Alkaloid constituents from Viola tianschanica.

Eighteen previously undescribed alkaloids, tishaviolamines A-J, including eight pairs of enantiomers, together with two known benzylisoquinoline alkaloids, (-)-bicuculline and (-)-corlumine, were isolated from Viola tianschanica. Among them, tishaviolamine A-E were demonstrated to possess three types of unpresented skeletons. The structures of these alkaloids were established by comprehensive analyses of the 1D, 2D-NMR and (+)HRESIMS data. The absolute configurations of enantiomers were determined by comparing their calculated ECD spectra with the experimental ones. The menin-mixed lineage leukemia 1 protein-protein interaction inhibitory effect of the isolated compounds were also measured.