Both enantiomers of keramaphidin B (1) were separated by using chiral HPLC, of which one may be a plausiblebiogeneticprecursor of ircinals A (4) and B (5) and manzamines A (2) and B (3), while the other may be associated with antipodes of manzaminealkaloids such as ircinols A (6) and B (7). Isolation and structure elucidation of a new manzamine congener, manzamine L (8), and absolute configurations