pathway in alzheimer disease: A dual target approach

Alzheimer's disease (AD) is an enigmatic neurological illness that offers few treatment options. Recent exploration has highlighted the crucial connection of the Wnt signaling pathway in AD pathogenesis, shedding light on potential therapeutic targets. The present study focuses on the dual targeting of glycogen synthase kinase-3β (GSK-3β) and casein kinase-1δ (CK-1δ) within the framework of the Wnt signaling pathway as a possible technique for AD intervention. GSK-3β and CK-1δ are multifunctional kinases known for their roles in tau hyperphosphorylation, amyloid processing, and synaptic dysfunction, all of which are major hallmarks of Alzheimer's disease. They are intricately linked to Wnt signaling, which plays a pivotal part in sustaining neuronal function and synaptic plasticity. Dysregulation of the Wnt pathway in AD contributes to cognitive decline and neurodegeneration. This review delves into the molecular mechanisms by which GSK-3β and CK-1δ impact the Wnt signaling pathway, elucidating their roles in AD pathogenesis. We discuss the potential of small-molecule inhibitors along with their SAR studies along with the multi-targetd approach targeting GSK-3β and CK-1δ to modulate Wnt signaling and mitigate AD-related pathology. In summary, the dual targeting of GSK-3β and CK-1δ within the framework of the Wnt signaling pathway presents an innovative and promising avenue for future AD therapies, offering new hope for patients and caregivers in the quest to combat this challenging condition.

Rh-Catalyzed Annulation of Enaminones with Maleimides for Functionalized Aza-spiro α-Tetralones and Benzo[e]isoindoles via C-H Activation/C═C Bond Cleavage

An unprecedented strategy for Rh-catalyzed C-H activation/C═C bond cleavage of enaminones is described for the construction of biologically interesting aza-spiro α-tetralones and benzo[e]isoindoles. This protocol provides diversely functionalized aza-spiro α-tetralones and benzo[e]isoindoles in good yields via a [4 + 2] annulation of the exomaleimides and maleimides. This strategy displays a good substrate scope, outstanding functional group tolerance, and excellent regioselectivity.

Unexpected Cascade Sequence Forming the C(sp3)-N/C(sp2)-C(sp2) Bond: Direct Access to γ-Lactam-Fused Pyridones with Anticancer Activity

An unexpected Ugi cascade reaction was developed for the facile construction of γ-lactam-fused pyridone derivatives with high tolerance of substrates. A C(sp3)-N bond and a C(sp2)-C(sp2) bond were formed together, accompanied by a chromone ring-opening in Ugi adducts, under the basic conditions without any metal catalyst for the whole process. Screening data of several difficult-to-inhibit cancer cell lines demonstrated that 7l displayed a high cytotoxicity against HCT116 cells (IC50 = 5.59 ± 0.78 μM). Taken together, our findings revealed new insights into the molecular mechanisms underlying compound 7l and provided potential usage of this scaffold for cancer therapeutics.

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.

OGDHL ameliorates cognitive impairment and Alzheimer's disease-like pathology via activating Wnt/β-catenin signaling in Alzheimer's disease mice

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases related to several types of pathophysiological signs, including β-amyloid (Aβ) plaque accumulation, neuroinflammation, and neurofibrillary tangles. Similar to one of the three subunits of α-ketoglutarate dehydrogenase complex (KGDHC), oxoglutarate dehydrogenase-like (OGDHL) appears to be downregulated in triple-transgenic Alzheimer's (3 × Tg-AD) mice. KGDHC activity is specifically reduced in the brains of people with AD. However, the underlying mechanism of OGDHL in the cause of AD is still unknown. Herein, we confirmed the low expression of OGDHL in the brain of 3 × Tg-AD based on real-time quantitative PCR, Western blot, and immunohistochemistry. We also found that the upregulation of OGDHL can reduce the memory deficits of 3 × Tg-AD mice, thereby reminding its nervous system neuroprotective effect in AD. Next, we confirmed that the increase in OGDHL could reduce neuroinflammation, amyloid plaque load, and tau phosphorylation in 3 × Tg-AD mice. Additionally, we showed that the overexpression of OGDHL could activate Wnt/β-catenin signaling based on the expression of Wnt7B in vitro. Taken together, the results show that the rise of OGDHL reasonably improves the cognitive functions according to the activation of the Wnt/β-catenin signaling pathway. Therefore, this enzyme may be a potential strategy for AD treatment.

Synthesis of maleimide fused benzocarbazoles and imidazo[1,2-a]pyridines via rhodium(iii)-catalyzed [4 + 2] oxidative cycloaddition

In this paper, an efficient and sustainable synthesis of maleimide-fused benzocarbazoles/imidazo[1,2-a]pyridines from the reaction of 2-arylindoles/2-arylimidazo[1,2-a]pyridines with maleimides through oxidative [4 + 2] annulation is presented.

Synthesis and biological evaluation of 3-substituted 2-oxindole derivatives as new glycogen synthase kinase 3β inhibitors

Glycogen synthase kinase 3β (GSK-3β) is a widely investigated molecular target for numerous diseases including Alzheimer's disease, cancer, and diabetes mellitus. Inhibition of GSK-3β activity has become an attractive approach for treatment of diabetes and cancer. We report the discovery of novel GSK-3β inhibitors of 3-arylidene-2-oxindole scaffold with promising activity. The most potent compound 3a inhibits GSK-3β with IC₅₀ 4.19 nM. In a cell-based assay 3a shows no significant leucocyte toxicity at 10 µM and is moderately cytotoxic against A549 cells. Compound 3a demonstrated high antidiabetic efficacy in obese streptozotocin-treated rats improving glucose tolerance at a dose of 50 mg/kg body weight thus representing an interesting lead for further optimization.

Structure-activity relationship (SAR) studies of synthetic glycogen synthase kinase-3β inhibitors: A critical review

Glycogen Synthase Kinase-3 (GSK-3) is a constitutively dynamic, omnipresent serine/threonine protein kinase regularly called as a "multitasking kinase" due to its pliable function in diverse signaling pathways. It exists in two isoforms i.e., GSK-3α and GSK-3β. Inhibition of GSK-3 may be useful in curing various diseases such as Alzheimer's disease, type II diabetes, mood disorders, cancers, chronic inflammatory agents, stroke, bipolar disorders and so on, but the approach poses significant challenges. Lithium was the first GSK-3β inhibitor to be used for therapeutic outcome and has been effectively used for many years. In recent years, a large number of structurally diverse potent GSK-3β inhibitors are reported. The present review focuses on the recent developments in the area of medicinal chemistry to explore the diverse chemical structures of potent GSK-3β inhibitors and also describes its structure-activity relationships (SAR) and molecular binding interactions of favorable applicability in various diseases.

Zearalenone-Promoted Follicle Growth through Modulation of Wnt-1/β-Catenin Signaling Pathway and Expression of Estrogen Receptor Genes in Ovaries of Postweaning Piglets

Feedstuffs are severely contaminated by zearalenone (ZEA) worldwide. A specific dietary level of ZEA could cause malformations of the reproductive organs of sows, false estrus, decreased litter size, and abortion. However, the underlying mechanisms are still not clear. The objectives of the present study were to assess the effects of ZEA on morphology, distribution, and expression of estrogen receptors (ERα and ERβ) in the ovaries of postweaning piglets. Furthermore, the relationship between ERs/glycogen synthase kinase (GSK)-3β-dependent pathways mediated by ZEA and the Wnt-1/β-catenin signaling pathway was examined. Forty healthy weaning piglets were allocated to the following four treatment groups: piglets fed with basal diet only (control), and ZEA0.5, ZEA1.0, and ZEA1.5, which were fed basal diets supplemented with ZEA at 0.5, 1.0, and 1.5 mg·kg^-1, respectively. Then, the expression of GSK-3β, ERα, ERβ, and Wnt-1/β-catenin were examined histomorphologically and immunohistochemically. Results showed that the proportion of primordial follicles (PrF's) decreased ( p < 0.001) but that of atretic primordial follicles (APFs) increased ( p < 0.001) with increasing dietary ZEA levels. More interestingly, the immunopositivity of ERβ in the ovaries was stronger than that of ERα with the same treatment. The relative mRNA and protein expression levels of ERα, ERβ, Wnt-1, β-catenin, and GSK-3β in the ovaries of postweaning gilts increased linearly ( p < 0.05) as dietary ZEA concentrations increased. Moreover, the accumulation of Wnt-1 and β-catenin in the ovaries indicated that ZEA activated the Wnt-1/β-catenin pathway, mediated by ERs/GSK-3β. Our results strongly suggested that ovarian follicles in the ZEA (0.5-1.5 mg·kg^-1)-treated groups were highly proliferative state, indicating that ZEA promoted ovarian development. The results also suggested that ZEA activates the ERs/GSK-3β-dependent Wnt-1/β-catenin signaling pathway, indicating its important role in accelerating development of the ovaries.

Design and synthesis of (aza)indolyl maleimide-based covalent inhibitors of glycogen synthase kinase 3β

The optimization of both non-covalent interactions and reactive groups led to azaindolyl maleimide compound 38b as a selective and covalent inhibitor against GSK3β.

Glycogen synthase kinase-3 and its inhibitors: Potential target for various therapeutic conditions

Glycogen Synthase Kinase-3 (GSK-3) is a serine/threonine kinase which is ubiquitously expressed and is regarded as a regulator for various cellular events and signalling pathways. It exists in two isoforms, GSK-3α and GSK-3β and can phosphorylate a wide range of substrates. Aberrancy in the GSK-3 activity can lead to various diseases like Alzheimer's, diabetes, cancer, neurodegeneration etc., rendering it an attractive target to develop potent and specific inhibitors. The present review focuses on the recent developments in the area of GSK-3 inhibitors and also enlightens its therapeutic applicability in various disease conditions.