Base-Promoted [4 + 2] Annulation Reaction of In Situ-Generated Azadienes from N-Propargylamines with Active Methylene Compounds: Access to Highly Functionalized 2-Pyridones

A facile and efficient synthesis of structurally diversified 2-pyridones is demonstrated using the [4 + 2] annulation of in situ generated azadienes from N-propargylamines and active methylene compounds. The reaction is promoted by an inorganic base giving moderate to good yields. The developed methodology is applicable for the direct and formal synthesis of various bioactive molecules. The synthetic utility of the protocol was also illustrated by late-stage functionalization of the products.

Novel quinoxaline-3-propanamides as VGFR-2 inhibitors and apoptosis inducers

Vascular endothelial growth factor receptor-2 is a vital target for therapeutic mediation in various types of cancer. This study was aimed at exploring the cytotoxic activity of seventeen novel quinoxaline-3-propanamides against colon cancer (HCT-116) and breast cancer (MCF-7) using MTT assay. Results revealed that compounds 8, 9, and 14 elicited higher cytotoxicity than the reference drugs, doxorubicin (DOX) and sorafenib. Interestingly, they are more selective for HCT-116 (SI 11.98-19.97) and MCF-7 (SI 12.44-23.87) compared to DOX (SI HCT-116 0.72 and MCF-7 0.9). These compounds effectively reduced vascular endothelial growth factor receptor-2; among them, compound 14 displayed similar VEGFR-2 inhibitory activity to sorafenib (IC50 0.076 M). The ability of 14 to inhibit angiogenesis was demonstrated by a reduction in VEGF-A level compared to control. Furthermore, it induced a significant increase in the percentage of cells at pre-G1 phase by almost 1.38 folds (which could be indicative of apoptosis) and an increase in G2/M by 3.59 folds compared to the control experiment. A flow cytometry assay revealed that compound 14 triggered apoptosis via the programmed cell death and necrotic pathways. Besides, it caused a remarkable increase in apoptotic markers, i.e., caspase-3 p53 and BAX. When compared to the control, significant increase in the expression levels of caspase-3 from 47.88 to 423.10 and p53 from 22.19 to 345.83 pg per ml in MCF-7 cells. As well, it increased the proapoptotic protein BAX by 4.3 times while lowering the antiapoptotic marker BCL2 by 0.45 fold. Docking studies further supported the mechanism, where compound 14 showed good binding to the essential amino acids in the active site of VEGFR-2. Pharmacokinetic properties showed the privilege of these hits over sunitinib: they are not substrates of P-gp protein; this suggests that they have less chance to efflux out of the cell, committing maximum effect; and in addition, they do not allow permeation to the BBB.

Potential role of PIM1 inhibition in the treatment of SARS-CoV-2 infection

BACKGROUND

SARS-CoV-2 infection involves disturbing multiple molecular pathways related to immunity and cellular functions. PIM1 is a serine/threonine-protein kinase found to be involved in the pathogenesis of several viral infections. One PIM1 substrate, Myc, was reported to interact with TMPRSS2, which is crucial for SARS-CoV-2 cell entry. PIM1 inhibitors were reported to have antiviral activity through multiple mechanisms related to immunity and proliferation. This study aimed to evaluate the antiviral activity of 2-pyridone PIM1 inhibitor against SARS-CoV-2 and its potential role in hindering the progression of COVID-19. It also aimed to assess PIM1 inhibitor's effect on the expression of several genes of Notch signaling and Wnt pathways. In vitro study was conducted on Vero-E6 cells infected by SARS-CoV-2 "NRC-03-nhCoV" virus. Protein-protein interaction of the study genes was assessed to evaluate their relation to cell proliferation and immunity. The effect of 2-pyridone PIM1 inhibitor treatment on viral load and mRNA expression of target genes was assessed at three time points.

RESULTS

Treatment with 2-pyridone PIM1 inhibitor showed potential antiviral activity against SARS-CoV-2 (IC50 of 37.255 µg/ml), significantly lowering the viral load. Functional enrichments of the studied genes include negative regulation of growth rate, several biological processes involved in cell proliferation, and Interleukin-4 production, with interleukin-6 as a predicted functional partner. These results suggest an interplay between study genes with relation to cell proliferation and immunity. Following in vitro SARS-CoV-2 infection, Notch pathway genes, CTNNB1, SUMO1, and TDG, were found to be overexpressed compared to uninfected cells. Treatment with 2-pyridone PIM1 inhibitor significantly lowers the expression levels of study genes, restoring Notch1 and BCL9 to the control level while decreasing Notch2 and CTNNB1 below control levels.

CONCLUSION

2-pyridone PIM1 inhibitor could hinder cellular entry of SARS-CoV-2 and modulate several pathways implicated in immunity, suggesting a potential benefit in the development of anti-SARS-CoV-2 therapeutic approach.