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

A new aporphine alkaloid, (<i>R</i>)-1,2-methylenedioxy-8-methoxy-9-hydroxynoraporphine (<b>1</b>), two new flavonoids, (<i>S</i>)-6,8-dihydroxy-7-methoxyflavanone (<b>7</b>) and (<i>S</i>)-6,8-dihydroxy-5,7-dimethoxyflavanone (<b>8</b>), along with seven known compounds, were isolated from the roots of <i>Fissistigma retusum</i> (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 <b>1</b>, <b>7</b>, and <b>8</b> were unambiguously established through ECD spectral analysis. Subsequently, all isolated constituents underwent systematic screening to assess their inhibitory potential against cholinesterase. Among them, compounds <b>1</b> and <b>5</b> showed significant inhibitory activities on BChE with IC₅₀ values of 8.54 μM and 23.77 μM, respectively, while compound <b>2</b> showed considerable inhibitory activity on AChE with IC₅₀ values of 25.27 μM.