Investigation of embelin synthetic hybrids as potential COVID-19 and COX inhibitors: Synthesis, spectral analysis, DFT calculations and molecular docking studies

Embelin (2, 5-dihydroxy-3-undecyl-1,4-benzoquinone), a benzoquinone isolated from fruits of Embelia ribes has miscellaneous biological potentials including; anticancer, anti-inflammation, antibiotic, and anti-hyperglycemic activities. Also, embelin down-regulates the overexpression of inflammatory pathways like NF-kB, TACE, TNF-α, and other cytokines. Furthermore, embelin fascinated synthetic interest as a pharmacologically active compound. The present article involves the design, synthesis, DFT calculations, and molecular docking studies of embelin derivatives as cyclooxygenase inhibitors. The structure of these derivatives is confirmed by the various spectral analyses such as IR, NMR, and Mass. The DFT calculations were carried out for the molecules (1-8) using CAM-B3LYP hybrid functional with a 6-31+g(d) all-electron basis set using the Gaussian 09 package. Second-order harmonic vibrational calculations are used to check the minimum nature of the geometry. Further, HOMO and LUMO analyses were used for the charge transfer interface between the structures. Based on our previous work and structural activity relationship study, foresaid embelin derivatives were evaluated for in vitro COX-1 and COX-2 inhibitory activity. The compounds 3, 4, 7, and 8 demonstrated excellent COX inhibitions with IC50 values of 1.65, 1.54, 1.56, and 1.23 μM compared to standard drugs Celecoxib and Ibuprofen. Finally, the molecular docking studies carried out with Covid-19 and cyclooxygenase with all the newly synthesized embelin derivatives.