The metabolism of the phenolic 1-benzyltetrahydroisoquinoline alkaloids was studied in cell cultures of Macleaya and Corydalis species. The crude alkaloid fraction obtained from feeding experiments was investigated by application of the combined LC/NMR and LC/APCI-MS (/MS) techniques. Several metabolites were detected, and their structures (6 and 8-14) were identified. Bioconversion of the phenolic 1-benzyltetrahydroisoquinoline (2) into the pseudoprotoberberine (8) was demonstrated for the first time. LC/APCI-MS and LC/CD experiments carried out on a chiral column permitted the deduction of the major enantiomeric form of the chiral metabolites. Thus, the combination of NMR, MS, and CD data permitted the structural elucidation and stereochemical analysis of the metabolites in the extract matrix solution, without isolation and sample purification prior to the coupling experiments.

(+/-)-1-Benzyl- N-methyltetrahydroisoquinolines 7-10 and 11-14 with one and two hydroxy groups on the aromatic rings, respectively, were fed individually to cultured cells of Corydalis and Macleaya species, respectively. The structures of the metabolites were determined by using combinatorial techniques, including LC/NMR, LC/MS-MS, and LC/CD. The enantiomeric excesses of the metabolites were derived from LC/CD and LC/MS-MS analyses. In cell cultures of Corydalis and Macleaya species, laudanine (7), with a hydroxy group at C-3', can form the berberine bridge at C-2' and C-6' to produce S- and R-enantiomers of 2,3,9,10- and 2,3,10,11-oxygenated protoberberines (20 and 21), respectively, whereas reticuline (11) and protosinomenine (12), incoporating a hydroxy group at C-3', form the berberine bridge at C-2' to furnish the S-enantiomer of 2,3,9,10-oxygenated protoberberines (23 and 21), respectively.

No abstract