Hectochlorin (1) was isolated from marine isolates of Lyngbya majuscula collected from Hector Bay, Jamaica, and Boca del Drago Beach, Bocas del Toro, Panama. The planar structure was deduced by one- and two-dimensional NMR spectroscopy. X-ray crystallography was used to determine the absolute stereochemistry of hectochlorin as 2S,3S,14S,22S. Hectochlorin is equipotent to jasplakinolide (5) in its ability to promote actin polymerization, but unlike jasplakinolide, is unable to displace a fluorescent phalloidin analogue from polymerized actin. In addition, hectochlorin shows both a unique profile of cytotoxicity by the COMPARE algorithm and potent inhibitory activity toward the fungus Candida albicans. Structurally, hectochlorin resembles dolabellin and the recently reported lyngbyabellin class of compounds.

No abstract

Four new metabolites have been isolated from a marine red cyanobacterium, Lyngbya majuscula, collected at Boca del Drago Beach, Bocas del Toro, Panama. The planar structures were elucidated by 1D and 2D NMR techniques. These compounds were assigned the trivial names pseudodysidenin (2), dysidenamide (3), nordysidenin (4), and dragonamide (7).

3-Hydroxy-N-methylwelwitindolinone C isonitrile (3), 3-hydroxy-N-methylwelwitindolinone C isothiocyanate (4), and the novel cyclic ether N-methylwelwitindolinone D isonitrile (6) are three new alkaloids from two terrestrial Fischerella spp. belonging to the Stigonemataceae. Photooxidation of N-methylwelwitindolinone C isonitrile (1) leads to isonitriles 3 and 6. Isonitrile 3 is readily hydrated to 3-hydroxy-N-methylwelwitindolinone C formamide (5), an artifact produced during the isolation procedure.