Pyrroloquinoline derivatives from a Tongan specimen of the marine sponge Strongylodesma tongaensis. Issue 28 (11th July 2019) - Taufa, Taitusi
Graphical abstract: Highlights: New pyrroloquinolines came from the cryptic sponge S. tongaensis. Makaluvamine W is only the 2nd oxazole-containing pyrroloquinoline. Full NMR analysis and biosynthetic reasoning was used to establish makaluvamine W. Abstract: Pyrroloquinoline alkaloids are well known bioactive metabolites commonly found from latrunculiid sponges. Two new pyrroloquinoline alkaloids, 6-bromodamirone B (1 ) and makaluvamine W (2 ), were isolated from the Tongan sponge Strongylodesma tongaensis. Makaluvamine W (2 ) contains an oxazole moiety, which is rare in this large group of natural products, and is the first example of a pyrroloquinoline with nitrogen substitution at C-8. Both1 and2 lacked activity against a human promyelocytic leukemia cell line (HL-60), supporting the premise that an intact iminoquinone moiety plays a key role in the cytotoxicity of this compound class. The chemotaxonomic impact of these makaluvamine-type compounds is also discussed.