Design and Synthesis of Novel Spiropyridine Derivatives as Promising Anti-inflammatory and Gene-targeting Agents Against COVID-19.

BACKGROUND

The COVID-19 pandemic, caused by SARS-CoV-2, has highlighted the urgent need for effective antiviral and anti-inflammatory therapies. Spiropyridine derivatives containing a chalcone moiety have shown potential in targeting key enzymes involved in viral replication and inflammation.

OBJECTIVE

To evaluate the inhibitory effects of synthesized spiropyridine derivatives on SARS-CoV-2 main protease (Mpro), secreted phospholipase A2 (sPLA2), and cytosolic phospholipase A2 (cPLA2), and to assess their impact on inflammatory and oxidative stress markers in LPS-treated lung cells.

AIM: To develop novel therapeutic agents that can effectively manage COVID-19 and related inflammatory conditions.

METHODS

The synthesized compounds (1-3) were tested for their inhibitory activity against SARS-CoV-2 Mpro, sPLA2, and cPLA2 using in vitro assays to determine IC50 values. Inflammatory markers (COX-2, IL-2, IL-4, TGF-1β, TNF-α) and oxidative stress markers (GSH, SOD, GR, MDA) were measured in LPS-treated lung cells. Gene expression levels of sPLA2 and cPLA2 were also assessed. Molecular docking studies were conducted to analyze the binding affinities and interactions of the compounds with the target enzymes.

RESULTS

Compounds 1-3 showed significant inhibitory activity against SARS-CoV-2 Mpro with IC50 values of 19.85 μM, 7.31 μM, and 3.73 μM, respectively. For comparison, baicalein's IC50 value was 13.63 μM. Additionally, these compounds inhibited sPLA2 with IC50 values of 8.36 μM, 7.31 μM, and 3.73 μM, and cPLA2 with IC50 values of 20.44 μM, 6.02 μM, and 4.61 μM, respectively. Baicalein's IC50 values for sPLA2 and cPLA2 were 11.73 μM and 5.89 μM, respectively. In LPS-treated lung cells, compounds 1-3 significantly reduced COX-2 by up to 90.12%, IL-2 by 74.19%, IL-4 by 79.51%, TGF-1β by 44.57%, and TNF-α by 68.49%. They enhanced GSH by up to 194%, SOD by 357.19%, and GR by 445.87%, while reducing MDA by 77.90%. Gene expression of sPLA2 and cPLA2 was significantly downregulated by up to 82.31% and 64.59%, respectively. Molecular docking studies revealed binding affinities of -28.20, -28.20, and -28.07 kcal/mol for SARS-CoV-2 Mpro; -16.72, -17.21, and -15.89 kcal/mol for sPLA2; and -65.66, -66.95, and -79.24 kcal/mol for cPLA2, respectively.

DISCUSSION: The results demonstrate that the structural integration of a spiropyridine core with a chalcone moiety yields compounds with superior multi-target inhibitory activity. The potent antiviral, anti-inflammatory, and antioxidant effects are significantly correlated with their strong binding interactions with the active sites of Mpro, sPLA2, and cPLA2, as validated by molecular docking. These findings align with and extend current research on targeting host-inflammatory pathways alongside viral replication for COVID-19 management.

CONCLUSION

The synthesized spiropyridine derivatives containing a chalcone moiety exhibit potent antiviral, antiinflammatory, and antioxidant properties. These findings suggest that these compounds could be promising therapeutic agents for managing COVID-19 and related inflammatory conditions. Future studies should focus on in vivo experiments, clinical trials, and structural optimization to further develop these compounds for clinical use.