Characterization of isoquinoline alkaloids from Neolitsea sericea var. aurata by HPLC-SPE-NMR

Application of the HPLC-SPE-NMR technique to identify the alkaloids in an EtOH extract of the leaves of Neolitsea sericea var. aurata led to the characterization of 14 alkaloids while consuming plant material equivalent to 1.1 g. Of these, seven are N-oxides, four of which are new, namely, 9S,17S-pallidine N-alpha-oxide (6), 1S,2S-reticuline N-alpha-oxide (8), 6R,6aS-boldine N-beta-oxide (9), and 6S,6aS-N-methyllaurotetanine N-alpha-oxide (13). Their structures were also confirmed by partial synthesis.