Discovery of cinnamoyl–flavonoid hybrid derivatives as inhibitors of SARS-CoV-2 Mpro and anti-inflammatory agents: Experimental and in silico insights into their efficacy against lipopolysaccharide-induced lung injury

Abstract

The chemical structures of the parental compounds of flavonoids from Boesenbergia rotunda were modified by conjugation with cinnamic acid to form cinnamoyl–flavonoid hybrid derivatives with enhanced anti-inflammatory and SARS-CoV-2 M^pro-inhibitory properties. Cinnamoyl–flavonoid hybrid derivatives 6 and 10 showed the potential to inhibit SARS-CoV-2 M^pro with IC₅₀ values of 52.49 and 22.62 μM. Compounds 6 and 10 showed lower cytotoxicity in the human lung cell lines MRC-5 and A549 at concentrations greater than 50 μM. The effects of compounds 6 and 10 on cell viability were studied in a 3D co-culture model of A549 and MRC-5 treated with lipopolysaccharide (LPS) and observed through confocal microscopy. Compounds 6 and 10 downregulated p65 mRNA expression, resulting in a reduction of pro-inflammatory cytokines, including Interleukin 8 (IL-8) and Monocyte Chemoattractant Protein-1 (MCP-1/CCL2), leading to an anti-inflammatory response through Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signalling pathways. Compound 6 showed potential anti-inflammatory activity, downregulating Bcl-2 Associated X gene (BAX), which resulted in inhibition of apoptotic cell death when compared to compound 10. In silico molecular dynamic simulation shed light on how these cinnamoyl–flavonoid hybrid derivatives interact with myeloid differentiation factor 2 (MD-2), which is involved in the inflammatory response. Our findings suggest that cinnamoyl–flavonoid hybrid derivatives show potential as anti-inflammatory drugs and anti-SARS-CoV-2 drugs.