11-oxoaerothionin: a cytotoxic antitumor bromotyrosine-derived alkaloid from the Caribbean marine sponge Aplysina lacunosa.

A new cytotoxic bromotyrosine-derived secondary metabolite, 11-oxoaerothionin [3], was isolated from the Caribbean sea sponge Aplysina lacunosa. The structure of 3 was argued on the basis of detailed spectroscopic analysis and by chemical conversion to the known antibiotic compound 11-hydroxyaerothionin [2]. When screened against a panel of four human cell lines, 11-oxoaerothionin [3] showed pronounced as well as selective antitumor activity toward the human colon (HCT 116) cell line within the limited concentration range of 0.01-0.1 microgram/ml.