Maculalactone L and three halogenated carbazole alkaloids from Kyrtuthrix maculans

Maculalactone L, a novel tribenzylbutyrolactone secondary metabolite has been obtained from one colony of the epilithic encrusting cyanobacterium Kyrtuthrix maculans, during the course of a wide-ranging survey of Kyrtuthrix on Hong Kong shores. Maculalactone L may be derived from maculalactone A, described previously from this species, by oxidation reactions. Three halogenated carbazole alkaloids are also described.