Malonganenones A–C, novel tetraprenylated alkaloids from the Mozambique gorgonian Leptogorgia gilchristi

Three novel tetraprenylated alkaloids, malonganenones A–C (), were isolated from the gorgonian Leptogorgia gilchristi collected near Ponto Malongane, Mozambique. Compound is the first 3,7-disubstituted hypoxanthine to be discovered from a marine source, while and represent the first formamides to be isolated from gorgonians. The unexpected facile exchange of the formamide proton of with a deuteron originating from the NMR solvent used for spectroscopic analysis hampered initial attempts at the structural elucidation of this compound. The anti-oesophageal cancer activities of are compared with that of rietone (), a related triprenylated compound previously isolated from a South African soft coral.