Niphatesines E–H, new pyridine alkaloids from the Okinawan marine sponge Niphates sp.

Four new mono-3-alkyl-substituted pyridine alkaloids, niphatesines E–H (1–4), possessing oxime methyl ether or methoxyamine functionality have been isolated from the Okinawan marine sponge Niphates sp. and the structures elucidated by spectral and chemical means. These pyridine alkaloids exhibited cytotoxic and antimicrobial activities.