Nakinadines B-F: new pyridine alkaloids with a β-amino acid moiety from sponge Amphimedon sp.

Five new 3-alkylpyridine alkaloids with a β-amino acid moiety, nakinadines B-F (1-5), have been isolated from an Okinawan marine sponge Amphimedon sp. (SS-1059), and the structures and stereochemistry were elucidated by spectroscopic data. Nakinadines B (1) and C (2) showed modest cytotoxicity.