Isolation of Hennaminal and Isolation and Total Synthesis of Hennamide, Pyrrolinone Compounds from the Marine Cyanobacterium <i>Rivularia</i> sp.

Two new natural products were isolated from the marine cyanobacterium Rivularia sp. collected in Japan. Hennaminal possesses a very rare functional group, β,β-diamino unsaturated ketone, which has only been found in bohemamine-type natural products so far. Hennamide possesses a reactive N-acyl pyrrolinone moiety, which induces self-dimerization. The isolation and structure determination supported by computational chemistry and total synthesis, as well as the antitrypanosomal activities of hennaminal and hennamide are described.