Novel quinoline-based derivatives: A new class of PDE4B inhibitors for adjuvant-induced arthritis

Phosphodiesterase 4B (PDE4B) inhibitors and their applications in recent years (2014 to early 2025)

The phosphodiesterase 4B (PDE4B) subtype, a member of the phosphodiesterase (PDE) family, plays a key role in promoting anti-inflammatory and antifibrotic effects by controlling the rate of cyclic adenosine phosphate degradation. To date, inhibitors targeting PDE4B have been widely used in the development of therapeutic agents for pulmonary fibrosis, inflammation, cancer, Alzheimer's disease, adipose tissue dysfunction and chronic liver injury. With the development of techniques such as molecular docking studies, more and more PDE4B inhibitors with different core scaffolds have been discovered, and at least six of these molecular structures have been approved for marketing or entered clinical studies. In this work, we reviewed the PDE4B inhibitors reported in the literature since 2014 and classified the most representative examples with different biological activities according to their structural characteristics. We also made a preliminary analysis of their structure-activity relationship based on the classification results and the conclusions reported in the relevant literature. In addition, we describe the inhibition selectivity of some compounds to PDE4B and PDE4D enzymes, as inhibition of PDE4D is often associated with side effects such as nausea and emesis. We hope that this work will help researchers in the design and optimization of novel PDE4B selective inhibitors and provide a reference for readers who are new to this field.

COF-SO3H-Catalyzed Synthesis of Pyrazoline-Pyridine Hybrids with Dual Antioxidant and Anti-Inflammatory Activity Targeting PDE4B

This study explores new anti-inflammatory agents by synthesizing pyrazoline-pyridine hybrids with N-butylsulfonated covalent organic framework (COF-SO3H) as a recyclable catalyst, achieving excellent yields in just one minute. The protocol was successfully scaled up to a multi-gram scale, highlighting its robustness and efficiency, and it operates without the need for column chromatography. Among the synthesized hybrids, compound 5d, a pyrazoline-pyridine hybrid bearing an indole moiety, emerged as a potent anti-inflammatory and antioxidant agent. It effectively inhibited PDE4B activation with an IC50 value of 99.38 nM, without adversely affecting HEK cells. Compound 5d demonstrated its dual activity by significantly reducing ROS production and restoring mitochondrial health in LPS-stimulated A549 and HEK cells, while also downregulating IL-1β and NF-ĸB/p65 expression in LPS-stimulated A549 cells. In silico studies confirmed compound 5d's strong binding to PDE4B, with stable RMSD and RMSF values, indicating its potential as a stable and effective PDE4B inhibitor. The compound exhibited favorable physicochemical properties, met drug-likeness criteria, and showed low toxicity as predicted in silico. These findings suggest that compound 5d has significant potential as a therapeutic agent for inflammatory diseases due to its dual anti-inflammatory and antioxidant activities.

2-Trifluoromethyl-2H-chromene ethers: The dual triumph of anti-inflammation and analgesia with minimal ulcer threat

In this report, we disclose the design and synthesis of a series of 2-trifluoromethyl-2H- chromene ethers as novel COX-2 inhibitors with low ulcerogenicity. Among them, 6-fluoro-3-(4-methoxyphenyl)-2-(2-(thiophen-3-yl)ethoxy)-2-(trifluoromethyl)-2H-chromene (E25) significantly suppressed LPS-induced release of NO and PGE2, expression of COX-2 and iNOS, and activation of NF-κB pathway. The inhibitory effect of E25 on human recombinant COX-2 (IC50 = 70.7 ± 4.7 nM) and molecular docking studies suggest that E25 functions as a COX-2 inhibitor. Moreover, the results of the cellular thermal shift assay also substantiate the interaction between E25 and COX-2. E25 manifests potent anti-inflammatory and analgesic efficacy on a par with or even superior to indomethacin in rodent models including carrageenan-induced paw edema, cotton pellet-induced granuloma, acetic acid-induced writhes, and adjuvant-induced arthritis. The possible mechanism of action of E25 might be to bind to COX-2 and suppress the NF-κB pathway as well as the expression of related proteins, thereby exerting anti-inflammatory and analgesic effects. Encouragingly, compared with indomethacin, E25 induces smaller areas and fewer ulcers, a lower level of inflammatory infiltration, a lower expression of MMP-9 and apoptosis of mucosal epithelial cells in rat gastric tissues. Overall, E25 and other analogues are promising candidates worthy of further investigation for the treatment of inflammation and pain, as well as other symptoms in which COX-2 and PGE2 play a role in their etiology.

3-(2-Trifluoromethyl-3-aryl-4H-chromen-4-yl)-1H-indoles: Mastering anti-inflammation and analgesia while mitigating gastrointestinal side effects

A series of 3-(2-trifluoromethyl-3-aryl-4H-chromen-4-yl)-1H-indoles (5-1 to 5-29) were developed and characterized. Most of compounds were found to be potent for inhibiting the production of NO in LPS-induced RAW264.7 cells, of which 3-(3-(4-chlorophenyl)-6-methoxy-2-(trifluoromethyl)-4H-chromen-4-yl)-1H-indole (5-25) was the most optimal (IC50 = 4.82 ± 0.34 μΜ) and was capable of significantly suppressing the release of PGE2. The inhibitory effect of 5-25 on human recombinant COX-2 (IC50 = 51.7 ± 1.3 nM) was measured and molecular docking was performed, determining 5-25 as a COX-2 inhibitor. Additionally, the interaction between 5-25 and COX-2 was determined by the CETSA technique. Then, 5-25 inhibited the degradation of IκB, the phosphorylation and nuclear translocation of NF-κB p65, and the expression of COX-2 and iNOS. Moreover, it was verified that 5-25 exhibited efficacy in rodent models of inflammation and pain, encompassing the paw edema, cotton pellet-induced granuloma, acid-induced writhing, and adjuvant-induced arthritis models. Therefore, the mechanism of 5-25 may be to bind to COX-2 and exert anti-inflammatory and analgesic effects in vitro and in vivo by suppressing the NF-κB pathway. Encouragingly, in comparison with indomethacin, 5-25 exhibited a lower ulcerative potential in rats, as manifested by generating smaller areas and fewer ulcers, less inflammatory infiltration, a lower expression of MMP-9, and less apoptosis. In conclusion, 5-25 is a candidate drug with high activity and low ulcerogenic potential, and it deserves further research for the treatment of inflammation, pain, and other symptoms in which COX-2 plays a role in their pathogenesis.

Discovery of novel CXCR4 inhibitors for the treatment of inflammation by virtual screening and biological evaluation

C-X-C chemokine receptor type 4 (CXCR4) exerts considerable influence on the pathogenesis of inflammatory disorders and offers a potent avenue for drug intervention. This research utilizes a hybrid virtual screening methodology constructed using computer-aided drug design to discover novel CXCR4 inhibitors for the treatment of inflammation. First, a compound library was screened by Lipinski's five rules and adsorption, distribution, metabolism, excretion and toxicity properties. Second, the HypoGen algorithm was used in constructing a 3D-QSAR pharmacophore model and verify it layer by layer, and the obtained optimal pharmacophore 1 (Hypo 1) was used as a 3D query for compound screening. Then, hit compounds were obtained through molecular docking (Libdock and CDOCKER). The toxicity of the compounds to MDA-MB-231 cells was evaluated in vitro, and their binding affinity to the target was evaluated according to how they compete with 12G5 antibody for CXCR4 on the surfaces of the MDA-MB-231 cells. Compound Hit14 showed the strongest binding affinity among the hit compounds and inhibited cell migration and invasion in Matrigel invasion and wound healing assay at a concentration of 100 nM, demonstrating a better effect than AMD3100. Western Blot experiments further showed that Hit14 blocked the CXCR4/CXCL12-mediated phosphorylation of Akt. Meanwhile, cellular thermal displacement assay analysis showed that CXCR4 protein bound to Hit14 had high thermal stability. Finally, through in vivo experiments, we found that Hit14 inhibited mouse ear inflammation and reduced ear swelling and damage. Therefore, Hit14 is a promising drug for the further development of CXCR4 inhibitors for inflammation treatment.

Novel trifluoromethyl ketone derivatives as oral cPLA2/COX-2 dual inhibitors for resolution of inflammation in rheumatoid arthritis

Thirty-five trifluoromethyl hydrazones and seventeen trifluoromethyl oxime esters were designed and synthesized via molecular hybridization. All the target compounds were initially screened for in vitro anti-inflammatory activity by assessing their inhibitory effect on NO release in LPS-stimulated RAW264.7 cells, and the optimal compound was finally identified as 2-(3-Methoxyphenyl)-N'-((6Z,9Z,12Z,15Z)-1,1,1-trifluorohenicosa-6,9,12,15-tetraen-2-ylidene)acetohydrazide (F26, IC50 = 4.55 ± 0.92 μM) with no cytotoxicity. Moreover, F26 potently reduced the production of PGE2 in LPS-stimulated RAW264.7 cells compared to indomethacin. The interaction of F26 with COX-2 and cPLA2 was directly verified by the CETSA technique. F26 was found to modulate the phosphorylation levels of p38 MAPK and NF-κB p65, as well as the protein expression of IκB, cPLA2, COX-2, and iNOS in LPS-stimulated rat peritoneal macrophages. Additionally, F26 was observed to prevent the nuclear translocation of NF-κB p65 in LPS-stimulated rat peritoneal macrophages by immunofluorescence localization. Therefore, the aforementioned in vitro experiments demonstrated that F26 blocked the p38 MAPK and NF-κB pathways by binding to COX-2 and cPLA2. In the adjuvant-induced arthritis model, F26 demonstrated a significant effect in preventing arthritis symptoms and inflammatory status in rats, exerting an immunomodulatory role by regulating the homeostasis between Th17 and Treg through inhibition of the p38 MAPK/cPLA2/COX-2/PGE2 and NF-κB pathways. Encouragingly, F26 caused less acute ulcerogenicity in rats at a dose of 50 mg/kg compared to indomethacin. Overall, F26 is a promising candidate worthy of further investigation for treating inflammation and associated pain with lesser gastrointestinal irritation, as well as other symptoms in which cPLA2 and COX-2 are implicated in the pathophysiology.

Discovery of novel NSAID hybrids as cPLA2/COX-2 dual inhibitors alleviating rheumatoid arthritis via inhibiting p38 MAPK pathway

A series of NSAIDs hybrid molecules were synthesized and characterized, and their ability to inhibit NO release in LPS-induced RAW264.7 macrophages was evaluated. Most of the compounds showed significant anti-inflammatory activity in vitro, of which (2E,6Z,9Z,12Z,15Z)-1,1,1-trifluorohenicosa-2,6,9,12,15-pentaen-2-yl 2-(4-benzoylphenyl) propanoate (VI-60) was the most optimal (IC50 = 3.85 ± 0.25 μΜ) and had no cytotoxicity. In addition, VI-60 notably reduced the production of PGE2 in LPS-stimulated RAW264.7 cells compared to ketoprofen. Futhur more, VI-60 significantly inhibited the expression of iNOS, cPLA2, and COX-2 and the phosphorylation of p38 MAPK in LPS-stimulated RAW264.7 cells. The binding of VI-60 to cPLA2 and COX-2 was directly verified by the CETSA technique. In vivo studies illustrated that VI-60 exerted an excellent therapeutic effect on adjuvant-induced arthritis in rats by regulating the balance between Th17 and Treg through inhibiting the p38 MAPK/cPLA2/COX-2/PGE2 pathway. Encouragingly, VI-60 showed a lower ulcerative potential in rats at a dose of 50 mg/kg compared to ketoprofen. In conclusion, the hybrid molecules of NSAIDs and trifluoromethyl enols are promising candidates worthy of further investigation for the treatment of inflammation, pain, and other symptoms in which cPLA2 and COX-2 play a role in their etiology.

f25, a novel synthetic quinoline derivative, inhibits tongue cancer cell invasion and survival by the PPAR pathway in vitro and vivo

Tongue cancer has a very high incidence in China, and there is a need to develop new anti-tumour drugs against it. We synthesised 31 novel quinoline derivatives to test their anti-tumour activity. A compound referred to as "f25" was identified through screening for its high in vitro toxicity against an oral squamous carcinoma cell line (CAL-27). f25 exhibited significant cytotoxicity against CAL-27 cells (IC50 = 7.70 ± 0.58 μΜ). f25 also inhibited the migration and invasion of CAL-27 cells to a level comparable with that of the chemotherapy agent cisplatin. Moreover, f25 promoted the apoptosis of CAL-27 cells. Transcriptome sequencing and western blotting showed that the mechanism of action of f25 against CAL-27 cells involved the peroxisome proliferator-activated receptor (PPAR) signalling pathway. Specifically, f25 could bind to PPAR-α, PPAR-β, and PPAR-γ and increase their expression. In vivo experiments showed that treatment with f25 led to a reduction in tumour volume in nude mice without significant toxicity. Overall, this study highlights the potential of quinoline compounds (particularly f25) for the design and synthesis of anti-tumour drugs. It also underscores the importance of the PPAR signalling pathway as a target for potential cancer therapies.

Discovery of novel deoxyvasicinone derivatives with benzenesulfonamide substituents as multifunctional agents against Alzheimer's disease

A series of deoxyvasicinone derivatives with benzenesulfonamide substituents were designed and synthesized to find a multifunctional anti-Alzheimer's disease (AD) drug. The results of the biological activity evaluation indicated that most compounds demonstrated selective inhibition of acetylcholinesterase (AChE). Among them, g17 exhibited the most potent inhibitory effect on AChE (IC50 = 0.24 ± 0.04 μM). Additionally, g17 exhibited promising properties as a metal chelator and inhibitor of amyloid β peptides self-aggregation (68.34 % ± 1.16 %). Research on oxidative stress has shown that g17 displays neuroprotective effects and effectively suppresses the intracellular accumulation of reactive oxygen species. Besides, g17 demonstrated remarkable anti-neuroinflammatory effects by significantly reducing the production of pro-inflammatory cytokines (such as NO, IL-1β, and TNF-α) and inhibiting the expression of inflammatory mediators iNOS and COX-2. In vivo studies showed that g17 significantly improved AD model mice's cognitive and memory abilities. Histological examination of mouse hippocampal tissue sections using hematoxylin and eosin staining revealed that g17 effectively mitigates neuronal damage. Considering the multifunctional properties of g17, it is regarded as a promising lead compound for treating AD.

Anti-inflammatory effect of glycyrrhetinic acid in IL-1β-induced SW982 cells and adjuvant-induced arthritis

Influences of Glycyrrhetinic acid on expression of inflammatory factors in interleukin (IL)-1β-induced SW982 cells and its anti-inflammatory effects were discussed in this study. MTT results showed that Glycyrrhetinic acid (≤80 μmol·L-1) almost has no toxicity on SW982 cells. The results of ELISA and real-time PCR showed that Glycyrrhetinic acid (10, 20 and 40 μmol · L-1) can significantly inhibit the expression of inflammatory factors such as IL-6, IL-8 and matrix metalloproteinase-1 (MMP-1). Western blot analysis showed that Glycyrrhetinic acid remarkably blocked the NF-κB signaling pathway in vitro. Molecule docking showed that Glycyrrhetinic acid could bind to the active site (NLS Polypeptide) of NF-κB p65. Furthermore, observation of rat foot swelling proved that Glycyrrhetinic acid had a significant therapeutic effect on adjuvant-induced arthritis (AIA) in rats in vivo. Collectively, all these findings suggested that Glycyrrhetinic acid might be a promising lead compound worthy of further pursuit as anti-inflammation agent.