title: Characterization of bioactive glycolipids from Scytonema julianum (cyanobacteria).
abstract: Cyanobacteria serve as a rich source of novel bioactive metabolites. Few studies on glycolipids reported them as having specific biological activities. In this study, total lipids of Scytonema julianum, a filamentous cyanobacterium isolated from a Greek cave, were separated into neutral and phospho- and glycolipids, and the latter were further fractionated by high-performance liquid chromatography (HPLC). Each glycolipid fraction was tested in vitro for its ability to inhibit platelet-activating factor (PAF)- and thrombin-induced washed rabbit platelet aggregation and/or to cause platelet aggregation. The structures of the most active fractions were elucidated by biological assays, by chemical determinations and identified by electrospray mass spectrometry. One fraction was a potent inhibitor of PAF-induced platelet aggregation. Structural studies of this fraction indicated the existence of a phosphoglyco-analog of acyl-sphingosine. Two fractions causing platelet aggregation were detected and identified as phosphoglycolipids. The first one was identified as a phosphoglyco-analog of acyl-acetylated sphingosine and the second one as a glyco-analog of phosphatidylglycerol. The presence of the above bioactive compounds demonstrates new types of lipids in cyanobacteria in regard to the structure and biological activity. In addition, the identified bioactive lipids may contribute to the allergic character of cyanobacteria.
authors.affiliation: Department of Science of Dietetics-Nutrition, Harokopio University, 70 El. Venizelou Str., 176 71 Athens, Greece. antonop@hua.gr
authors.forename: Smaragdi
authors.initials: S
authors.lastname: Antonopoulou
authors.forename: Tzortzis
authors.initials: T
authors.lastname: Nomikos
authors.forename: Alexandra
authors.initials: A
authors.lastname: Oikonomou
authors.forename: Adamantini
authors.initials: A
authors.lastname: Kyriacou
authors.forename: Michalis
authors.initials: M
authors.lastname: Andriotis
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Fragopoulou
authors.forename: Adriani
authors.initials: A
authors.lastname: Pantazidou
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase / Q000378:metabolism; D000107:Acetylation; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry*; D006017:Glycolipids / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013058:Mass Spectrometry; D015394:Molecular Structure
chemical_list: D006017:Glycolipids; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase