Bartolosides E-K from a Marine Coccoid Cyanobacterium

J Nat Prod. 2016 Oct 28;79(10):2504-2513. doi: 10.1021/acs.jnatprod.6b00351. Epub 2016 Sep 28.

Abstract

The glycosylated and halogenated dialkylresorcinol (DAR) compounds bartolosides A-D (1-4) were recently discovered from marine cyanobacteria and represent a novel family of glycolipids, encoded by the brt biosynthetic gene cluster. Here, we report the isolation and NMR- and MS-based structure elucidation of monoglycosylated bartolosides E-K (5-11), obtained from Synechocystis salina LEGE 06099, a strain closely related to the cyanobacterium that produces the diglycosylated 2-4. In addition, a genome region containing orthologues of brt genes was identified in this cyanobacterium. Interestingly, the major bartoloside in S. salina LEGE 06099 was 1 (above 0.5% dry wt), originally isolated from the phylogenetically distant filamentous cyanobacterium Nodosilinea sp. LEGE 06102. Compounds 5-11 are analogues of 1, with different alkyl chain lengths or halogenation patterns. Their structures and the organization of the brt genes suggest that the DAR-forming ketosynthase BrtD can generate structural diversity by accepting fatty acyl-derived substrates of varying length. Compound 9 features a rare midchain gem-dichloro moiety, indicating that the putative halogenase BrtJ is able to act twice on the same midchain carbon.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / isolation & purification*
  • Antineoplastic Agents / pharmacology
  • Cyanobacteria / chemistry*
  • Cyanobacteria / genetics
  • Drug Screening Assays, Antitumor
  • Glycolipids / chemistry
  • Glycolipids / isolation & purification*
  • Glycolipids / pharmacology
  • Glycosides / chemistry
  • Glycosides / isolation & purification*
  • Glycosides / pharmacology
  • Humans
  • Marine Biology
  • Molecular Structure
  • Multigene Family
  • Nuclear Magnetic Resonance, Biomolecular
  • Resorcinols / chemistry
  • Resorcinols / isolation & purification*

Substances

  • Antineoplastic Agents
  • Glycolipids
  • Glycosides
  • Resorcinols