Fractionation of the lipid extract of the marine cyanobacterium Lyngbya majuscula collected from Curacao afforded two quinoline alkaloids in low yield. Their structures were determined as 4,8-dimethyl-6-O-(2',4'-di-O-methyl-beta-D-xylopyranosyl)-hydroxyquinoline and 4,8-dimethyl-6-hydroxyquinoline on the basis of spectroscopic analysis, mainly 2D NMR spectroscopy. (C) 1997 Elsevier Science Ltd. All rights reserved.