Design, Synthesis, In vitro and In vivo Evaluation of New Imidazo[1,2-a]pyridine Derivatives as Cyclooxygenase-2 Inhibitors

BACKGROUND

Cyclooxygenase-2 (COX-2), the key enzyme in the arachidonic acid conversion to prostaglandins, is one of the enzymes associated with different pathophysiological conditions, such as inflammation, cancers, Alzheimer's, and Parkinson's disease. Therefore, COX-2 inhibitors have emerged as potential therapeutic agents in these diseases.

OBJECTIVE

The objective of this study was to design and synthesize novel imidazo[1,2-a]pyridine derivatives utilizing rational design methods with the specific aim of developing new potent COX-2 inhibitors. Additionally, we sought to investigate the biological activities of these compounds, focusing on their COX-2 inhibitory effects, analgesic activity, and antiplatelet potential. We aimed to contribute to the development of selective COX-2 inhibitors with enhanced therapeutic benefits.

METHODS

Docking investigations were carried out using AutoDock Vina software to analyze the interaction of designed compounds. A total of 15 synthesized derivatives were obtained through a series of five reaction steps. The COX-2 inhibitory activities were assessed using the fluorescent Cayman kit, while analgesic effects were determined through writing tests, and Born's method was employed to evaluate antiplatelet activities.

RESULTS

The findings indicated that the majority of the tested compounds exhibited significant and specific inhibitory effects on COX-2, with a selectivity index ranging from 51.3 to 897.1 and IC50 values of 0.13 to 0.05 μM. Among the studied compounds, derivatives 5e, 5f, and 5j demonstrated the highest potency with IC50 value of 0.05 μM, while compound 5i exhibited the highest selectivity with a selectivity index of 897.19. In vivo analgesic activity of the most potent COX-2 inhibitors revealed that 3-(4-chlorophenoxy)-2-[4-(methylsulfonyl) phenyl] imidazo[1,2-a]pyridine (5j) possessed the most notable analgesic activity with ED50 value of 12.38 mg/kg. Moreover, evaluating the antiplatelet activity showed compound 5a as the most potent for inhibiting arachidonic acidinduced platelet aggregation. In molecular modeling studies, methylsulfonyl pharmacophore was found to be inserted in the secondary pocket of the COX-2 active site, where it formed hydrogen bonds with Arg-513 and His-90.

CONCLUSION

The majority of the compounds examined demonstrated selectivity and potency as inhibitors of COX-2. Furthermore, the analgesic effects observed of potent compounds can be attributed to the inhibition of the cyclooxygenase enzyme.

The Anticancer Effects of Novel Imidazo[1,2-a]Pyridine Compounds against HCC1937 Breast Cancer Cells

BACKGROUND

Anticancer drugs confront clinical obstacles such as drug resistance and adverse effects. Imidazo[1,2-a]pyridines (IPs) compounds have lately gained considerable interest as possible anticancer therapeutics due to their potent inhibitory function against cancers cells. This study was to determine the anticancer activities of three novel IPs (IP-5, IP-6, and IP-7) against the HCC1937 breast cancer cell line in vitro.

MATERIALS AND METHODS

The cytotoxic and anti-proliferative effects of IPs compounds in HCC1937 cells were determined by cell viability (MTT) assay, trypan blue assay, and clonogenic survival assay. Scratch motility assay was used to test the antimigration ability of the IPs. Western blot analysis was carried out to detect the level of apoptosis and cell cycle protein markers and to understand the mechanism of action of IPs compounds.

RESULTS

IP-5 and IP-6 have a strong cytotoxic impact against HCC1937 cells with IC50 values of 45µM and 47.7µM respectively. IP-7 possesses less cytotoxic effect against HCC1937 cells with IC50 of 79.6µM. Trypan blue assay showed that the three compounds induce significant cell death in the HCC1937 cells. Clonogenic and mammosphere assays demonstrated that IP-5 reduced the HCC1937 cells survival rate by more than 25.0% at 1000 cell concentrations. Western blotting analysis showed that IP-5 compound causes cell cycle arrest as noted by the increasing levels of p53 and p21 in treated cells. IP-5 induced an extrinsic apoptosis pathway as reveals from the increased activity of caspase 7, caspase 8, and the increasing level of PARP cleavage in treated cells. Also, IP-5 treated cells revealed segmented chromatin which is characteristic of apoptotic cells as shown by DAPI stain. Importantly, In comparison to control cells, IP-5-treated cells exhibited lower levels of pAKT.

CONCLUSIONS

The novel three IPs compounds represent potential active anticancer compounds against HCC1937 breast cancer cells in vitro.

Rational design, optimization, and biological evaluation of novel α-Phosphonopropionic acids as covalent inhibitors of Rab geranylgeranyl transferase

Rab geranylgeranyltransferase (GGTase-II, RGGT) catalyses the post-translational modification of eukaryotic Rab GTPases, proteins implicated in several pathologies, including cancer, diabetes, neurodegenerative, and infectious diseases. Thus, RGGT inhibitors are believed to be a potential platform for the development of drugs and tools for studying processes related to the abnormal activity of Rab GTPases. Here, a series of new α-phosphonocarboxylates have been prepared in the first attempt of rational design of covalent inhibitors of RGGT derived from non-covalent inhibitors. These compounds were equipped with electrophilic groups capable of binding cysteines, which are present in the catalytic cavity of RGGT. A few of these analogues have shown micromolar activity against RGGT, which correlated with their ability to inhibit the proliferation of the HeLa cancer cell line. The proposed mechanism of this inhibitory activity was rationalised by molecular docking and mass spectrometric measurements, supported by stability and reactivity studies.

Aminoimidazo[1,2-a]pyridine Bearing Different Pyrazole Moieties as the Structural Scaffold for the Development of BACE1 Inhibitor; Synthesis, Structural Characterization, In vitro and In silico Studies

Regarding the critical role of amyloid-β plaques on the pathogenesis of Alzheimer's disease, a series of aminoimidazo[1,2-a]pyridine derivatives was designed and synthesized as potential anti-BACE1 agents targeting the production of amyloid-β plaques. In vitro, biological results demonstrated that compounds 7b and 7f exhibited the best inhibitory potency against BACE1 with IC50 values of 22.48 ± 2.06 and 30.61 ± 3.48 μM, respectively. Also, the ligand-protein docking evaluations revealed that compounds 7b and 7f could effectively bind with the different pockets of BACE1 through different interactions with the residue of the active site. The results of current studies underline the potential role of aminoimidazo[1,2-a] pyridine-containing pyrazole derivatives for developing novel BACE1 inhibitors.

A Novel Imidazo[1,2-a]pyridine Compound Reduces Cell Viability and Induces Apoptosis of HeLa Cells by p53/Bax-Mediated Activation of Mitochondrial Pathway

BACKGROUND

Despite emerging research on new treatment strategies, chemotherapy remains one of the most important therapeutic modalities for cancers. Imidazopyridines are important targets in organic chemistry and are worthy of attention given their numerous applications.

OBJECTIVE

To design and synthesize a novel series of imidazo[1,2-a]pyridine-derived compounds and investigate their antitumor effects and the underlying mechanisms.

METHODS

Imidazo[1,2-a]pyridine-derived compounds were synthesized with new strategies and conventional methods. The antitumor activities of the new compounds were evaluated by MTT assay. Flow cytometry and immunofluorescence were performed to examine the effects of the most effective antiproliferative compound on cell apoptosis. Western blot analysis was used to assess the expression of apoptotic proteins.

RESULTS

Fifty-two new imidazo[1,2-a]pyridine compounds were designed and successfully synthesized. The compound, 1-(imidazo[1,2-a]pyridin-3-yl)-2-(naphthalen-2-yl)ethane-1,2-dione, named La23, showed high potential for suppressing the viability of HeLa cells (IC50 15.32 μM). La23 inhibited cell proliferation by inducing cell apoptosis, and it reduced the mitochondrial membrane potential of HeLa cells. Moreover, treatment with La23 appeared to increase the expression of apoptotic-related protein P53, Bax, cleaved caspase-3, and cytochrome c at a low concentration range.

CONCLUSION

The novel imidazo[1,2-a]pyridine compound, La23, was synthesized and suppressed cell growth by inducing cell apoptosis via the p53/Bax mitochondrial apoptotic pathway.