Kabirimine, a New Cyclic Imine from an Okinawan Dinoflagellate

Mar Drugs. 2019 Jun 13;17(6):353. doi: 10.3390/md17060353.


On our quest for new bioactive molecules from marine sources, two cyclic imines (1, 2) were isolated from a dinoflagellate extract, inhibiting the growth of the respiratory syncytial virus (RSV). Compound 1 was identified as a known molecule portimine, while 2 was elucidated to be a new cyclic imine, named kabirimine. The absolute stereochemistry of 1 was determined by crystallographic work and chiral derivatization, whereas the structure of 2 was elucidated by means of spectroscopic analysis and computational study on all the possible isomers. Compound 1 showed potent cytotoxicity (CC50 < 0.097 µM) against HEp2 cells, while 2 exhibited moderate antiviral activity against RSV with IC50 = 4.20 µM (95% CI 3.31-5.33).

Keywords: cyclic imine; dinoflagellate; kabirimine; portimine; respiratory syncytial virus (RSV).

MeSH terms

  • Antiviral Agents / chemistry
  • Antiviral Agents / pharmacology
  • Aquatic Organisms / chemistry
  • Cell Line, Tumor
  • Dinoflagellida / chemistry*
  • Humans
  • Imines / chemistry*
  • Imines / pharmacology
  • Respiratory Syncytial Viruses / drug effects


  • Antiviral Agents
  • Imines