Aporphine alkaloids and flavonoids from the roots of Fissistigma retusum (H. Lév.) Rehder

A new aporphine alkaloid, (R)-1,2-methylenedioxy-8-methoxy-9-hydroxynoraporphine (1), two new flavonoids, (S)-6,8-dihydroxy-7-methoxyflavanone (7) and (S)-6,8-dihydroxy-5,7-dimethoxyflavanone (8), along with seven known compounds, were isolated from the roots of Fissistigma retusum (H. Lév.) Rehder. Structural determination of the isolated constituents was accomplished through an integrated approach combining HR-ESI-MS, NMR spectra, and quantum mechanical simulations. Stereochemical assignments for compounds 1, 7, and 8 were unambiguously established through ECD spectral analysis. Subsequently, all isolated constituents underwent systematic screening to assess their inhibitory potential against cholinesterase. Among them, compounds 1 and 5 showed significant inhibitory activities on BChE with IC50 values of 8.54 μM and 23.77 μM, respectively, while compound 2 showed considerable inhibitory activity on AChE with IC50 values of 25.27 μM.