Erythrina alkaloids. Part 6. Isolation and characterisation of alkaloids from Erythrina berteroana seeds and leaves: formation of oxoerythroidines

Abstract

The major alkaloids present in E. berteroana seeds and leaves are α- and β-erythroidines (1) and (3). Smaller amounts of erysodine (5a), erysovine (5b), erysopine (5c), erysoline (5d), and erysonine (5e) were also detected. Preparative h.p.l.c. studies also revealed the presence of new alkaloids 8-oxo-α-erythroidine (2) in the extract of the seeds, and of 8-oxo-β-erythroidine (4) in the extract of the leaves. Both compounds could also be obtained by direct oxidation of the corresponding erythroidines. These new 8-oxo-erythroidines were fully characterised by a combination of spectroscopic methods, and by comparisons with the spectra of the parent erythroidines.