Amide-Iminoate Isomerism in Antineuroinflammatory Isoquinoline Alkaloids from .

Six new (-) and two known (, ) alkaloids that were chemically inseparable geometrical isomers (two isomers present in a 1:1 ratio for - and and a 1:3 ratio for , , and ) were identified from . Their structures and absolute configurations were determined by spectroscopic data analyses and comparison of their experimental and calculated ECD spectra. Moreover, using NOE correlations and DFT-based calculations, the NMR data of each geometrical isomer of - were assigned.