Nangallenes A and B, halogenated nonterpenoid C₁₅-acetogenins from the Bornean red alga Laurencia nangii

Abstract

Two new halogenated nonterpenoids C₁₅-acetogenins, nangallenes A-B (1–2), together with two known halogenated compounds itomanallene A (3) and 2,10-dibromo-3-chloro-α-chamigrene (4), were isolated and identified from the organic extract of the marine red alga Laurencia nangii Masuda collected from the coastal waters in Semporna, Borneo. Their structures were established by means of spectroscopic analysis including IR, high-resolution electrospray ionization mass spectrometry (HRESI-MS), and 1D and 2D NMR techniques. All these metabolites were submitted for the antifungal assay against four species of selected marine fungi. Compounds 1–4 showed potent activity against Haliphthoros sabahensis and Lagenidium thermophilum.

Keywords:

• Laurencia nangii
• Rhodomelaceae
• red alga
• C₁₅-acetogenin
• halogenated compound
• Borneo

Acknowledgements

The authors would like to thank Prof. Dr. Kishio Hatai (Universiti Malaysia Sabah) for providing the fungal strains and Prof. Dr. Tatsufumi Okino along with Mr. Takafumi Ishikawa (Hokkaido University) for their kind assistance during data comparison.