2,4,5-Tribromo-1H-Imidazole in the Egg Masses of three Muricid Molluscs

Abstract

From analysis by gas chromatography/mass spectrometry (GC/MS), the presence of either 2,4,5-tribromo-1H-imidazole (1) or 3,4,5-tribromo-1H-pyrazole (2) was tentatively identified in lipophilic extracts from the egg masses of three muricid molluscs. Synthesis of these compounds, followed by comparison of the GC retention times and fragmentation patterns from electron impact MS, with those of the natural products, indicated that it was 2,4,5-tribromo-1H-imidazole rather than the pyrazole. This imidazole is likely to be responsible for some of the antimicrobial activity observed in the egg extracts. This is the first report of this compound from a natural source.

Keywords:

• Molluscan metabolite
• Tribromoimidazole
• Egg mass
• Antibacterial

Acknowledgements

We are grateful to Dr Manual Ballesteros (University of Barcelona) and Dr Carlos Gallardo (Universidad Astral de Chile) for assistance in the collection and identification of the egg masses from the Mediterranean and South American molluscs respectively. Dr Hernán Palma (Universidad Astral de Chile) kindly permitted the use of his laboratory for preparation of the Chilean extracts. We thank the University of Wollongong for financial support for this project.