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

Two new natural products were isolated from the marine cyanobacterium Rivularia sp. collected in Japan. Hennaminal possesses a very rare functional group, beta,beta-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.