Isolation and in silico SARS-CoV-2 main protease inhibition potential of chrysoeriol from Chondrilla brevirostris Fisch. & C.A.Mey.

The genus Chondrilla L. comprises 22 species on the CIS territory. 16 species of them grow in Kazakhstan. All species of the genus Chondrilla L. are rubber-bearing herbaceous plants that belong to the Asteraceae family. We picked Chondrilla brevirostris Fisch. & C.A. Mey. for the chemical study. It is a perennial herb that grows in desert steppes and forest meadows. The aboveground parts of Ch. brevirostris were extracted with ethanol at room temperature. Several fractions were obtained by separating ethanol extract on column chromatography. Rechromatography and preparative thin-layer chromatography were used to further study the obtained fractions and the isolation of flavonoids. As a result of preparative thin-layer chromatography, the flavonoid 5,7,4'-trihydroxy-3'-methoxyflavone (compound 1) was isolated. The chemical structure of 1 was established by spectroscopic data. Compound 1 was isolated for the first time from the species of Chondrilla. Compound 1 was subjected to a molecular docking study against COVID-19 main protease (M-pro) to investigate its expected activity against SARS-CoV-2. In this case, the substance showed a good binding mode with a free energy of -6.22 kcal/mol, while the binding energy of the co-crystallized ligand was -7.83 kcal/mol.