Comprehensive study of alkaloids from Crinum asiaticum var. sinicum assisted by HPLC-DAD-SPE-NMR.

A comprehensive study of the alkaloids presentin the leaves of Crinum asiaticum var. sinicum, assisted by HPLC-SPE-NMR, led to the characterization of 21 compounds of similar polarity on an analytical scale. Thirteen of these were isolated for further structural confirmation. Seven are proved to be new, namely, (+)-siculine (4), 1-epijosephinine (11), 7-methoxycrinamabine (10), 2-O-acetylcrinamabine (16), 3-O-acetyl-8-O-demethylmaritidine (17), 2-O-acetylbulbisine (18), and 1-O-acetylbulbisine (19). In addition, dihydrovittatine (6) and 8-O-demethyloxomaritidine (21) were isolated for the first time from Nature, although they have been prepared previously as synthetic products. Their structures were established by spectroscopic analysis.