Three new C21steroidal glycosides isolated fromMetaplexis japonicaand their potential inhibitory effects on tyrosine protein kinases

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Three new steroidal glycosides, metapregnoside A–C (II–IV), together with one known compound, byzantionoside B (I), were isolated from the fresh whole herb of Metaplexis japonica by using high-speed countercurrent chromatography and semi-preparative liquid chromatography. Their structures and relative configurations were elucidated by spectroscopic methods including 1D NMR, 2D NMR and HR-ESI-MS. The potential targets of compound I–IV were identified by virtual screening. And the potential inhibitory effects of these compounds on tyrosine protein kinases were compared by molecular docking. Byzantionoside B (I) was the first isolated compound from Metaplexis genus. The docking score of metapregnoside C (IV) was the highest. And the sugar chain residues at position C-20 in the pregn-4-en-3-one derivatives is the main factor affecting their docking scores on tyrosine protein kinases Fes/Fps.