Alkaloide der Pereiro‐Rinde, VI. Die Konstitution von Pereirin

Leucoridines A−D, Cytotoxic Strychnos−Strychnos Bisindole Alkaloids from Leuconotis

“…Leucoridine D ( 4 The NMR shifts showed that one unit of the bisindole corresponds to the same tubifoline-like unit as in the previous three alkaloids, except that in compound 4 C-16 was a methine and not a quaternary center as in the previous three alkaloids. In addition, examination of the NMR data of the other monomeric unit yielded a structure that corresponded to the strychnan compound anhydropereirine (or anhydrogeissoschizoline) (6), 35 previously obtained as a dehydration product of pereirine (or geissoschizoline). 35,36 All four aromatic shifts of the tubifoline-like unit were seen, while only three contiguous aromatic hydrogens of the anhydropereirine-like unit were present.…”

Indole and β-Carboline Alkaloids from Geissospermum sericeum

“…Geissoschizoline has been reported previously as a constituent of G. vellosii , but is also known as an acid hydrolysis product (2 M HCl) of the bisindole alkaloid geissospermine, a constituent of the bark of several species of Geissospermum . LC-MS analysis of the MeOH−H 2 O (9:1) extract of G. sericeum bark was carried out to determine whether geissoschizoline was produced only as an artifact of the isolation procedure used here, as this incorporated a standard acid workup step with 0.5 M HCl (Experimental Section).…”